GRAPE GROWING is an important part of California's agricultural industry— the
state produces about 80 per cent of all grapes grown in the country.

This circular gives rather complete instructions for the commercial production
of grapes and includes some very late information that should help growers to im-
prove both the quality and yield of vineyards.

Success depends largely on a wise choice of land and selection of a variety or
varieties that will adapt themselves to the area, followed by good cultural practices,
as given in this circular. This principle applies to all types of grapes— table, wine,
raisin, juice, or canning.

Considerable investment is needed to get into the grape producing business
and it takes a minimum of 4 years from the time of starting before any income is
derived from the crop.

The marketing possibilities of additional grapes (at the time this circular was
revised) do not appear to be favorable. With the possible exception of a few choice
wine varieties, the supply of California grapes currently exceeds the demand.

The Authors:

This circular was written by H. E. Jacob (deceased), Associate Professor of
Viticulture and Associate Viticulturist in the Experiment Station, Davis. This
revision was prepared by A. J. Winkler, Professor of Viticulture and Viticul-
turist in the Experiment Station, Davis.

Acknowledgment

is made of the assistance of W. B. Hewitt, Associate Professor of Plant Pathol-
ogy, and of L.M.Smith, Professor of Entomology, and E.M.Stafford, Assistant
Professor of Entomology, in the preparation of the sections on plant diseases
and pests, respectively.

ere is some background information
on the grapes being grown in California

High prices from 1942 to 1946 stimu-
lated an interest in new grape plantings
unequaled since the planting spree of
the early 1920's. Ruinously low prices
followed that former expansion. Unwar-
ranted expansion of the vineyard acreage
since 1946 has increased the overall sup-
ply of grapes over and above present
demands. The world acreage of raisin-
variety grapes is the highest in history,
and there seems to be no good reason
to expect that the market for California
raisins in the foreseeable future will ex-
ceed that of prewar years. New plantings
of raisin grapes should therefore be not
greater than is needed to replace over-age
vineyards that are uprooted. The over-all
production of table grapes also appears
to be more than adequate to supply the
demands.

Acreage shifts among varieties and lo-
calities may be expected, but are not pre-
dictable; certainly no over-all expansion
appears to be in order. Common wine-
variety-grape production appears ade-
quate to supply the probable demand for
standard wines. Good wine varieties
should continue in demand beyond pres-
ent supply. These include such varieties
as Cabernet Sauvignon, Gamay Beau-
jolais, Semillon, Sauvignon blanc, Pinot
blanc, Sylvaner, and White Riesling for
the coastal valleys; and Palomino, Gren-
ache, and Mission for the interior valleys.

Most California grapes
are of European origin

The cultivated grapes of California are
mostly of the kind grown in the coun-
tries bordering the Mediterranean and
referred to as "European" grapes. They
are derived from one wild species— Vitis
vinifera— native to western Asia. Of the

cultivated vines in the world more than
90 per cent are pure vinifera. Most of the
varieties cultivated in the remainder of
the United States, east of the Rocky
Mountains, have been derived from
American wild vines or from crosses be-
tween them and V. vinifera. These are
properly called "American" grapes.

California has a half-million acres of
vineyards, constituting about 80 per cent
of the total grape acreage of the United
States, but only 3 per cent of the total
world acreage. The state produces about
2 per cent of the world's wine, 15 per
cent of the world's table grapes, and 40
per cent of the world's raisins.

There are five main
classes of grapes

Grapes are conveniently grouped into
five general classes according to the pur-
poses for which they are used: (1) wine
grapes, (2) table grapes, (3) raisin
grapes, (4) sweet (unfermented) juice
grapes, and (5) canning grapes. Any
variety can be fermented into a kind of
wine, can be eaten fresh, dried into
raisins, or made into sweet grape juice;
but each variety is usually better suited
to one purpose than to the others.

Wine grapes may be defined as those
varieties known to be capable of produc-
ing satisfactory wine in some locality.
Table or dry wines require grapes of high
acidity and moderate sugar content, while
dessert or sweet wines require grapes hav-
ing high sugar content and moderately
low acidity.

In addition, quality wines which are
outstanding in bouquet, flavor and gen-
eral balance, require grapes with special
characteristics such as those of Riesling,
Semillon, Cabernet, Pinot noir and simi-

[3]

lar varieties, when they are grown under
favorable conditions.

The best table wine grapes are pro-
duced in the cooler districts and the best
dessert wine grapes in the warmer dis-
tricts. Although the texture of the skin
and the pulp does not affect the quality
of the wine, thick skin and firm pulp may
reduce the juice yield, and thin skin and
very soft pulp may increase the care re-
quired in harvesting and transporting
the fresh grapes. Most good wine grapes
are of small or medium size. The best are
usually light or moderate bearers.

Table grapes. Grapes to be used
fresh, either for food or for decoration,
are commonly called table grapes. They
must be attractive in appearance; must
possess good eating, carrying, and keep-
ing qualities; and— to be widely used-
must be produced and sold at a relatively
low cost.

The tastes of the consumer vary in dif-
ferent markets. Large size, brilliant color,
and unusual form are generally appre-
ciated. In American markets, seedlessness
is an advantage. Where table grapes must
be shipped long distances or stored for
considerable periods, firmness of pulp,
toughness of skin, and adherence to the
stems are important. Except for the
Thompson Seedless (Sultanina), which
owes its popularity primarily to its seed-
less character, all the important table
varieties grown in California— Flame
Tokay, Emperor, Malaga, Red Malaga
(Molinera), and Ribier (Alphonse La-
vallee)— have attained their prominence
because they possess a better combina-
tion of attractive appearance, good eating
quality, resistance to injury in handling,
and good keeping in storage than any
other varieties sufficiently tested under
the general cultural and marketing con-
ditions of the state.

The particular combination of charac-

teristics that will render a table grape
attractive and successful depends not
only upon the variety but also upon the
soil and the climate. For this reason, cer-
tain varieties can be grown profitably
only in limited areas. Thus the Flame
Tokay does best near Lodi; the Emperor
on the east side of the San Joaquin Valley
in Tulare and Fresno counties.

To attain the quality of fruit and the
quantity of crop necessary for success,
table grapes in general require a warm
climate and a favorable, but not neces-
sarily highly fertile, soil. Very early vari-
eties are most profitable in the warmest
and earliest localities. In the later locali-
ties the midseason and late varieties, more
attractive in appearance and better in
shipping and keeping quality, are pre-
ferred.

Raisin grapes. Raisins are essentially
dried grapes; yet different varieties and
different methods of drying may yield
very unlike products, so much so that in
other countries a distinction is often made
between raisins and "dried grapes." De-
sirable characters in a variety to be used
for raisins include: (1) soft texture of
the dried product; (2) lack of tendency
of the raisins to stick together when
stored; (3) seedlessness; (4) earliness
of ripening; (5) marked, pleasing flavor
of the raisins; (6) ease of drying; (7)
large or very small size; and (8) high
productivity of the vines. Of the thou-
sands of grape varieties known, only
three— Thompson Seedless, Muscat of
Alexandria, and Black Corinth (Zante
Currant)— are used to make most of the
world's raisins. The Thompson Seedless
and Muscat of Alexandria are widely
grown in the San Joaquin Valley of Cali-
fornia, whereas the Black Corinth is
grown principally in Greece and Aus-
tralia and is of only minor importance
in this state.

Unfermented-juice grapes. For the

making of sweet, unfermented grape
juice it is necessary, or at least desir-
able, for the grapes to retain their nat-
ural fresh-fruit flavor throughout the
processing required to clarify and pre-
serve the juice. In America the juice is
most commonly pasteurized after it has
been clarified. Most vinifera varieties
when pasteurized by the usual method
lose their fresh flavor and acquire an
unpleasant cooked taste. Even the strong
Muscat flavor changes from that of the
fresh grape to one suggestive of Muscat
raisins. The strong, "foxy" flavor of cer-
tain American varieties, particularly the

Concord, comes through the usual proc-
essing and pasteurization almost un-
changed; hence most of the grape juice
made in America is of Concord grapes
alone or of Concord blended with other
varieties. In parts of Europe, where the
juice is sterilized by close filtration only,
then bottled under sterile conditions, vini-
fera varieties are commonly used.

California has never been an important
producer of unfermented grape juice.

Canning grapes are those used pri-
marily in combination with other fruits
in the production of canned fruit salad
and fruit cocktail. Only seedless sorts are
used, usually the Thompson Seedless.

ertain basic needs must be considered be-
fore going into commercial grape growing

Most vinifera grapes need long, warm-
to-hot, dry summers and cool winters for
their best development. They are not
adapted to humid summers, whether tem-
perate or tropical, because of their sus-
ceptibility to certain fungus diseases that
flourish under such conditions. Neither
will they withstand intense winter cold
(below 0° F) without protection. Frosts
occurring after vine growth starts in the
spring may kill most of the fruitful shoots
and disastrously reduce the crop.

To mature the fruit, a long growing
season is needed. Rain during the win-
ter is desirable, though deficiencies can
be made up by irrigation. Rains early in
the growing season make disease control
difficult but are otherwise not detrimental
to growth. Rains or cold, cloudy weather
during the blooming period, however,
may cause poor setting of the berries.
Rains during the ripening and harvesting
periods result in much damage through
rotting of the fruit. In relatively cool re-
gions a higher humidity can be tolerated

than in warmer regions. Where raisins
are to be made by natural sun-drying, a
month of clear, warm, rainless weather
after the grapes are ripe is essential.

American grapes— Concord and others
—withstand humid summers and cold
winters better than pure vinifera varie-
ties. They do better in regions of moderate
summer humidity than in the very dry,
semiarid climate of the interior valleys
of California. Rare, indeed, are the
grapes that will endure high humidity
coupled with high temperatures, a condi-
tion common in the tropics.

Some grapes need
more heat than others

Vinifera grapes start growth in the
spring soon after the daily mean tempera-
ture reaches 50° F. A winter rest period
of 2 or 3 months, during which the aver-
age daily mean temperature is below 50°,
with some freezing but with no tempera-
tures below 0°, is desirable. Daily mean
temperatures of at least 65° are necessary

for proper development and ripening of
most varieties ; and somewhat higher tem-
peratures, 70° to 85°, are needed for
some. The time elapsing from blooming
to ripening is largely determined for each
variety by the effective-heat summation
for a given place, this is usually calcu-
lated by subtracting 50° from the mean
temperature for each day and adding to-
gether, algebraically, the quantities thus
obtained. The result is expressed as de-
gree-days. Where whole months are in-
volved, the same result is obtained by
multiplying the monthly mean tempera-
ture, less 50° F, by the number of days
in the month.

Table 1 on this page shows how effec-
tive-heat summation can be figured for
a given place and time. In this table,
Fresno was used as a location and the
average mean temperature figures were
taken from Summary of the Climatologi-
cal Data for the United States, by Sec-
tions, published by the Weather Bureau
of the U. S. Department of Agriculture,
Washington, D.C. Copies of this booklet
will be sent free upon request to Wash-
ington.

The earliest varieties require about

1,600 degree days; the latest at least 3,500
degree days. Beginning the summation
of heat at the time of full bloom, Thomp-
son Seedless will be ripe for table use
(18° Balling) when the temperature sum-
mation above 50° reaches 2,000 degree-
days. This variety will be fully ripe for
raisins (25° Balling) when the summa-
tion reaches 3,000. Similarly, Tokay will
be ripe for table use at about 2,250 and
Emperor at about 3,300 degree-days.

Temperature, especially during the
ripening period, also strikingly affects
the sugar and/or acid content of the
grapes— hence their value for various
uses. On the basis of temperature, or
more specifically the summation of heat
as degree-days above 50° F for the ar-
bitrary period April 1 to October 31, any
grape-producing area of California falls
into one or another of five convenient
temperature groups or regions. These
groups, with representative locations, are
as follows :

1. Cool regions (less than 2,500 degree-
days of heat from April 1 to October 31) ,
as at Napa, Oakville, Hollister, Mission
San Jose, Saratoga, Bonny Doon, Guerne-
ville, Santa Rosa, and Sonoma.

Table 1
EFFECTIVE-HEAT SUMMATION

l
Month

April

May

June

July

August .

September

October

2
No. days

30
31
30
31
31
30
31

Average
mean temp.

61°
67°
75°
82°
80°
74°
65°

Col. 3 — 50°

11°
17°
25°
32°
30°
24°
15 c

Degree

days

330
527
750
992
930
720
465

Total heat
to date

330

857
1,607
2,599
3,529

4,249
4,714

Col. 5 is arrived at by multiplying the figure in col. 2 by that in col. 4.
Col. 6 is arrived at by addition of the figures in col. 5.

When the average mean temperature falls below 50° F, the figures in columns 4 and 5 will be "minus'
figures and should be subtracted from the total in column 6.

2. Moderately cool regions (2,501 to
3,000 degree-days of heat from April 1
to October 31), as at Rutherford, St.
Helena, Glen Ellen, Healdsburg, San
Jose, Los Gatos, Soledad, and Santa Bar-
bara.

3. Warm regions (3,001 to 3,500 de-
gree-days of heat from April 1 to October
31), as at Calistoga, Ukiah, Hopland,
Cloverdale, Livermore, Paso Robles, and
Alpine (in San Diego County).

4. Moderately hot regions (3,501 to
4,000 degree-days of heat from April 1
to October 31), as at Davis, Sacramento,
Lodi, Manteca, Modesto, Ojai, Ontario,
and Escondido.

5. Hot regions (more than 4,000 de-
gree-days of heat from April 1 to October
31), as at Livingston, Merced, Madera,
Fresno, Visalia, Delano, Bakersfield,
Chico, Red Bluff, Redding, and San Ber-
nardino.

The cool and moderately cool regions
(1 and 2) produce the best table wines;
the warm regions (3) the best natural
sweet wines; and the moderately hot and
hot regions (4 and 5) the best dessert

wines, together with the commercial table
and raisin grapes.

A wide range of
soils is used

Grapes grow fairly well in many soils.
While in nearly every grape-growing re-
gion preferences will be expressed for
certain types of soil, the fact remains that
throughout the world grapes are grown
commercially in practically every type of
soil, from gravelly sands to clay loams;
from shallow to very deep soils; from
high to low fertility.

It is well, however, to avoid very heavy
clays, very shallow soils, poorly drained
soils, and soils containing relatively high
concentrations of salts of alkali metals,
or boron or other toxic materials.

The deeper and more fertile soils usu-
ally produce the heaviest crops and are
usually preferred for raisins, common
wine grapes and such table grapes as
Tokay and Thompson Seedless. Certain
varieties, notably Malaga and Emperor,
attain higher quality when grown on
soils of limited depth.

etting the proper start is essential to
the commercial success of a vineyard

A favorable combination of locality,
variety, cultural methods and proper
utilization of the crop is essential to suc-
cessful grape growing. Before deciding
to plant grapes on an existing plot, or
to purchase a plot with the idea of plant-
ing grapes, the prospective grower is
advised to consult his local County Farm
Advisor, and talk with successful growers
in the area— get all the information pos-
sible. Information is needed on such fac-
tors as climate, temperature, wind, frost,
rainfall, topography, depth of soil, fer-
tility, availability of water, roads and
distance to market, sources of labor.

As a rule it is usually safer to plant a
variety that has been proven successful
in the area, but that tends to increase
competition. Planting a new variety in
an old area, or any variety in a new grape
growing area is highly hazardous and
should be done only on a trial basis.

Clear the land and
prepare it carefully

Before planting, clear the land of trees,
stumps, large stones, noxious weeds, and
rodent pests. If irrigation is possible, the
land should be leveled or graded prop-
erly. It should then be well plowed 8 or

[7]

10 inches deep; and if a plow sole or
other hard substratum that can be eco-
nomically broken up is present, subsoil-
ing is advisable. The soil surface need
not be pulverized and compacted, as for
a seedbed, but should be freed from large
clods that might interfere with the use
of the planting line and with the actual
planting.

When the position of the rows has been
determined, it is desirable to subsoil the
row. The cost of this operation is more
than repaid in the saving of labor in
planting and staking.

Choose stock that
will suit your needs

One-year-old rootings of the desired
fruiting variety should generally be used
in planting a vineyard in any location,
except where the presence of phylloxera
or a heavy infestation of nematodes re-
quires the use of special resistant root-
stocks. Nearly the whole north coast re-
gion and parts of the Sacramento and
San Joaquin valleys and of the intermedi-
ate central valley region are infested with
phylloxera. Within such areas one should
plant only grafted vines, or rootings of
rootstocks resistant to phylloxera which

are later to be budded or grafted to the
desired fruiting variety. (See page 63).

Several factors affect
the spacing of the vines

Wide spacing of vines, particularly in
one direction, makes for ease and econ-
omy of operation. The cost of cultiva-
tion, for example, is determined more
by the number and length of rows than
by the actual acreage in the vineyard.
Harvesting labor and costs are materially
reduced if the grapes can be hauled out
from between the rows rather than be
carried out to the avenues. The cost of
brush disposal is nominal if the brush can
be disked or shredded, but becomes a
considerable item when the material must
be carried or hauled away. Power-dusting
equipment can be used only if the rows
are far enough apart to permit movement
of the machine through the vineyard. The
initial costs— of vines, planting, stakes,
and training— are directly proportional
to the number of vines, not to the acreage.
Table 2 shows the number of rows and
the vines per row in a square 10-acre
planting with the various common spac-
ings; the table also shows the number of
vines per acre.

Table 2

DISTANCE BETWEEN AVENUES, NUMBER OF ROWS, AND VINES PER ROW

IN A SQUARE 10-ACRE PLANTING WITH VARIOUS SPACINGS;

AND NUMBER OF VINES PER ACRE

Spacing

Approximate

distance between

avenues

Number of rows*

in a
square 10 acres

Vines per row

in a
square 10 acres

Number
of vines
per acre

feet
7X7

feet
200
200
200
300
300
300
620

89
78
70
63
63
63
53

87
78
87
102
86
76
78

774

8X8

608

7X9

609

6 X 10

643

7 X 10

542

8 X 10

479

8 X 12

413

Avenues about 20 feet wide are allowed for on each side of the 10-acre block.

[8]

Moderately close planting, on the other
hand, usually produces larger crops while
the vines are young. Unless the wide spac-
ing is carried to extremes, the crop after
the vines are mature is about the same.

The most desirable spacing, therefore,
is the widest that one can have without
reducing the crop in the mature vineyard.
In general, a closer planting is used for
small-growing varieties, cool regions, and
poor soils; wider spacing for large-grow-
ing varieties, warm regions, and fertile
soils. In the past, in California spacings
of 7 x 7 feet and 8x8 feet have been cus-
tomary in the cooler regions and 10 x 10
feet or 8 x 12 feet in the hotter ones.

Square planting— the rows and the
vines in the row the same distance apart—
permits cross-cultivation, an advantage
where small tools are used. Avenue ar-
rangement—the rows farther apart than
the vines in the row— permits the use of
large equipment in one direction. Special
tools, such as the Kirpy (French) plows,
eliminate the need to cross the vineyard
in cultivation. Economical tractor-pow-
ered cultivation, power dusting, and haul-
ing the grapes out of the tqws require
10 feet or wider spacing of the rows. Since
the advantages of the avenue arrange-
ment seem far to outweigh the disadvan-
tages, such a pattern is recommended for
all new vineyards.

Table 3 on page 10 gives recommended
planting distances and other data on some
of the more popular grape varieties
grown in California.

Lay out the vineyard
carefully

In large vineyards— 40 acres or more-
surveying instruments are convenient for
dividing the area accurately into blocks
of the desired size. The position of each
row may be located with the surveyor's
chain or with a special "row chain" made

by melting buttons of solder on a No. 11
smooth galvanized wire at the distance
the rows are to be spaced. A soldering
flux of hydrochloric acid and zinc chlo-
ride will help to make the solder stick
to the wire.

The individual vines in each row are
nearly always located by using a plant-
ing line, made as described for the row
chain except that the solder buttons are
spaced according to the spacing distance
of the vines in the row. The positions of
the vines are marked by driving tem-
porary planting pegs, 1 x 1 x 12 inches,
or permanent stakes at each button on
the planting line. Regularity in lining up
the vines and stakes and in planting the
vines is necessary for economical han-
dling of the vineyard later.

Directions for laying out a contour
planting are given in Extension Circular
152, Contour Planting of Unirrigated
Perennials which may be obtained from
your Farm Advisor, or by writing to
Publications Office, University of Cali-
fornia, College of Agriculture, 22 Gian-
nini Hall, Berkeley. Some of the factors
to be considered in contour planting of
grapes are discussed on page 35 of this
circular.

Keep the cuttings
moist while planting

The rootings, or grafted vines, are
pruned before the planting; the tops are
cut back to a single good spur of one or
two buds. For convenience in usual plant-
ing, the roots are shortened to 3 or 4
inches; for hydraulic planting they are
cut back to 1 inch (see below) . All roots
within 8 inches of the top of the pruned
vine are removed entirely.

The vines must be carefully protected
from drying out in all handling opera-
tions, from their removal from the nurs-
ery to their planting in the vineyard.

[9]

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When stored they should be heeled-in
(partially or completely buried) in moist
sand or soil in a cool place. While being
moved from the storage place to the vine-
yard they must be well covered with moist
sacks or canvas or, better still, hauled in
tubs containing 2 or 3 inches of water.
The planters carry the vines in planting
cans (often made from 5-gallon paint
buckets or 5-gallon oil cans). Two or 3
inches of water in the planting cans will
keep the roots wet.

The holes for the vines are all dug on
the same side of the planting pegs or
stakes. When the holes are made with hy-
draulic pressure, the hydraulic point is
forced into the soil beside the peg, to a
depth that will take the vine. In digging
the hole, one does not remove the peg, but
digs so that the side or corner of the hole
at the peg slopes away from the peg 1 or
2 inches distant at the bottom. The hole
should be slightly deeper than the vine is
long. Then the vine is dropped into the
hole with the top close to the peg; the
hole is partly filled— one half or two
thirds of its depth— with moist top soil;
the vine is raised to the proper height
and the soil solidly packed about the
roots with the feet; the hole is filled
almost completely and again the soil
is packed firmly; then the hole is com-
pletely filled and the top of the vine cov-
ered, leaving the soil over the top well
pulverized but loose. When the work is
completed, the top of the vine should be
exactly at the side of the peg, and the
roots 1 or 2 inches away from the peg.
All vines must slant in the same direction,
so that the permanent stakes may be
placed close to each vine on the side
toward which the top slants without
danger of breaking the vine. Rootings of
the fruiting varieties are planted so that
the two buds left after pruning are just
above the general level of the ground.

Bench-grafted vines are planted with the
union about an inch above ground level.
Rootstock rootings that are to be budded
or grafted in the field should have 4 or 5
inches of the main stem above ground
level, in order that the graft union may
be above the surface of the soil. The tops
of all are covered, to a depth of % to 2
inches, with a mound of loose soil to pre-
vent drying before growth starts.

Provide support for
the young vines

All vines should have some support,
temporary or permanent. For head-
pruned vines, stakes 4 to 6 feet long
are sufficient. In six to ten years these
may be removed, as the vines should then
be self-supporting. For simple two-wire
trellises, a 6-foot stake at each vine is suf-
ficient, with two no. 11 or no. 12 smooth,
galvanized fencing wires stretched along

the row at 34 and 46 inches from the
ground. The stakes are best put in place
before the vineyard is planted, but for
economy the wire may be left off until
the winter immediately after the planting ;
it should not be delayed longer.

Most grape stakes used in California
are split from coast redwood. The best
of them may last 20 years or more in the
vineyard, but those made from young
trees or sap wood may rot and break off
in as short a time as 3 years.

Since the stakes are costly and replace-
ments often involve considerable labor,
treating the stakes with a suitable wood
preservative is advised. Soak the stakes
for 24 hours in undiluted wood-preserva-
tive creosote, or in 5 per cent solution
of pentachlorphenol, in diesel oil. Either
of these treatments will be effective. Only
that portion of the stake that goes into
the ground need be treated.

The photo below shows a typical sloping, wide-top trellis. This type of support is recommended
for some of the large-growing table-grape varieties (see page 10).

3S#i£*Jfe&* i

[12]

Stakes treated with either of these pre-
servatives must not be placed close to
vines until the preservative has com-
pletely dried. This may be a month or
more after treating.

Often, for large-growing table-grape
varieties, a "wide-top" trellis is con-
structed by tying a crossarm (2x2 inches
x 3 feet) to the top of each stake or each
alternate stake and bracing the lower end
to hold the crossarm at an angle of about
30° from the horizontal. The lower end

is about 15 inches long; the upper end
about 21 inches. One wire is usually
fastened to the stakes just below the cross-
arms, and three wires are used on the
crossarms. This type of trellis has certain
advantages : ( 1 ) More fruiting wood may
be retained at pruning. (2) Since the
clusters are better distributed, more uni-
form exposure to light and air is obtained.
(3) Thinning, girdling (on Thompson
Seedless), and harvesting are facilitated.

runing • . . the type used depends on
the kind of grapes that will be raised

In general, pruning consists in remov-
ing canes, shoots, leaves, and other vege-
tative parts of the vine. Thinning is the
removal of flower clusters, immature
clusters, or parts of clusters. (The re-
moval of ripe fruit is harvesting.) Train-
ing consists chiefly in attaching the vine
and its growth to various forms of sup-
port. Shoots are the current season's
succulent top growth. Canes are matured
shoots. The trunk is the undivided body
of the vine. Arms are primary, secondary,
or tertiary branches. A spur is the basal
portion of a cane from one to four buds
or nodes in length. A fruit spur is one
that is intended primarily to bear fruit.
Renewal spurs are intended to produce
canes that may be used the next season
for spurs or fruit canes; and replacement
spurs are used to shorten or replace arms
or branches; renewal and replacement
spurs may or may not bear fruit. A fruit
cane is the basal section of a cane, eight
to fifteen buds long, used to produce the
crop on cane-pruned vines; it is always
removed at the following pruning. Water-
sprouts are any shoots that arise on parts
of the vine older than one year. Suck-
ers are water-sprouts that arise below
ground; the term is also frequently ap-

plied to water-sprouts from the trunk and
main branches.

The principles and practices of prun-
ing vines are discussed in more detail in
Extension Circular 89, Pruning Vinifera
Grapevines.

Functions and influence. Pruning
has three main functions: (1) to aid in
establishing and maintaining vines of a
predetermined form or shape, one which
will encourage productivity and which,
at the same time, will save labor and fa-
cilitate cultivation, disease and pest con-
trol, thinning, harvesting, and other
vineyard operations; (2) to distribute
the bearing wood over the vine, between
vines, and between years in accordance
with the capacity of the spurs (or canes)
and vines, in order to equalize produc-
tion and secure large average crops of
good fruit; and (3) to reduce or elimi-
nate the cost of thinning in regulating
the crop.

Pruning, with reference to the removal
of living parts, has two pronounced ef-
fects : it concentrates the activities of the
vine into the parts left; and it diminishes
the total capacity of the vine for growth
and fruit bearing. Correct pruning con-
sists in utilizing the first effect to the

[13]

extent required while avoiding the second
effect as much as possible.

Other things being equal, a heavily
pruned vine will produce fewer leaves
than one lightly pruned. It will also pro-
duce its maximum number of leaves and
maximum area of foliage surface later
in the season, so that the total annual
work done by the leaves will be less. In
consequence, smaller quantities of carbo-
hydrates, such as sugar and starch, will
be formed; and the amount available for
the nourishment of roots, stem, shoots,
flowers, and fruit will be less. This effect,
unless the crop is controlled by thinning,
is usually masked by the fact that the
lightly pruned vine produces a relatively
large crop; and, as the crop weakens the
vine to an extent comparable with the
effect of pruning, the actual production
of wood, foliage, and fruit by the lightly
pruned vine, over a series of years, may
be no more than that by the heavily
pruned vine. If the crop is restricted by
appropriate thinning, however, the lightly
pruned vine will usually produce more
crop and will grow better than the heavily
pruned.

Prune during the
dormant season

The chief pruning is done while the
vine is dormant, between leaf fall in the
autumn and the starting of growth in
the spring. The time of pruning within
the dormant period has little or no influ-
ence on the vigor of growth or production
of fruit the following season, if the vines
are not frosted after growth starts. Very
late pruning may, however, slightly delay

the time when growth begins. By pruning
when the upper buds on the canes have
grown an inch or two, one may retard
the starting of the lower buds (those left
on the spurs) as much as a week or ten
days, and these may escape damage if
frost occurs within that period. Only very
late pruning considerably affects the time
of starting growth; in most regions, the
differences caused by pruning at various
dates between December 1 and March 1
are negligible.

Summer pruning, which includes dis-
budding, suckering, pinching, topping,
and leaf removal, is used only for special
purposes, as explained on page 18.

Types of pruning
are described

The various styles of pruning used in
commercial vineyards in California may
be grouped into three main classes or
systems— namely, head, cane, and cordon.

Head pruning. In the head system
the mature vine has a vertical stem or
trunk, 1 to 3 feet high, bearing at its
summit a ring of arms or short branches.
At the ends of these arms, at each winter
pruning, are left spurs to produce the
shoots that will bear the next crop and
furnish canes for the next year's spurs.
Thus, this system consists of head train-
ing and spur pruning. The point or re-
gion where the trunk divides into, or
bears, the arms is called the head. (See
photo.)

The advantages of head pruning are
simplicity of form, ease of training, and
cheapness. The headed vine is the easiest
type to establish, largely because the

This shows typical treatment
of a cane-pruned vine on a
2-wire trellis. Cane pruning is
described in detail starting on
next page.

trunk is relatively short and upright. The
cost of support is relatively low. During
the developmental period, stakes are
necessary; but after five to ten years, the
trunks are rigid enough to be self-sup-
porting. Cross-cultivation is possible, a
feature that may be advantageous when
the control of noxious weeds is a problem.

The disadvantages of head pruning lie
chiefly in the depressing effect of severe
pruning on the growth and productivity
of the vines and in the massing of the
fruit within a small area. When crop is
controlled entirely by pruning, as with
most head-pruned varieties, the pruning
must be severe to prevent overbearing.

Head pruning suits most varieties that
bear well on short spurs. It is used for
most wine grapes, for the raisin Muscat,
and for a few table varieties, notably the
Tokay.

Cane pruning. In cane pruning, the
vine is given a trunk similar in form to
that in head pruning. The head of the
vine differs in being fan-shaped in the
plane of the trellis. Only two arms on
each side of the head are usually needed.
At each annual pruning, after the vines
are mature, fruit canes eight to fifteen
buds (2 to 5 feet) in length are retained
for producing the crop (fig. 5). The old
fruit canes are removed each year. The
production of canes for use the follow-
ing year is left largely to the renewal
spurs, usually two buds long and located
near the base of each fruit cane.

Cane pruning is necessary for varie-
ties, such as the Thompson Seedless, that
have mostly unfruitful buds near the base

This is an example of hori-
zontal, bilateral cordon prun-
ing on a 3-wire trellis. This
method of pruning is described
on page 16.

This is the result of head pruning— the least
expensive and most commonly used system.

of the canes. It also insures full crops with
varieties that produce very small clusters,
such as the Cabernet Sauvignon, the Reis-
lings, and the Pinots. Combined with ap-
propriate thinning to regulate crop, it
offers other advantages : the fruit may be
distributed over a large area; the tend-
ency of certain varieties, like the Muscat
of Alexandria and the Dattier, to pro-
duce shot berries (small, underdeveloped
berries without seeds) and straggly clus-
ters may sometimes be reduced. Since
there will be more clusters than are
needed for a crop, the grower may elimi-
nate the least desirable ones by thinning,
and improve the average fruit quality.
The disadvantages of cane pruning are

twofold: the tendency of most varieties
to overbear, with consequent production
of poor fruit, unless adequate thinning
methods are employed; and the high cost
of pruning and of supports— a trellis is
usually necessary. For raisin and wine
grapes the simple two-wire trellis is suf-
ficient, but for fine table grapes a wide-
topped trellis is better.

Cordon pruning. Cordon-pruned
vines have no definite head. The trunk,
which is much elongated either vertically
or horizontally, has arms at intervals of
8 to 12 inches over the greater part of its
length. In California the horizontal bi-
lateral form only is recommended. The
trunk rises vertically to a point about 8
inches below the supporting wire of a
trellis. At this point it divides into two
equal branches, which rise to the wire in
quarter circles and extend in opposite
directions along the wire to points half-
way to the adjacent vines on either side.
The bends should be smooth and regular;
the horizontal portions straight. No
shoots should be permitted on the bends
of the mature vines. The bearing units
are spurs on small arms located at regu-
lar intervals on the horizontal part of the
branches. They should, wherever possi-
ble, be on the upper side of the branches
or at least extend in an upward direction
if they originate elsewhere.

The fruit on horizontal cordon-pruned
vines is well distributed, with all clusters
hanging at about the same distance from
the ground— conditions favorable to uni-
form development and maturation of the
fruit. Some varieties that require long
spurs with head training bear fair crops
on spurs of normal length when pruned
by the cordon system.

The greater length of the trunk of the
vines makes the cordon the most labori-
ous and most expensive system to estab-

lish. Not only is more work required, but
the labor employed must be more skilled,
and a trellis or some other permanent
support is essential.

In California cordon pruning is com-
monly used only with certain table-grape
varieties, particularly Malaga, Red Mal-
aga, Ribier, and Emperor. It should also
be advantageous for the vigorous wine-
grape varieties that produce very large
clusters.

Bearing vines need
pruning every year

Head pruning. On a mature vine, the
number and length of spurs left the previ-
ous year, together with the size of the
canes and the number of clusters pro-
duced during the past growing season,
should be used as a guide in determining
the number and length of the spurs needed
on a vine. (The number of clusters pro-
duced may be learned by counting the
stubs left where the clusters were cut off.)

A vine that produced a good crop and
has canes of normal size should be pruned
to about the same number of spurs of
similar length (as measured by the num-
ber of buds) as the year before. If the
canes are abnormally large for the va-
riety, indicating that the vines were very
vigorous the previous summer, more
spurs, or longer spurs, or both, should
usually be left in order to utilize this
capacity in the production of fruit. If,
on the other hand, the canes appear weak
—that is, small for the variety— fewer
buds should be left. To reduce the num-
ber of buds, one may reduce the number
of spurs retained or may cut the spurs
shorter. Spurs retained from large or
vigorous canes should carry more buds
than those retained from small or weak
canes.

A good rule-of-thumb for the inexperi-
enced pruner to follow is to retain one

[16]

bud (not counting base buds) on spurs
that are the diameter of a lead pencil; 2
buds on spurs as large as one's little fin-
ger; 3 buds on those as large as the mid-
dle finger; 4 buds on spurs as large as
the thumb. Base buds, that are not to be
counted, include all buds within one-half
inch of the base of the cane. In general,
medium-sized canes— those proper for 2
or 3 buds— are the best.

The spurs should be so placed that the
form of the vine is maintained or im-
proved and the fruit uniformly distrib-
uted. Whenever possible, canes from near
the base of last year's spurs should be
used for the new spurs. The arms elongate
from year to year. When an arm becomes
too long it is shortened to a replacement
spur made from a water-sprout or other
suitably located cane.

Cane pruning. The renewal spurs
left the previous season should have pro-
duced two good canes apiece. On an
ideally shaped vine the uppermost cane
on the spur would be used for the fruit

cane, and the lower one cut back to two
buds to form the new renewal spur. Wher-
ever feasible, this practice should be
followed. If, however, enough good canes
cannot be obtained from the renewal
spurs, then canes arising near the base
of the old fruit canes, or even water-
sprouts, may be used for the new fruit
canes or renewal spurs.

The number of fruit canes needed
varies from one to six, according to the
size and total growth of the vine. The
length of these canes depends upon their
individual size: large ones (one-half inch
or more in diameter) may be left to a
maximum length of fifteen buds; small
ones should have proportionally fewer
buds. If the crop is to be regulated by
thinning, as with all table varieties when
cane-pruned, a standard number and
length of fruit canes may be adopted,
and the crop on each regulated according
to its vigor.

The renewal spurs should usually be
about one and one-half times as numerous

These are Ohanez vines, cane-pruned, and trained on an arbor. This type of training is usually
done more for its decorative effect than for its commercial possibilities.

[17]

as the fruit canes and should be placed
to maintain or improve vine's form.

Cordon pruning. Since the annual
pruning of the cordon vine consists in
cutting to spurs, it resembles head prun-
ing: in choosing the wood and estimating
the number of buds to be left, the pruner
proceeds in exactly the same way. To
maintain the capacity of the individual
arms at the same level, the length of the
spurs left must be regulated in accord-
ance with the size of the canes from which
they are made, as with head pruning.
Long spurs should be bent sharply at the
internodes or tied down to a horizontal
position to cause the lower buds to grow;
otherwise the arm may soon become too
long. Sometimes one-bud replacement
spurs at the base of the long fruit spurs
or farther down on the arm may be used
advantageously.

Pruning vines on arbors. The prun-
ing of vines on an arbor or a pergola
does not differ essentially from the prun-
ing of other vines. The form given to
the vine depends on the space to be cov-
ered and the fruiting habits of the variety.
Thompson Seedless and other varieties
that have mostly sterile buds on the basal
portion of the canes must be cane-pruned.
Such vines should be headed at or near
the top of the arbor. The pruning is the
same as described for the cane system.

Vines of varieties that bear well with
spur pruning should be trained and
pruned as multiple, horizontal cordons;
that is, each branch on the top, or side,
of the arbor should be treated as a cor-
don. After the vine has been made to
cover the required space, through the
gradual increase and elongation of
branches by the use of canes, spur prun-
ing is preferable. Where a high wall is
to be covered, the cordons at different
levels should be provided by alternating
high and low vines.

Summer pruning sends
growth where it's needed

Suckering, crown suckering, pinching,
topping, and the removal of leaves are
the operations in summer pruning. Suck-
ering— the removal of water-sprouts from
the trunk and from below ground— should
be done carefully and thoroughly in every
young vineyard and at least once each
year in every old one. As a rule, no water-
sprouts should be permitted on the undi-
vided portion of the trunk of mature
vines either above or below ground.

Crown suckering — the removal of
water-sprouts from the branches and
arms— should be employed with care.
Usually one may open the head of the
vine by judicious crown suckering in
order to improve the quality of the fruit
or to concentrate growth in parts where
it is wanted. To remove unfruitful shoots
in all cases, however, on the theory that
they are useless, is a mistake. The foliage
they produce nourishes the vine and
makes it more capable of bearing fruit.
Also, some shoots may be needed for use
as replacement spurs. The constant and
thorough removal of all water-sprouts
from the large branches and arms admits
the direct rays of the sun and causes
"bald-headed" vines, which are subject
to severe injury by sunburn.

Pinching — the removal of the grow-
ing tip of a shoot with thumb and finger-
is often useful in arresting the elongation
of very vigorous shoots. This operation
lessens wind damage and aids in develop-
ing young vines.

In topping, 1 to 2 feet is removed from
the end of a growing shoot, usually in
June or July. In very windy districts the
practice may sometimes be advisable, for
it may be better to cut off a part and save
the remainder than allow the wind to
break off the entire shoot. Since leaves
are removed, the practice weakens the

[18]

vine; and severe late topping may depress
the next crop by as much as 70 per cent.
Judicious removal of leaves sometimes
helps certain varieties to color; the opera-
tion opens the vines, permitting better
exposure of the clusters. If the leaves are
left on until the fruit has attained the
minimum sugar content desired, neither
the vine nor the fruit will be harmed. If
many leaves are taken away before the
fruit reaches the minimum sugar content

for harvest, ripening may be retarded.
To improve the coloring of the fruit, one
should remove only the leaves in the head
of staked vines and those on the lower
part of the north or east side of trellised
vines.

To aid in the production of fine table
grapes one may remove, soon after the
berries are set, any leaves that will rub
the clusters and any tendrils that may
intertwine the clusters.

ourtg grapevines require very care-
ful training during their first few years

The development of young vines in com-
mercial vineyards follows a rather defi-
nite procedure— the use of pruning and
disbudding to direct the growth, and the
use of stakes or trellises to maintain the
vine in the desired position. Usually four
years are required to complete the train-
ing.

The first year — help them
get good root systems

Throughout the first year, the main ob-
ject is to develop a good root system.
Cultivation and irrigation should be con-
ducted with this in mind. The frequency
of irrigation and the quantity of water
applied will depend upon climatic and
soil conditions. At least one irrigation,
where possible, in late spring or early
summer is always helpful in promoting
growth of the comparatively shallow
roots of the young vines. In hot climates
two, three, or more applications may be
needed. Late irrigation in the summer
should be avoided, because it may render
the vines liable to injury from early win-
ter frosts. Usually no pruning or training
should be done in the first growing sea-
son, except in region 5, where the vines
often may be trained during the first sum-

mer in the same way as described for the
second summer in cooler regions.

By the end of the first growing season,
the vines should have a well-established
root system and a well-matured top
growth. All of this top growth, except
the strongest cane, should be pruned off
sometime during the winter. The reserved
cane is then usually shortened to two or
three well-formed buds. The vines should
be staked or trellised at this time if not
earlier (before planting).

The second year — help
develop the trunk

The object of the second year's work
is to develop a single strong, well-matured
cane (with or without lateral branches)
from which to form the permanent trunk.
This is accomplished by disbudding in
such a way as to direct the whole grow-
ing capacity of the vine into a single cane.
Soon after the buds start and before any
have developed into shoots of more than
4 inches, all but one should be stripped
off. The shoot reserved should be the one
strongest and best placed for growing
vertically near the stake. As this shoot
grows, it should be tied loosely to the
stake in order to keep it straight and ver-
tical. It is first tied when 8 to 12 inches

[19]

■ if
1

i-M /

Training during the second summer. Left: before the second disbudding. The two center photos
show method of tying shoots. Right: low laterals pinched at p; main shoot at m.

long and is re-tied once or twice more
until it reaches the height at which the
trunk divides; all other shoots should be
removed from the old wood as they begin
to develop. Laterals that grow on the re-
served shoot should not usually be re-
moved. If those below the middle of the
shoot show signs of developing as rapidly
as the main shoot, they should be pinched
back or removed. The main shoot should
be pinched when it has grown 8 to 12
inches above the point at which the trunk
will divide to form the branches or arms.
Up to this time the vines under all

pruning systems are handled exactly
alike. Beyond this point the training of
the cordon differs from that of the head
and cane systems, which remain alike for
another year.

With vines to be head- or cane-pruned,
all laterals on the upper half of the shoot
are usually allowed to grow without
pinching.

To form the bilateral horizontal cor-
don, two laterals (or the main shoot and
one lateral) are selected to form the two
branches of the vine. All other laterals
are pinched back or, if vigorous, are re-

[20]

moved entirely. The point where the trunk
divides should be 6 to 10 inches below
the wire of the trellis that will support
the cordon. When the laterals have made
18 to 24 inches' growth, one of them is
tied in each direction on the trellis. As
they continue to grow, they are kept
straight by being tied loosely to the wire.
No ties are placed on the portion of the
shoot that is elongating— a few inches to
a foot or more from the tip, according to
the rate of growth. The laterals are
pinched after they have grown about 18
inches beyond the halfway point to the
next vine.

At the end of the second summer, vines
that are to be head-or cane-pruned should
have developed a strong cane, which will
form the permanent trunk, and several
laterals on the upper half of the trunk
cane. The trunk cane is cut off at the first
node above the level where the head is
desired. The cut should be made through
the node in a way that destroys the bud
but leaves the enlargement; this tech-
nique facilitates tying. All small laterals
and all laterals below the middle are re-
moved. On exceptionally large vines, one
to three laterals over %g inch thick on
the upper half of the cane may be cut back
to one, two, or more buds, according to
their diameter. These will act as fruiting
spurs and will help to develop the head
rapidly. A single fruit cane may be left
on very vigorous cane-pruned vines.

Vines on which the trunk cane is less
than % 6 inch thick at the desired height
of the head should usually be cut back to
two buds as at the first winter pruning.

A single hitch, two half hitches, or a
clove hitch is made around the trunk cane
just below the enlargement of the node
that was cut through, and the string is
taken twice around the stake and tied
over the trunk cane as tightly as possible
with a firm square knot. A loose tie is
then placed around the stake and the
trunk cane at about the middle; it must
not pass around the cane between the cane
and the stake, or the vine may be girdled.
See photo, page 22.

Cordon vines at the end of the second
summer should have the trunk and the
laterals for the branches fairly well
formed. At the second winter pruning the
branches should be cut back to a place
where they are at least % mcn thick. If
they have grown sufficiently, they may be
cut at a point halfway to the adjoining
vines. If the canes are not large enough
to reach at least 12 inches along the wire
beyond the bend, they should be cut back
to within one or two buds of the point
where the trunk was divided, and more
vigorous canes grown the next year. All
laterals on the trunk below the point of
branching are removed entirely; and un-
less the vines are extremely vigorous, no
spurs are left on the branches.

The completed trunk and branches of a horizontal, bilateral, cordon-pruned vine tied to the
wire during the second (or third) winter of its training, as described on page 20.

♦«~*v-

The third year — help
develop branches

The vines in the third summer will bear
crops of varying amounts according to
their size; the main object is, however,
to develop the permanent branches. All
shoots that start on the lower half of the
trunks of head- and cane-pruned vines
should be removed before they make
much growth. Shoots starting on the up-
per half of the vine may be allowed to
grow without interference except that the
most vigorous may be tied or pinched if
there is danger that the wind may break
them off.

At the third winter pruning of a head-
pruned vine, enough canes should be
reserved and cut back to spurs to bear
whatever crop the vine can carry without
injury to its vigor or to the proper matur-
ing of the grapes. The number will usually
be three to six, according to the total
growth. Each spur should be cut back
to two, three, or four buds, according to
the size of the cane from which it is re-

tained. These spurs should be as near the
top of the vine as is practicable.

On cane-pruned vines one or two fruit
canes, each 8 to 15 buds long, according
to their size, should be left and tied to the
supporting trellis. To supply canes for
the following year, one should leave two
to four renewal spurs, all as nearly as
possible at the desired height of the per-
manent arms into which they will develop.

Cordon vines require much more care.
When the vines start growing in the
spring, the vineyard should be gone over
several times, and the shoots growing on
the underside of the branches rubbed off.
This operation will remove about half
the shoots and leave the other half, spaced
6 to 12 inches apart, on the upper side.
At the same time, all shoots starting on
the trunk or on the bends of the branches
should be removed.

As the shoots that are retained grow
at uneven rates, some will soon be much
longer than others. These long shoots are
usually either near the bends or at the

This shows steps in training during the third summer, for either head or cane pruning. Note
that only the four lower buds are removed, as shown in the photo on the right.

[22]

ends of the branches. They should be
pinched as soon as five or six leaves have
formed. This pinching will check their
growth and allow the weaker shoots to
catch up with them.

On vines that do not extend the full
length, a shoot is allowed to grow from
near the end of the incomplete branch
to complete it. This shoot should be tied
to the wire to make the extension of the
branch as straight as possible; a shoot
from the underside of the branch is usu-
ally best.

As soon as the shoots are long enough,
several from near the end of each branch
must be tied to an upper wire. Otherwise
the weight of all the shoots, together with
that of the fruit, will turn the branch com-
pletely over, leaving the upper side bare
and the shoots all pointing downward.
If this trouble occurs and is not soon cor-
rected, the vine can never be made into
a good cordon.

Overbearing must be prevented. Usu-
ally, if the disbudding has been done as
described, enough potential fruit will
have been removed. If, however, the
young vines bear more fruit than they
can probably develop to good quality,
some of it should be removed by thinning.

At the third winter pruning, spurs one
to three buds long are retained at regu-
lar intervals, 8 to 12 inches, spaced along
the upper side of the horizontal portions
of the branches. All other canes are re-
moved. All old ties on the trunk and
branches must be cut, and the vine retied
to make the horizontal portions of the
branches as straight as possible. If deep
sags are left, vigorous growth cannot be
maintained on the sagging parts.

The fourth year on — the
crop becomes important

In the fourth and subsequent years the
aim is to perfect the structure of the vine

so that essential operations will be facili-
tated and the vines will bear maximum
crops of best-quality fruit. Head-pruned
vines will be developed gradually into
symmetrical forms. The heads of cane-
pruned vines will be developed fan-
shaped in the plane of the trellis, and
thus will interfere as little as possible with
cultivation. The arms of bilateral cordon-
pruned vines should be uniformly spaced
over the horizontal portions of the
branches; one should maintain them up-
right by tying green shoots to the top
wire, especially until the branches are
large enough to resist the twisting effects
of the growth and crop that might be
heavy on one side of the trellis; they
should be kept at the same height and at
uniform vigor by careful pruning and
judicious pinching.

During the summer all water-sprouts
should be removed from the trunk below
the lowermost arm on head- and cane-
pruned vines. All water-sprouts, except
those needed in developing new arms, are
removed from the branches and trunks
of cordon-pruned vines.

Vines that grow slowly may lag be-
hind this program, whereas very vigorous
vines in hot regions may be ahead of
schedule. In either case the adjustment
is usually made at the first or second win-
ter pruning. Weak young vines may be
cut back to two or three buds the second
winter, a practice that delays the subse-
quent operations by one year. With very
vigorous vines, the four years' work of
developing may be completed in three.

Thinning of flower-clusters,
clusters, or berries

Three distinct types of fruit thinning
are used on grapes— flower-cluster thin-
ning, cluster thinning, and berry thin-
ning. All types of thinning owe their
effectiveness to a reduction in the number

[23]

This photo shows a closeup of a single cane of a Muscat vine with the clusters at the proper
stage of development for flower-cluster thinning. The operation is described below.

of flowers or fruits and to the better nour-
ishment of those that are left. Since each
type of thinning, however, has a distinct
purpose, the method chosen depends on
the type of fruit produced by a variety
or a vineyard.

Flower-cluster thinning. The clus-
ters of rudimentary flowers of the grape
appear with the leaves in early spring.
The individual flower parts continue to
develop until blooming occurs (from 6 to
8 weeks). The removal of some flower
clusters soon after they emerge, with no
removal of leaves, improves the nutrition
of those remaining. As a result, a better
set of normal berries may be secured.
Flower-cluster thinning is therefore use-
ful on varieties that have loose or straggly
clusters, or which set many shot berries
with the usual pruning, such as the Mus-
cat of Alexandria and Dattier. For best
results the vines should be long-pruned
(long spurs or fruit canes) and thinned
as soon as possible after the flower clus-

ters appear. This type of thinning should
never be used on varieties that produce
compact clusters, like the Tokay.

Cluster thinning consists in the re-
moval of entire clusters soon after the
berries have set, after blooming. The most
widely useful of the three types, it is the
easiest and best means of reducing the
crop on overloaded vines of wine- and
raisin-grape varieties to insure that the
remainder will develop and mature prop-
erly. By leaving enough fruiting wood
(spurs or canes) at pruning time to pro-
duce a good crop in poor years and then
reducing the overload in good years by
cluster thinning, one may secure large,
regular crops almost every year.

Cluster thinning, since it is not done
until after blooming, does not influence
the number of berries that set; and since
entire clusters are removed it does not
appreciably change the character of those
retained. By improving the nutrition of
the fruit that is left, cluster thinning en-

[24

hances the size and coloring of the berries
and hastens maturity. One may further
improve the average quality of table
grapes by retaining only the best clusters.
At thinning time the clusters of table va-
rieties should be disentangled from one
another or from shoots around which
they have formed. This operation will
prevent damage to many fine clusters dur-
ing harvest.

Berry thinning consists in removing
parts of the cluster, usually by cutting off
the end of the main stem and several
branches of the cluster, or by cutting off
enough of the main stem to leave only
the desired number of berries. This
method can improve quality only when
an overabundance of berries makes the
clusters too compact or when overlarge
cluster parts interfere with proper color-
ing and maturation. In the improvement
of quality, therefore, its usefulness is
limited to varieties that set very compact
or very large clusters. Berry thinning

usually changes the character of the clus-
ters materially; it always reduces their
size and sometimes alters their shape.
The thinning should be done as soon as
possible after the drop of berry forms
(flower receptacles) that normally fol-
lows blooming— that is, as soon as the
berries have set.

Girdling of trunk,
arm, or cane

Girdling, also called "ringing," con-
sists in removing a complete ring of bark
Ys to i/4 inch wide from the trunk or from
an arm or a cane below the fruit which
it is intended to affect. As a result, the
carbohydrates elaborated in the leaves
will accumulate in the parts above the
wound, including the clusters of blossoms
or fruit, and will materially influence
their development. The stage reached by
the grapes at the time of girdling will
largely determine the nature of the re-
sponse.

These are clusters of Black Corinth— the one on the left is from a vine that was girdled while
in bloom; the ones on the right are from an ungirdled vine.

[25]

To improve set of berries. Girdling
done while the grapes are in bloom in-
creases the number of seedless berries
that set, but does not cause any additional
seeded berries to form. It improves the
yield of the Black Corinth, which, with-
out girdling, produces small, straggly
clusters consisting of tiny seedless berries.
Girdling at this time increases the num-
ber as well as the size of seedless ber-
ries. The Black Corinth is universally
girdled during the blooming period.
Trunk girdling is favored over girdling
the arms or fruit canes because it affects
the whole vine uniformly. The trunks
of the Black Corinth tend, furthermore,
to remain relatively small, and trunk gir-
dling is cheapest. Girdles % 6 inch wide
are adequate. Wine-grape varieties, like
the Pinot Chardonnay, which in occa-
sional vineyards produce only straggly
clusters, can be made to yield larger crops
by girdling. The additional fruit consists
entirely of seedless berries.

To increase berry size. A complete

girdle that is open and effective during
the period of most rapid growth of the
berries, which occurs within a few weeks
after blooming, increases the size of seed-
less berries 30 to 100 per cent, but of
seeded berries usually less than 20 per
cent. Figure 13 reproduces, in natural
size, photographs of Thompson Seedless
berries from girdled and ungirdled vines.
If the operation immediately follows the
normal drop of berry forms, after bloom-
ing, the greatest increase in size of berries
is obtained with little or no influence on
the number.

Thompson Seedless vines for produc-
ing table grapes are, therefore, girdled
as soon as possible after the normal drop
of the berry forms. If the girdling is done
too early— before the normal drop is
complete— the clusters become too com-
pact. If it is delayed more than a few days
after the normal drop, the increase in
berry size is less. The girdling may be
done on either the trunks or the fruit
canes with almost equally good results.

Thompson Seedless berries, about actual size. Top left: girdled but not thinned; top right: girdled
and berry-thinned; lower left: not girdled, but thinned; lower right: berry-thinned, not girdled.

The girdles are usually made % G or %
inch wide and heal over in 3 to 6 weeks.

Thinning is nearly always necessary
when Thompson Seedless are girdled.
The increase in total crop, without thin-
ning, is roughly proportional to the in-
crease in berry size; hence vines that are
girdled but not thinned are nearly always
overloaded, with consequent poor quality
of fruit and weakening of the vines.
Thompson Seedless clusters from un-
girdled vines are normally well filled or
compact. Since girdling increases the size
of the berries but not the length of the
stem parts, it increases the compactness
of the clusters, often making them too
compact.

The method of thinning will be deter-
mined in each instance by the character
of the clusters. Cluster thinning (see p.
24) should be used to eliminate the least
desirable clusters— those too compact,
too small or too large, misshapen, or
otherwise defective— leaving the required
number of the best. Any of the remainder

that are too compact must be berry-
thinned (see p. 25). The forked-tip ends
of all retained clusters should be cut off.
In short, the thinning usually combines
the cluster and berry methods.

Seeded varieties show less response to
girdling. Although shot (seedless) ber-
ries of these varieties are improved in the
same manner as are the berries of seedless
varieties, the normal-seeded berries are
increased only slightly in size. Greater
benefits may be obtained by thinning
alone when a method suited to the va-
riety is employed. Girdling to enlarge
the berries of normal-seeded varieties is
of doubtful economic value and is not
recommended.

To improve color and to hasten
ripening, the girdles must be open and
effective during the early part of the rip-
ening period. Even then the desired result
cannot always be obtained. The seedless
varieties— Thompson Seedless in particu-
lar—are influenced in this respect but
little, if at all. On the other hand, the

Thompson Seedless clusters. Left: unthinned clusters from vines that had been girdled; right:
berry-thinned clusters from vines that had been girdled. Note fullness of clusters on the left.

coloring of Red Malaga and Ribier can
often be improved. The rate of ripening
of most seeded varieties— Malaga, Mus-
cat, Red Malaga, Ribier, and the like-
may be accelerated. Girdling to hasten
ripening and to improve coloring should
be done just before ripening starts, when
the first traces of color appear in the
fruit. The best results are obtained from
vigorous vines having only a light crop.
With a normal to heavy crop, often no
response will be obtained.

Girdling to hasten ripening is of doubt-
ful economic value except sometimes in
very early districts where a few days'
advance in maturity may mean a great
difference in price— sufficient to compen-
sate for the reduced crops, the added ex-
pense, and the risk of failure.

Making the girdle. Various types of
double-bladed knives are used to girdle

These are tools commonly used in girdling.
Left: double-bladed trunk girdler; right: cane-
girdling pliers.

the trunks; a specimen is shown in the
photo below. Work done with an ordinary
single-bladed knife is usually less perfect
and more expensive. Cane girdling is best
performed with girdling pliers that have
double blades on each side. With pliers,
such as those shown, in position on a
cane, one should cut through the bark
by pressing on the handles, then re-
lease the pressure, rotate the pliers on
the cane, and cut another section of the
ring by squeezing the handles. This proc-
ess continues until the cane is completely
encircled. When the ring of bark has been
cut completely around the cane, it is
loosened by rotating the pliers, under
slight pressure, around the cane. The
bark removed will stick between the
double blades but with further use of the
tool, will pass on through between them.
A spacing of Z /\Q mcn between the double
blades is recommended.

Weakening effect. Because girdling
stops the downward movement of organic
food materials past the wound until after
healing, the lower parts of the vine, par-
ticularly the roots, are undernourished
while the wounds are open. The roots
cannot explore new soil areas to get ade-
quate amounts of water and other mate-
rials. The top growth is checked, and the
leaves tend to become yellowish. The
longer the wounds remain open, the more
serious is the weakening effect. Trunk
girdles that fail to bridge across during
the growing season cause the death of
the vines. Cane girdles that fail to heal
are less serious. Girdles made during or
soon after blooming, and not more than
y± inch wide, will usually heal in 3 to 6
weeks, whereas those made later or cut
wider or reopened to influence ripening
will heal more slowly and have a more
weakening effect.

Good cultural care, particularly in ir-
rigation and in thinning to regulate the

[28

crop, will make the girdle less weakening
to the vine. The frequency of irrigation
should be doubled while the wounds are
open.

Overbearing of girdled vines must be
avoided— with Black Corinth, by pruning ;
with Thompson Seedless and all other
table varieties, by thinning to the extent
that the girdled vines will not have more
than two thirds of the maximum crop
they could mature if not girdled.

If properly thinned and well cared for,
Thompson Seedless vines may be girdled

year after year. One experimental lot of
twenty mature vines in Stanislaus County
was girdled and thinned for eleven con-
secutive years with no apparent decrease
in crop or growth.

In making the girdles, one should re-
move only the bark— the tissue outside
the cambium layer. Cutting deeply into
the wood is serious; it destroys many
of the most active conducting vessels in
the outer layers of wood and thus causes
a lack of water above the point where it
was girdled.

ultivation practices will vary with
the needs of the particular vineyard

Cultivation is practiced in most com-
mercial vineyards, but it varies widely in
frequency and depth. It is beneficial in
some respects: the purposes set forth
in the next paragraph are often accom-
plished by this means more easily, more
cheaply, and more efficiently than by any
other. It may, however, be detrimental;
it often breaks down a favorable soil
structure and develops puddled surface
soil, or compacted subsurface layers
(plow sole). The present trend is to cul-
tivate vineyards often enough and deep
enough only to secure the desired results.
Unnecessarily frequent and deep cultiva-
tion should be avoided.

The general purposes of vineyard
cultivation are: (1) to destroy weeds;
(2) to facilitate irrigation, pest control,
harvesting, or the drying of raisins; (3)
to prepare a seedbed for covercrops; (4)
to incorporate covercrops and manures
into the soil; and (5) to aid, temporarily,
in the absorption of water where other
vineyard operations have compacted or
puddled the surface soil.

Weeds must be kept under control. In
nonirrigated vineyards in California,
control means complete elimination of

weeds soon after the winter rains are over
and before the weeds have robbed the
soil of moisture needed to carry the vines
through the rainless period. Where ample
water is furnished throughout the sum-
mer, either by irrigation or by summer
rains, control means that the weeds are
not allowed to compete seriously with the
vines for soil nutrients, nor to interfere
with other vineyard operations. Clean
cultivation is not everywhere practiced
or advised.

Cultivation of itself does not conserve
soil moisture. Evaporation from the sur-
face dries out the top 4 to 8 inches of
soil, whether cultivated or not. In a well-
drained soil, moisture below the upper
8 inches is removed mainly by roots, not
by evaporation from the soil surface. In
tests comparing water removal by plants
with water removal by surface evapora-
tion, a tank of soil in which wild morn-
ing-glory was grown lost 120 pounds of
water in 23 days, whereas a similar tank
of bare, uncultivated soil lost only 57
pounds in over four years. Although this
latter tank was not irrigated after an ini-
tial wetting, it still contained available
water at the end of the four-year period.

[29]

Cultivation in a vineyard does conserve
moisture by destroying weeds, but only
in that way. Destroying the weeds by
other means is equally beneficial.

Furrows or ridges are needed to dis-
tribute irrigation water effectively. They
interfere, more or less, with harvesting
and especially with the drying of raisins
between the rows. If the raisins are to be
dried on paper trays, an almost essential
step is to smooth the soil by cultivation
and by dragging, before harvest. In vine-
yards of table and wine grapes the rough
ground is less objectionable, although a
light disking is sometimes desirable to
reduce the roughness of the soil and to
knock down the high weeds. Extensive
stirring of the soil in table-grape vine-
yards in preparation for harvesting is
avoided, to reduce dust on the fruit.

Where covercrops are planted to im-
prove the soil or to prevent destructive
erosion, cultivation is usually necessary
to prepare a satisfactory seedbed, with-
out which one cannot obtain a good
stand. Cultivation is also needed to in-
corporate the covercrop into the soil, if
for no other purpose than to prevent fires.
Fertilizers, other than nitrogen, tend to
be "fixed" near the surface. To be useful
to the vines, such fertilizers must usually
be placed, by mechanical means, below
the depth of ordinary cultivation:

Breaking up a compacted, or puddled,
surface layer by cultivation may increase
permeability of the soil to water, but this
effect lasts for only a short time. Repeated
cultivation tends to decrease permeabil-
ity. If left undisturbed, the natural chan-
nels formed by such agents as earthworm
burrows, cracking of the soil, and decay
of roots will enable the soil to absorb
water more rapidly than if these natural
channels were broken up by tillage. Cul-
tivation, particularly when the soil is wet,
tends to form plow sole— a more or less

impervious, compacted layer just below
the depth of tillage. The probability of
forming a plow sole may be lessened if
one gives only the needed cultivations,
when the soil is dry enough not to be
compacted by the implement. When a
plow sole has been formed, deep tillage
is often used in an attempt to overcome
it; but often the best remedy is to leave
the soil untilled, or to give infrequent,
shallow cultivations when the soil is not
wet. Wetting and drying of the soil, and
undisturbed plant roots may be more ef-
fective than deep tillage.

In unirrigated vineyards. The only
water available to the vines throughout
most of the growing season is that stored
in the soil from the winter rains. Any
weeds allowed to grow in the vineyard
after most of these rains have fallen will
use part of the water; hence the winter-
and spring-growing weeds and covercrop
should be destroyed soon after the winter
rains are over. The growth of summer
weeds must be prevented. Since cultiva-
tion is usually the most practical means
of destroying or preventing weeds, unir-
rigated vineyards are cleaned up in early
spring as soon as the soil is dry enough
to work. The winter covercrop— to this
time beneficial in reducing erosion and
preventing a loss of nutrients by leach-
ing—is incorporated into the soil by plow-
ing or disking. Cultivation is repeated
often enough to destroy or prevent fur-
ther weed growth. In the absence of
perennial noxious weeds, such as morn-
ing-glory and Johnson grass, cultivation
usually may be discontinued as soon as
the surface soil becomes too dry for seed
germination; but, where perennial weeds
are present, it must be continued as late
and as often as is necessary to control
them. The method of cultivation is rela-
tively unimportant as long as it eliminates
weeds, discourages erosion, and does not

[30]

injure the vines. A wet, plastic soil, which
may be puddled or packed by the imple-
ment, should not be worked. Rarely
should cultivation go deeper than 6
inches.

In irrigated vineyards the conserva-
tion of water is less important than it is
in unirrigated ones, because additional
water may be supplied to replace that
removed by both vines and weeds. Irri-
gated vineyards are usually cleaned up
in the spring, and subsequent weeds are
controlled during the period of rapid vine
growth in order to reduce or eliminate
the competition for soil nutrients. After
early summer or midsummer, if enough
irrigation water is available, weeds are
controlled mainly to prevent interference
with various operations. In raisin vine-
yards, where natural sun-drying between
the rows is practiced, the soil between the
rows is leveled and smoothed by cultiva-
tion and by dragging, in order to prepare
a place for the trays. Often, in table-grape
vineyards, cultivation is discontinued in
early summer or midsummer, and a cov-
ercrop of grasses or other plants is al-
lowed to grow; the same furrows or
ridges are used repeatedly for irrigations.
Many growers claim that use of the sum-
mer covercrop enables them to produce
better table fruit than is possible with
clean cultivation since it tends to check
vegetative growth of the vines earlier and

thereby induces earlier sugaring and
coloring of the fruit.

Tillage equipment should
be rather versatile

Plows, disks, chisel-tooth cultivators,
harrows of various kinds (including the
revolving and spring-tooth types), and
plank or steel drags are useful in cultivat-
ing between the rows. The choice of tools
is governed by the nature of the soil, the
power available for pulling the imple-
ments, the distance between the rows, the
nature of the winter covercrop, the man-
ner of pruning-brush disposal, and the
operator's preference. The same tools will
not serve under all conditions. In close-
planted vineyards, where the rows are
spaced 8 feet or less, the moldboard plow
is the main implement for the spring
cleanup. Where a heavy winter covercrop
grows in close-planted vineyards, the soil
is generally turned toward the vines by
shallow plowing, to cover the weeds in
the row, as soon as soil conditions permit
after the heavy winter rains are past
(March or early April). Spring rains
often produce another crop of grasses
and weeds after the first plowing. When
the spring rains are mostly over, but be-
fore the land becomes too dry to be
worked easily, the soil is turned back
to its original position by a second,
slightly deeper plowing, and then is
smoothed by harrowing. Later cultiva-

Tractor-drawn disk, with
one right- and one left-
hand Kirpy plow attached
to the back corners, for
getting the areas between
the vines. Such a tool re-
quires skilled operators.

Two Molley plows at-
tached to a tractor-drawn
disk. These plows eliminate
the need for single plowing
ahead of the Kirpy plows.
This is part of the equip-
ment in the photo on page
31.

tions are usually done by disk, weed cut-
ter, or spring-tooth harrow. The double
plowing may, at first thought, seem un-
necessary; but thus far no easier or
cheaper method has been found. Disks
small enough for such close-planted vine-
yards usually cannot chop up a heavy
covercrop so economically as plowing
can turn it under.

Vineyards with rows 10 feet or more
apart are seldom plowed. The spring
cleanup and practically all of the sum-
mer cultivation are done by disking.
Large, heavy disks will handle covercrops
of almost any size and will also chop up
the prunings that are incorporated into
the soil along with the covercrop. To pre-
vent such disks from cutting too deeply
for summer cultivation, spools, which
limit the depth of cutting, are often placed
on the axles between the disks.

Some vineyards with rows 8 to 10 feet
apart are disked ; others are plowed. The
tendency is toward disking where wide
spacing, light soils, and light winter cov-
ercrop growth occur; and toward plow-
ing where the opposite conditions exist.
If plows are used, the pruning brush in
the vineyard must be removed, or burned,
or shredded.

With head-pruned vines and square
planting (the rows and the vines in the

rows spaced the same distance) , cross-cul-
tivation—cultivating in both directions-
is frequently used to clean the spaces
between the vines in the rows. With trel-
lised vines or avenue planting (rows
spaced farther apart than the vines in
the rows), and often even with square
planting, the vine rows are cleaned up
with special tools. Of these tools, the
Kirpy-type plow, sometimes also called
French plow, is the most common. It may
be drawn by a horse or a mule; or two
plows, one right hand and one left hand,
may be drawn by a light tractor, or
hitched behind a disk, the operators rid-
ing on sleds. A very small amount of
hand-hoeing is usually needed to remove
the islands of broken but unturned soil
immediately adjacent to the vines.

For the Kirpy-type plow to work best,
the strip of unstirred soil underneath the
rows must not exceed 18 inches (prefer-
ably 12). Bordering the strip on either side
should be a furrow, or depression, into
which the soil from beneath the row can
be turned. The ordinary disk, operated
by a skillful tractor driver, will go close
enough if the vines are headed high and
the rows are straight. Many vineyards
do not meet these requirements. The Mol-
ley plow, attached to the back corners of
a 4-gang disk, is designed to reach under

[32

lowheaded vines about 8 or 10 inches be-
yond the rigid frame of the disk. This
device consists of 1 or 2 disks mounted
on a low frame which is pivoted in its
attachment to the disk, or plow. The
frame is streamlined and the cutting disks
are shielded over the front and top to
prevent damage to the vines or stakes.

Used alone, without the Kirpy, the Mol-
ley does fair work if the vineyard is cross-
cultivated. Used in only one direction, it
is inadequate. It does, however, enable
the tractor operator to drive close to the
vines (in preparation for the Kirpy
work) without great danger of damaging
them severely.

hemical weed control may sometimes
be used instead of usual cultivation

To avoid the ill effects of cultivation
(impaired soil structure, poor penetra-
tion of water, destruction of roots in the
top soil, and dust on the fruit), some
growers have experimented with sprays
of oils and other chemicals for weed con-
trol. Practical and economical results
have been achieved without serious in-
jury to the vines. At present the best spray
material is a light oil, such as Diesel fuel,
to which has been added a quantity of
the aromatic compounds and other im-
purities removed from petroleum in the
refining processes. Orchard-heater oil has
been used with good results in citrus
groves of southern California. Where
weeds are controlled entirely by oil spray-
ing, a permanent system of ridges or
basins is constructed for irrigation. Other
projects combine oil sprays with cultiva-
tion ; the oil is used in the row or between
the rows after midsummer, and most of
the spring cleanup and early-summei

weed control is done by cultivation. The
quantity of herbicide oil required varies
from as little as 15 to 20 gallons per acre
per application for spraying the rows
only, to 60 to 150 gallons per acre per
application when it is desired to cover
the entire area.

Weed control by spraying is more
practical in vineyards in which the vines
are supported on high trellises or arbors,
where the weeds can be sprayed without
also spraying the vines. It is impractical
in vineyards of low-growing vines.

Spraying the entire area of a vineyard
usually costs more than killing the weeds
by cultivation. Where the weeds are con-
fined to the strip of soil beneath the row,
or to irregular patches of a relatively
small area, however, spraying may be
more economical than cultivation. Spray-
ing is usually cheaper and more effective
than mid-summer hoeing, and may be
used as a substitute for that operation.

oil erosion is a hazard to be guarded
against in many California vineyard areas

On rolling lands in semiarid regions,
and even on gentle slopes in humid re-
gions, soil deterioration is mainly the
result of soil erosion. The erosion may
be insidious, passing unnoticed for some
years, but ruinously cumulative in the

end, as it is with sheet erosion; or it may
be spectacular, as it is when gullies are
deeply cut, often by a single storm.

When rain falls faster on the unpro-
tected surface of a soil than it can be
absorbed, the pelting rain stirs up the

[33]

surface soil in the water; and then the
soil particles, suspended in the water, run
off in surface drainage. This is sheet ero-
sion. It does not occur if the rain falls
so slowly that none runs off the surface,
nor if the surface is covered by vegeta-
tion, or otherwise, to break the pelting
force of the raindrops. Gullies are made
by the rapid flowing of relatively large
quantities of water. Gully erosion is re-
duced or eliminated if the flow is spread,
through vegetation, or if the velocity is
slowed, through vegetation, cross-slope
collecting ditches, or check dams.

Covercrops help
avoid erosion

The judicious use of covercrops in
vineyards on land subject to erosion
cannot be too strongly advised. The cov-
ercrop is most valuable if it is well estab-
lished and growing during periods of
heavy rain ; but it is still effective if heavy
rains fall in the spring after a light disk-
ing has checked or killed the covercrop
plants in preparation for the spring
cleanup.

Covercrops serve in at least three ways
to reduce or prevent erosion. First, as
has been pointed out, the top growth
covers and protects the surface, breaking
the force of the rain and slowing the flow
of the surface runoff. Second, the roots
bind the soil, more or less, with fibers
that tend to hold it in place. Third, cover-
cropping, after a year or two, increases
the rate of water penetration. The roots,
on decaying, leave channels through the
plow sole which reach deep into the sub-
soil. Further, the coarse vegetable matter
in the soil makes the surface more porous.
In a cover experiment at Davis, a 6-inch
irrigation disappeared from the surface
of a covercropped basin in less than 24
hours, whereas across a levee, in an ad-

jacent clean-cultivated check, the time
required was a week.

The covercrop may consist of native,
self-seeding plants, such as grasses, wild
mustard, bur-clover, or filaree; or of
sown grasses and legumes. Whatever the
plants, they must be established early in
the rainy period, so that the soil is cov-
ered with vegetation before surface run-
off is likely to occur. Native plants, and
also plants that are broadcast-seeded,
grow over the whole area— between,
around, and into the vines. Since the
cleaning up of a vineyard that has heavy
weed growth close to the vines is expen-
sive, the cost of the spring cleanup has
discouraged many vineyardists from the
use of covercrops. Most of the extra cost
is avoided, however, and most of the
benefits in preventing soil erosion are
still realized, if the covercrop is sown in
strips between the rows. For this purpose
a mixture of grain and vetch is excellent.
About 25 pounds of oats or barley and
20 to 30 pounds of purple vetch per acre
are drilled between the rows in one direc-
tion in strips 4 to 8 feet wide, according
to the distance between the rows. The soil
in the row is left unseeded, hence remains
relatively clean. In California the seed is
drilled into the dry soil at any time after
midsummer; but it does not start to grow
until the fall or early winter rains. Except
on fertile areas not already eroded, a light
application of fertilizer may be needed
the first two or three years to stimulate a
rapid early growth. One hundred pounds
of ammonium sulfate per acre, or its
equivalent in nitrogen (about 20 pounds)
in some other form of fertilizer, is usu-
ally adequate; occasionally phosphorus,
or potassium, may be needed also. The
fertilizer is best drilled into the soil by
means of an attachment on the seed drill.
The strip of heavy vegetation thus ob-
tained serves almost as well as a complete

[34]

cover in preventing serious soil erosion ;
and it interferes practically not at all with
normal vineyard operations. In unirri-
gated vineyards the covercrop must be
destroyed by disking or plowing as soon
as the heavy winter rains are past. If a
downpour should unexpectedly occur
after the covercrop is worked in, the
presence of the straw and the roots will
still largely prevent any damaging ero-
sion.

And so does contour
planting

Contour planting, as discussed here,
means planting in rows running across
the slope on a grade or fall of about 1%

feet in 100 feet. It is practical to contour
plant land which has a slope of 2 to 10
feet per 100 feet— with a greater slope
it becomes very difficult to control the
implements in cultivating.

With across-the-slope planting to grade
and with the principal cultivation being
in the direction of the rows, erosion is
markedly reduced. Management of a well-
planned vineyard planted to contour is
as easy as that planted on the square.

Land of such incline that it cannot be
farmed across the slope should not be
used for vines. To construct terraces on
land of this type is very costly and the
management of such plantings is beset
with a great many problems.

On level land they
may or may not help

Much has been written concerning the
importance of organic matter and the fer-
tilizing value of leguminous covercrops.
Soils rich in organic matter are usually
fertile, largely because they contain more
nitrogen. In relatively cool, humid re-
gions the humus (decayed organic mat-
ter) content apparently can be increased
by farming practices that incorporate
much vegetable material, such as green-
manuring crops, into the soil. In warm
arid and semiarid regions, however, the
destruction of organic material by bio-
logical processes is so rapid that accumu-
lation in well-drained soils is almost
impossible. Apparently, furthermore,
much of the benefit attributed to in-
creasing the organic content by the use
of covercrops may really result from pre-
venting or reducing soil erosion, and by
improving the penetration of water. This
reasoning is supported by experimental
evidence (in orchards and vineyards)

overcrops may have an additional value
when used to augment a fertilizer program

that usually no greater benefits are de-
rived from a given quantity of fertilizing
elements— nitrogen, phosphorus, and po-
tassium—applied in the form of manure
than from equivalent amounts applied in
mineral fertilizers. In some soils, how-
ever, a liberal addition of organic matter
may favorably affect soil structure in the
surface layer and so improve water pene-
tration. The roots of covercrop plants,
on decaying, leave channels in the soil
that also admit water. Covercrops grow-
ing during the dormant season of the
vines use the available nitrates and thus
may prevent leaching of the soluble ni-

trogen out of the soil. Although the im-
portance of increasing the organic matter
in arid soil has probably been over-
stressed, covercrops do have value, even
on level lands not subject to erosion.

Leguminous covercrops may actually
add nitrogen to the soil. The nitrogen is
obtained from the air and fixed in chemi-
cal combination by certain bacteria grow-
ing in nodules on the roots of leguminous

[35

plants. The nitrogen thus fixed constitutes
only a fraction of the nitrogen used by
the plants; the remainder, often the
greater part, comes from the soil. If the
nodule-forming bacteria are present and
if the crop is allowed to grow nearly to
maturity, the nitrogen added by a legume
covercrop may be considerable— perhaps
40 or more pounds per acre under the
most favorable conditions. When the
covercrop is allowed to grow only during
the winter and is turned under in March
or early in April, at a very succulent
stage, the accumulation of nitrogen is
likely to be very low. In experiments at
Davis, neither winter nor summer cover-
crops have increased the total nitrogen in
the soil.

In the coastal valleys of California,
enough rain usually falls in November
and early December to start grasses and
other plants growing. Mild temperatures
during the winter favor their growth, and
by spring a heavy cover of native plants
on fertile soils is obtained at no special
cost. Wherever the rainfall meets the
needs of both covercrop and vineyard, the
grower should not discourage this natural
winter cover, even on soils not subject to
erosion. On poor soils he may promote
it by making a light application of nitrog-
enous fertilizer in the fall. Where the
rainfall is scant— less than 16 inches— and
no irrigation water can be supplied, any
covercrop may prove detrimental by us-
ing up too much moisture.

In the irrigated areas of California,
rains sufficient to start a covercrop often
do not come until late December. Seed-
ing and fall irrigation are therefore
needed to get a good growth by spring.
Putting in the covercrop, including irri-
gation and seeding, usually costs $5.00
to $15.00 an acre. Often it would be wiser
to spend this money for nitrogenous fer-
tilizer. On such soils erosion is not a fac-
tor, because there is seldom a runoff from
winter rains; or, if a runoff does occur,
it carries away only negligible amounts
of soil.

Summer covercrops help
quality sometimes

In some irrigated table-grape vine-
yards, grasses and other plants are al-
lowed to grow after early or midsummer.
The fruit produced is clean— relatively
free from dust— and it sometimes ripens
earlier, colors better, and ships better
than fruit from clean-cultivated vine-
yards. The differences seem to be greatest
on shallow soils and least on deep, fertile
soils. The practice is sometimes also ob-
served in raisin- and wine-grape vine-
yards; but there the object is usually to
reduce costs rather than to improve
quality.

In nonirrigated vineyards which lack
summer rainfall, any summer-growing
plants, other than the vines, are detri-
mental; they use up water that is needed
to carry the vines through the season.

The basic needs of the
vineyard must be known

The fundamentals of irrigation are
fairly simple, but the individual needs
of different crops in different localities
vary so greatly that it is almost impos-

Irrigation ... its principle is easy but
its application is sometimes complex

sible to give any hard and fast rules for
irrigation. This is particularly true for
vineyards.

It can be said for all grape vines, how-
ever, that for sustained growth, the water
in the soil should be kept above the per-

[36

manent wilting percentage at all times.
This means that there must not only be
moisture in the soil surrounding their
roots, but that the moisture must be
readily available to the plants. When the
moisture drops below the permanent
wilting percentage— that is, there is not
enough readily available moisture sur-
rounding all of the roots— certain symp-
toms of distress begin to show in the
vines.

Under favorable conditions of soil
moisture, nutrition, temperature, and
cultural care, the seasonal growth cycle
of bearing vines is characterized by a
very rapid and succulent growth of the
shoots in spring and early summer; a
gradual slowing of shoot growth as the
berries rapidly enlarge; and a marked
reduction in rate of shoot growth during
the ripening period, with growth almost
ceasing by the time the grapes are ripe.
During and after harvest, the vines should
make but little new shoot growth; but
they should retain their leaves, which
may remain green or change to yellowish
green, or red and green, or red, accord-
ing to the variety.

An abrupt depletion of the water sup-
ply to a growing vine causes wilting of
the leaves and succulent shoots. Such
wilting occurs with vines growing in pots
or cans when the soil reaches the perma-
nent wilting percentage; sometimes it
occurs under field conditions in vines
growing on shallow soils in hot weather
when the permanent wilting percentage
is reached at about the same time in all
parts of the root zone. Wilting seldom
occurs on deep soils, because not all the
soil reaches the permanent wilting per-
centage at the same time, nor within a
very short time. As the readily available
moisture disappears from successive por-
tions of the soil, the vine adjusts itself,
by lessened shoot growth and dropping

of leaves, to the limitations imposed by
the reduced, but not altogether exhausted,
water supply.

How to recognize
lack of moisture

A restricted supply— meaning, under
vineyard conditions, that the readily
available water is exhausted from some
portions of the root zone— causes char-
acteristic symptoms which the experi-
enced vineyardist can easily recognize.
Early in the season, while the vines are
growing rapidly, a soft, yellowish-green
appearance is imparted by the rapidly
elongating shoot tips. This condition per-
sists near to the beginning of ripening
if none of the soil below cultivation depth
is depleted of its readily available water.
But if increasingly large portions of the
soil become dry, the rate of growth dimin-
ishes, and the appearance gradually
changes from the soft, yellowish green
of the growing tips to the harder, darker,
or grayish green of the mature leaves.
This change in appearance seems to be
caused altogether by a shortening of the
growing tips. When most of the soil be-
comes depleted of its readily available
moisture, growth ceases. Still further re-
duction in water supply causes curling of
the leaves; then, with continued further
reduction, the older leaves become desic-
cated and die, eventually dropping off.
Under these conditions of gradual de-
crease in the water supply, vines do not
wilt in the commonly accepted sense of
drooping of the leaves. An observant
grower can usually detect a water short-
age by the changed appearance of the
vines before serious injury results.

Insufficient water while the berries are
rapidly enlarging prevents them from
reaching full size; and the application
of water after the period of rapid berry
growth is past will not enable the under-

[37]

sized ones to become normal. A severe
shortage of readily available water dur-
ing the ripening period causes delayed
maturity and dull color of the fruit; often
it also causes sunburn. A slight shortage
just before and during this period may
actually hasten ripening, probably be-
cause it limits the shoot growth.

After the fruit is ripe, and especially
after the harvest, vines seem able to ad-
just themselves to a very limited water
supply. Under moderate climatic condi-
tions they will retain their leaves and
their canes will ripen, but no further shoot
growth will take place; this happens even
though the soil throughout the major por-
tion of the root zone is at the permanent
wilting percentage. In the hot desert re-
gions, however, only early-ripening va-
rieties—mostly Thompson Seedless— are
grown for table grapes. These ripen and
are harvested during June and July. Neg-
lect of such vines for the remainder of
the season often causes serious damage;
the vines must be irrigated at least once
and often several times after harvest.

How much water is needed
in various planting areas

From 16 to 54 inches of available
water, according to climate, soil, variety,
and cultural conditions, are required for
maximum crops of grapes. In the cool
parts of the coastal valleys, on soils that
will hold 12 inches or more of rainfall
as readily available water within the root
zone, no considerable benefits appear to
be derived from supplemental irrigation
if the total rainfall exceeds 16 inches. Re-
gardless of total rainfall, however, only
the water held by the soil, and available
to plants, is useful; hence, on shallow
soils, supplemental irrigation may im-
prove the growth and crops of the vines
even in cool districts with much more
than 16 inches of precipitation. On the

other hand, grapes are being grown with-
out irrigation in the Livermore Valley,
where the rainfall is about 14.6 inches an-
nually, and near Soledad in the Salinas
Valley, where it averages less than 10
inches. Vines can adjust themselves to
limited water supplies by early cessation
of growth, small crops of fruit, and drop-
ping of leaves in late summer; but they
will not yield such large crops under these
conditions as they would if additional
water were supplied.

Many of the vineyards planted on the
rolling lands bordering the coastal val-
leys of California would yield larger
crops if additional water could be sup-
plied. Vineyards on the deep, fertile,
coastal valley soils, for which cheap water
might be available, do not generally re-
spond to supplemental irrigation, for
such soils hold enough readily available
water to supply the vines throughout the
season. Some such vineyards can be and
are irrigated in seasons of abnormally
low rainfall, or in seasons lacking the
usual spring rains.

In the warmer vineyard areas of the
state, summer irrigation is practiced in
almost every place where water is avail-
able. Table 4 gives the approximate total
seasonal needs (rainfall plus supplemen-
tal irrigation) of available water for max-
imum crops of best-quality grapes. Where
the rainfall is greater than the total
amount indicated, in the table, as needed
for maximum crops, the vineyards may
or may not respond to supplemental irri-
gation ; the response depends on whether
or not the soil holds sufficient water in
the root zone to supply the needs of the
vines throughout the season. If the vines
grow vigorously until near the beginning
of the ripening period and nearly all their
leaves remain healthy until late in the fall,
little benefit is likely to be derived from
supplemental irrigation. If, on the other

[38]

Table 4

APPROXIMATE AMOUNT OF AVAILABLE WATER REQUIRED FOR MAXIMUM

PRODUCTION OF GRAPES IN VARIOUS REGIONS OF

CALIFORNIA AND ARIZONA

Region

Approximate available water required

Wine
grapes t

Raisin
grapes t

Table
grapes t

Cool areas : the cooler parts of the north coastal valleys
and rolling lands (region 1) ; heat summation less than
2,500 degree-dayst

Moderately cool areas: the middle parts of the north
coastal valleys (region 2) ; heat summation 2,501 to
3,000 degree-days

Moderately warm areas: the warm parts of the coastal
valleys (region 3) ; heat summation 3,001 to 3,500
degree-days

Warm areas: southern California valleys except the
deserts; middle and lower Sacramento Valley; lower
San Joaquin Valley ; and the intermediate central val-
ley area between the Sacramento and San Joaquin
(region 4) ; heat summation 3,501 to 4,000 degree-days

Hot areas : middle and upper San Joaquin Valley, upper
Sacramento Valley (region 5) ; heat summation over
4,000 degree-days

Desert areas : Coachella, Imperial, Palo Verde valleys of
California ; Salt River and Yuma valleys of Arizona ....

acre-inches
per acre

16-20

16-24

20-30

24-30

30-36

acre-
per

inches
acre

acre-inches
per acre

24-30

30-42

30-36

36-42

42-54

* Acre-inches per acre, including the rainfall held in the soil of the root zone and supplemental irrigation.
Water that runs off the surface or that percolates below root depth is not included.
t Grapes classified according to intended use. not strictly on the basis of variety.
j Heat summation as degree-days above 50° F for the period April 1 to October 31.
§ Such grapes are not grown in this region.

hand, the vines cease growth by midsum-
mer and drop many leaves before mid-
September, additional water given in
early summer probably would have in-
creased both growth and crop. The esti-
mated amounts of irrigation water needed
in various regions are shown in table 4.
The minimum figure may be used for
deep loam soils that do not need more
than two applications per season; the
higher figure, for shallow or light sandy
soils that require more. Soils having a
high salt content may need more water
than the table indicates to leach the ex-
cess salt out of the root zone.

When and how to irrigate
a vineyard

During the dormant season— winter or
early spring— all portions of the root zone
should be filled to the field capacity of
the soil by rainfall or by irrigation. Gen-
erally, in regions of low rainfall, this
means applying more water than calcula-
tions show is the minimum required to
wet the soil; no soils are uniform (non-
uniformity is the rule, not the exception) ,
and sufficient water must be applied to
the unit area being irrigated to wet the
areas that require the most water or that
are the slowest to take the water. For this

[39

reason, varying quantities of water will
percolate below root depth and be lost as
drainage in local areas that offer least
resistance to the percolation. One can
determine the depth of water penetration
by using either a soil auger or a soil-
sampling tube.

In the spring, after growth starts, no
additional water is required until some
of the soil within the root zone is dried
out almost to the permanent-wilting per-
centage. The vines will not benefit more
from application made before this time,
but the grower may have to start irrigat-
ing earlier than this in order to cover the
vineyard before the last vines irrigated
become too dry. The change in the ap-
pearance of the vines, caused by a reduc-
tion in rate of growth, indicates when
considerable portions of the soil have
reached the permanent-wilting percent-
age. On deep soils, no great damage is
likely to occur within several weeks after
the symptoms of water shortage first ap-
pear; but when this stage is reached by
vines growing on very shallow soil, the
available water remaining in the soil may
be only enough to carry the vines for a
few days longer without serious injury.
Where only a small head of water is avail-
able, a long time may be needed to cover
the vineyard; and unless irrigating is
started before it is really necessary, the
vines irrigated last may already be seri-
ously injured.

Soil depth is an
important factor

In the mild climates of the coastal val-
leys, if irrigation water is available in
seasons of short rainfall, or in those lack-
ing the usual spring rains, one irrigation
that wets most of the soil sometime in
early summer or midsummer would bene-
fit vineyards on deep soils; and two such
irrigations would usually be ample for

soils 1% to 3 feet deep. Grapes should
not be grown on soils less than 1% feet
deep. Most vineyards in these coastal
areas are not regularly irrigated.

The coolest parts of the vineyard areas
in the great interior valley of California
and in southern California (region 4)
receive enough winter rainfall to wet shal-
low soils to the depth of rooting; but
deep soils are fully wet only in seasons
of abnormally heavy precipitation. The
summers are practically rainless. Irriga-
tion, therefore, is needed almost every
season. In practice, irrigation varies. The
deep sandy-loam and loam soils may be
filled to field capacity sometime during
the winter or early spring and need no
applications during the summer. This
method gives good results only on the
best soils— soils which will hold about 20
inches or more of available water in the
root zone. Other soils require summer ir-
rigation: some of moderate depth and
texture need it only once in early sum-
mer; others, more sandy or shallow, need
it then and also in midsummer; and still
others being very shallow, are irrigated
regularly at 2- or 3-week intervals from
late spring until the grapes are ripe. With
these last soils, furrows or basins are
placed in the vineyard in late May to be
used the rest of the season; no cultivating
is done thereafter.

The central and northern part of the
Sacramento Valley are hot; but, since
they receive enough rain in most seasons
to wet the soil fully, they usually do not
need irrigation in winter or early spring.
Summer irrigation is essential for best
results; the number of applications de-
pends on soil conditions. A few vineyards
are unirrigated.

The San Joaquin Valley receives less
rain— about 11 inches at Modesto, 10 at
Madera, 9 at Fresno, and 6 at Bakersfield.
In general, rainfall increases slightly to

[40

the east of the axis of the valley and de-
creases to the west. Summer temperatures
are high. Practically all the vineyards
of the valley are irrigated. Winter or early
spring irrigation is common practice in
the driest areas. The number of late
spring and summer irrigations varies
from 1 to 10; the main influences are soil
conditions and the kind of grapes grown,
but water is needed somewhat oftener
toward the upper (southern) end of the
valley. Vineyards of early table grapes
on very sandy soils in the hottest areas
are irrigated after the harvest, but the
practice is not general.

Watch the vines
for signs of drought

The interval between irrigations is
shorter for table grapes than for raisin
and wine grapes. Many of the former are
on shallow soils (Madera, Exeter, and
San Joaquin series) , from which water is
removed at about the same relative rate
throughout the root zone. Because of the
very limited reserve of readily available
water after a part of such soil reaches the
permanent-wilting percentage, and the
serious consequences of total depletion
before the fruit is ripe, it is good vineyard
practice to irrigate before the vines really
need moisture; otherwise some will al-
most certainly suffer before all can be
watered. Until near the beginning of the
fruit-ripening period, table grapes even
on deep soils are usually irrigated before
much of the soil reaches the permanent-
wilting percentage; most growers figure
that the risk of injury from becoming too
dry is greater than the cost of the more
frequent irrigations. During the ripening
period, most vineyardists who have deep
soil do not irrigate at all, or wet only a
part of the soil if water is required.

Raisin- and wine-grape vineyards are,
in general, irrigated when the vines indi-

cate, by a slight characteristic change in
appearance, that the readily available
water has been depleted from a portion
of the root zone. Irrigation ceases some-
time before or soon after fruit ripening.

The quantity of water applied at
each irrigation varies between wide limits
according to the dryness, depth, and
water-holding capacity of the soil. Until
near the beginning of fruit ripening, most
growers aim to apply enough water to
re-wet completely the soil of the entire
root zone. Each grower must determine
for himself the quantity needed. A probe
(iron rod with a handle) or a soil auger
is the only equipment needed. In soils of
uniform texture, a probe usually can be
pushed into saturated soil to a depth of
5 or 6 feet, if the water has penetrated
that far. After the soil drains, however,
an auger is usually needed. The maximum
amount of water on any given soil will,
of course, be required when the soil is
driest; the amount needed for re- wetting
is reduced if the soil is less dry. At each
application, one should make regular and
extensive use of the probe or the auger
to learn how deep the water has pene-
trated; and various sections of the vine-
yard should be tested because the rate of
penetration will vary with the soil. No
general rule for the amount of water re-
quired to wet a soil can be given. Some
soils will hold less than 1 inch of water
per foot (in depth) of soil; others more
than 2 inches.

Vineyards may be irrigated by fur-
rows, basins, or checks. The furrow sys-
tem, which requires the least labor, is the
most common. The basin system, although
it distributes the water most uniformly,
requires more labor and is usually im-
practical in a trellised vineyard. The
check system is applicable only to sandy
soils where large heads of water are avail-
able.

[41]

itrogen is the best . . . perhaps the
only fertilizer needed in most vineyards

Of the three common fertilizer elements-
nitrogen, phosphorus, and potassium-
vines usually respond only to nitrogen.
Economically favorable responses to
phosphorus and potash are very rare
in California. Vines respond favorably
to nitrogen when a lack of that element is
limiting their growth and productivity—
a condition that can be determined only
by trial applications. Test plots of 100
vines, or more, to which nitrogen is ap-

plied, alongside of check plots on which
none is used, are the best means of deter-
mining whether or not the vines will re-
spond. For test purposes, 40 to 80 pounds
of nitrogen per acre (200 to 400 pounds
of sulfate of ammonia, or its equiva-
lent) is recommended. Manures and win-
ery pomace, if available at low cost, are
good fertilizers. Application of 10 to 20
tons of these materials per acre is recom-
mended if tests show a need for nitrogen.

ropagation of grapevines takes time, pa-
tience, and a considerable amount of skill

Grapevines are propagated commer-
cially in California only by cuttings,
buds, or grafts.

Since all of the good fruiting varieties
are susceptible to either nematodes or
phylloxera (pests that live in the soil in
many areas of the state) or both, they
must be grafted onto rootstocks the fruit
of which is worthless, but which resist
the attacks of these soil-borne pests. (See
pages 63 and 64 for a discussion of nema-
todes and phylloxera).

How to propagate
from cuttings

For grape cuttings, sections of canes
(matured current season's growth) are
always used. These should be taken from
healthy, vigorous vines of the proper va-
riety—preferably mature vines that have
grown well, borne moderate crops, re-
mained free from disease, and have not
been injured by pinching, topping, or by
autumn frosts.

Grape cuttings should be made while
the vines are dormant. They must be
made promptly after the brush is pruned

off the vines, since two or three warm,
rainless, windy days may dry the brush
to such an extent that cuttings from it
will not grow.

For canes from which to make cuttings,
well-nourished, well-matured, current sea-
son's wood growth from any part of the
vine is suitable. Cuttings % to % inch
in diameter and 14 to 18 inches long are
commonly used. Seldom, if ever, should
cuttings of the fruiting varieties be less
than Y± inch in diameter at the small end ;
a length of 14 inches is adequate. The
resistant-rootstock varieties produce
canes of smaller diameter than those of
the fruiting kinds. Wood of normal size
should be used. If the resistant cuttings
are to be rooted, then planted in the vine-
yard, and finally budded, they should be
longer than cuttings of the fruiting vari-
eties— 16 to 18 inches from the top bud
to the base of the cutting.

The cut at the base of the cuttings is
usually made straight across, just below
a bud or node. The top cut is made at
an angle of about 45° at a distance of %
to 1% inches above the top bud (see

[42]

photo). The angles and position of top
and bottom cuts made in this manner will
easily differentiate the top and bottom
of the cutting in future handling opera-
tions. In addition the sloping cut, re-
moved % inch or more from the top bud,
avoids any cracking of the wood in the
node, which might allow the top to dry
out and thus injure the bud.

Cuttings should be planted in a well-
drained soil as soon as possible after they
are made. The nursery row is usually the
best storage place. If, however, they can-
not be planted immediately, because of
wet soil or other difficulties, they should
be stored in a cool place, preferably in
moist sand. For handling and storage,
cuttings are conveniently tied into bun-
dles of one or two hundred each.

The soil for the nursery should be fer-
tile, preferably a sandy loam, with irriga-
tion available. Even in the north coast
region, where vineyards are grown with-
out irrigation, it is impractical to grow
a nursery without irrigation. The cuttings
are planted usually to the depth of the
second bud from the top of the cutting,
and are completely covered with a ridge
of loose soil. Though the procedure will
vary with the scale of operations and the
equipment available, any method of
planting is suitable that places the cut-
tings at the proper depth in a straight
row, with the soil around them firmly
settled. If they are put in a trench, one
must pack the soil firmly around the base
of the cuttings by tramping as the trench
is filled or by irrigation. If the cuttings
are stuck in the cut made by a subsoiler,
one must settle the soil around them by
irrigation while planting. In a fertile soil
in a hot region, the cuttings may be
placed as close as 2 inches apart in the
row with the rows 4 feet apart. In a less
fertile soil or in a cooler region, 3- or

These are cuttings of Emperor vines, showing
the type of wood that should be used. Cuttings
are about 14 or 15 inches long— slanted at top.

[43]

-Nsl

* wm

Steps in budding. Left to right: bud removed from the bud stick; notch made in stock to re-
ceive the bud; the bud in place; the finished product, tied, and ready to be covered with soil (see
below).

4-inch spacing in the row will produce
larger and better rootings.

During the summer the nursery should
be carefully tended so that the vines will
grow vigorously and be well matured be-
fore autumn frost occurs. This aim is
usually best accomplished by irrigating
rather often in the spring and early sum-
mer, less frequently in late summer, and
not at all in the last 6 or 8 weeks of ex-
pected growth. The ridges of soil over
the tops should be left until the cuttings
have rooted and made appreciable top
growth. Then one may remove the ridges
to discourage the formation of surface
roots.

The rootings may be dug any time after
the leaves fall. They should be sorted ac-
cording to size into at least two grades,
and bound into bundles of 25 or 50 each
for convenience in handling. Until used
they should be stored by heeling-in in
moist sand or soil in a cool location.
Where weather conditions permit, it is
good practice to move the rootings di-
rectly from the nursery to the vineyard for
planting. Rootings that have made less
than 6 inches of well-matured top growth

or that do not have at least one good root
Ys inch in diameter from the basal node
of the cutting, should not be planted in
the vineyard.

How to propagate
by budding

Stock rootings of resistant varieties
that are to be budded or grafted should
be made "sucker proof" by removal of
all eyes or buds from the below-ground
portion before planting. This can be done
most economically before the cuttings are
planted in the nursery. The rootings
should be planted with 4 or 5 inches of
their main body above the surface of the
ground so that the bud or graft can be
put in aboveground; scion roots are thus
avoided. Budding is done as early in the
autumn as matured buds of the desired
fruiting variety can be obtained— usually
in August or September. The bark of the
cane from which buds are taken must be
light brown, since many buds from green
canes or green parts of canes will not
grow. As soon as the canes (bud sticks)
are taken from the parent vine, the leaves
are removed ; and the bud sticks are kept

[44]

fresh by being wrapped in moist burlap
or packed in wet moss or other suitable
material.

A special form of chip bud (see photo)
is commonly employed. To remove a
bud from the cane, two cuts are neces-
sary. The first is made deep into the bud
stick, beginning just below the bud and
sloping downward at an angle of about
45°. The second cut is started about % or
V2 inch above the bud; and the knife,
traveling in a nearly straight plane be-
hind the bud, ends at the surface of the
first cut, removing a wedge-shaped chip
Vs to %6 inch thick at the lower end and
a little more than % inch long. Some
workmen reverse the order in which the
cuts are made. The wood in the chip is
not removed from the bud.

A notch into which the bud will fit well
is made in the stock above the ground
level, preferably on the side of the vine
from which most of the top growth arises.
The work is easier if one first removes
the soil around the vine to a depth of
1 to 2 inches. The angle made by the two
cut surfaces of the notch in the stock
should be slightly more acute than the
angle formed by the cut surfaces of the
bud piece. This technique insures inti-
mate contact between the lower end of
the bud piece and the corresponding cut
surface of the stock. The bud chip must
be so inserted into the notch that a good
fit is obtained. It is then securely tied in
place with budding rubber beginning the
tie at the thin end of the chip.

Immediately after being tied, the bud
is covered with moist, well-pulverized
soil; and this, in turn, is covered with
4 to 8 inches of well-pulverized soil. If
the soil is fairly moist, a covering 4 inches
deep may be adequate. If the soil is dry,
an 8-inch covering is better. In very dry
soil it is well to cut off one fourth to one
half of the tops of the vines at the time

of budding. The bud is callused-in— that
is, it grows fast to the stock— within 4
weeks. It usually remains dormant, how-
ever, until the following spring.

Avoid damaging the
budded vines

During the winter, field-budded vines
need no attention, provided the staking
or trellising has already been done. Be-
cause of the danger of damaging the buds
in driving the stakes, it is best to stake
the vineyard before planting. The follow-
ing spring, when the buds on the root-
stock vines are swollen and nearly ready
to break, the scion buds should be un-
covered. The usual procedure is then as
follows: Cut the rubber used for tying.
On each vine, carefully examine the scion
bud to ascertain that it is alive and grown
fast to the stock; do not hesitate to apply
considerable pressure to the bud chip,
for if the union is good, the chip can
hardly be dislodged by one's fingers. If
the scion bud appears well united with
the stock and is beginning to grow, cut
off the stock 1 or 1% inches above the
bud. Place a building-paper sleeve about
1% or 2 inches in diameter and about
9 inches long over the end of the stock
and the scion bud, banking 3 or 4 inches
of loose soil around the lower end of the
sleeve to prevent the wind from blowing
it away. Suitable sleeves may be made by
rolling 9-inch squares of waterproof
building paper in the form of tubes. This
practice protects the buds and scion
shoots from damage by wind, cutworms,
rabbits, and drifting soil. The sleeves also
force the scion shoots to grow upright,
and thus facilitate training. As soon as
the scion shoot grows up through the
sleeve, tie it to the stake. Remove all stock
suckers and scion roots whenever they
appear. If the scion bud is not good, the
vine may be rebudded or grafted imme-

[45]

diateiy or the top may be pruned back
to one or two buds and then rebudded
the next fall. When the vines are large,
grafting is preferred; but when they are
small it is best to rebud immediately or
the next fall.

Often stocks are killed by being cut
off when the scion buds are imperfect.
Unless one is experienced it is not easy
to find all the poor unions. Rootstock
rootings properly disbudded before plant-
ing grow only from the top or from the
scion bud; hence, if the top is cut off and
the scion bud fails to grow, the vine must
be rebudded or grafted then or it is lost.
To avoid this danger one may proceed as
follows:

About the time the rootstock buds are
ready to break, uncover the vines to ex-
pose the scion buds. Prune all the canes
on each rootstock back to base buds.
Cover the scion bud lightly (an inch)
with loose soil, or place over it a build-
ing-paper sleeve. Watch the vines closely,
going over the vineyard about once a
week. As the scion buds start, cut off the
tops of the rootstocks an inch or more
above them. As the scion shoots grow,
tie them carefully to the stake as in train-
ing any other vines. Thereafter keep the
soil away from the base of the scion shoots

to discourage scion roots, take off all
stock suckers that start from the root-
stocks, and remove the rubbers after the
lower parts of the scion shoots have hard-
ened (May or early June ) .

Each time, in going over the vineyard,
remove all shoots from the stocks on
which the scion buds have not started.
Sometime in May, uncover the remain-
ing scion buds that have not started and
are thought to be defective, cut the rub-
bers, and examine the buds. Thereafter,
allow the shoots to grow on all stocks that
have defective scion buds. Rebud these
next fall.

To regraft budded vines whose buds
have not grown, or to correct plantings
of mixed varieties, or to change the va-
riety in an entire vineyard, the grafts
commonly employed are whip, cleft, or
notch.

How to make grafts
onto resistant stock

Whip grafting. For vines less than
% inch in diameter the long whip graft
is perhaps best.

The sloping cuts are made at an angle
of 15° to 25° with the side of the stock
or scion and must be the same length on
both stock and scion. The tongue cut is

A long whip graft. Left to right: the sloping cuts made on both stock and scion; the tongues cut
and opened out; the completed graft, tied and ready for covering with moist, pulverized soil.

started about one third of the distance
from the point and it ends at about two
thirds of the distance from the point to
the base of the cut. Opening out the ton-
gues by bending them over with the knife
as it is withdrawn aids in putting the
scion on the stock. The parts are pushed
together, tongues interlocking, until the
cut surfaces coincide as completely as
possible. If the stock and scion are of
the same diameter, a good fit can be ob-
tained all around. If one is larger than
the other, one side must be fitted so that
the line between the bark and the wood—
the cambium or region of growth— of the
scion coincides with the corresponding
line on the stock as completely as pos-
sible on that side. This line is the position
of the cambium layer. The graft is then
tied very firmly with budding rubber,
raffia, or string. If rubber is used, it must
be cut and removed after the graft has
firmly grown together.

Cleft grafting. Vines % to 2 inches
in diameter are cleft-grafted most easily.
The vine is sawed off so that about 2
inches of smooth, straight grain is left at
the top of the stump. If one saws at, or
too near, a place where the grain of the
wood is crooked or curly, great difficulty
will be experienced in obtaining a good fit.

Vines of fruiting varieties, grafted
merely to change the variety, are usually

mimm

Dotted line shows where trunk should be cut
off for grafting. The bark should not be re-
moved as completely as shown— cambium must
be preserved.

sawed off 2 to 4 inches below the ground
level. When resistant stocks, however, are
grafted to a fruiting variety the graft
must be put in above the level of the
ground; if the grafting is done below
ground, scion roots will form, and the
resistant stock may die. Resistant stocks
are therefore cut off just above ground
level.

The vine is cut off at the level where
the scion is to be inserted. The stump
is split to a depth of 1 or 1% inches

The steps to be taken in cleft grafting. Left to right: making the notch; prying sides apart; placing
the scion on the stock so that the cambiums match. A grafting tool as shown will come in handy.

[47]

The steps in notch grafting (see text). Any type of graft must be securely tied or sometimes nailed
in place, to be held securely until a union is formed and the graft begins to grow again.

with the broad edge of a special grafting
tool; a carpenter's chisel may be used
instead but is less convenient. After split-
ting the stump, the grafting tool is re-
moved; and the small end is placed in
the cleft to pry it apart for insertion of
the scion.

The scion is cut in wedge form, a little
thicker on the side that is to be placed
nearest the bark of the stock. The length
of the wedge depends on the character
and size of the cleft in the stock. The
wedge— usually with a long taper— is in-
serted so that the cambium of the scion

Finished graft should be covered with soil to
upper dotted line. Too shallow covering will
tend to dry out and spoil the graft union.

coincides with the cambium of the stock.
As the bark is thicker on the stock than
on the scion, the outer surface of the scion
will be set in slightly from that of the
stock. Although the cambiums of the stock
and scion will seldom correspond exactly,
a satisfactory union is obtained if they
are very near together or cross in one
or two places. Most grafters put the scions
in at a slight angle— in at the bottom and
out at the top.

The scion should be cut with a sharp
knife and immediately inserted in the
stock before it dries even on the surface.
Scions of two buds are generally used.

If the vines are an inch or less in diam-
eter, one scion to each vine is sufficient.
For larger vines, two scions are prefer-
able whenever both can be made to fit
securely. If both of them grow, the weaker
is removed as soon as the other is tied
to the support.

To hold the scions firmly in place,
vines less than 1% inches in diameter
should usually be tied with a few tight
wrappings of raffia, string, or budding
rubber around the top of the stump.
Larger vines need not be tied. Any rub-
ber used for tying should be removed
after the grafts are firmly grown together.

Notch grafting. The notch graft dif-
fers from the cleft graft in the shape of
the scion and the method of insertion.
Instead of being wedge-shaped and in-
serted in a cleft or split, the scions are

[48]

shaped to fit into a V-shaped notch on
the side of the stock extending from the
top of the stump downward for 1 to l 1 /?
inches. The width and the depth at the
top of the notch should be about the same
as the diameter of the scion to be used.
The notch tapers to a point at the bot-
tom. The scion should be fitted into it so
that the cambium layers of scion and
stock coincide as completely as possible.

One can form the notch in the stock
most conveniently by first making a saw
cut as long and as deep as the notch is to
be. Then, with a sharp knife, the notch
is widened at the top and tapered to a
point at the lower end (see drawings).
When finished, the cut surface should
be smooth and straight, for if it is rough
and irregular, a good fit with the scion
cannot be secured. The angle formed at
the bottom of the notch by the cut sur-
faces should be 70 to 90°.

The scion should be so shaped that
when it is placed in the notch, the cam-
biums of the stock and scion fit together.
The angle that the cuts of the scion make
with one another should be slightly more
obtuse than the angle of the notch. Thus,
when the scion is placed on the stock, the
contact will be firm at the line of the
bark, insuring close contact of the cam-
bium layers.

After insertion in the notch the scion
should be held firmly in place until the
tissues grow together. This is accom-
plished most easily by driving in one or
two 1-inch, 19-gauge, flat-headed wire
nails.

Covering the graft. As soon as any
graft is finished the stake should be
driven close to the vine, unless a stake is
already there. The graft is then carefully
covered at once with a wide mound of
moist, well-pulverized soil. No wax and
no covering other than moist soil need
be used. The soil immediately around the

scion should be put in place very care-
fully so that the position of scions is
not disturbed. The scions are completely
covered. If the weather is cool and moist
and likely to remain so until the scions
grow, merely covering them to their tips
is sufficient. In the hot, dry weather of
the interior valleys, however, scions
should be covered to a depth of 2 or 3
inches so that they cannot become even
slightly dry. When finished, each graft
will be in the middle of a wide mound
of soil; narrow mounds may not remain
moist enough to insure growth.

The mounds must not be disturbed by
hoe or cultivator until the unions are well
formed. If the scions are completely cov-
ered and the mounds form a hard crust,
this crust should be carefully broken.

Suckering. Many large, vigorous
shoots may come up from the stock.
When the grafts have started to grow
vigorously, so that the shoots can be tied
to the stake, it is safe to begin suckering.
At this time the workman can sometimes
pull up the suckers by hand without re-
moving any soil. Unless he is certain,
however, that they are not entangled with
the scion, he must carefully remove some
soil and ascertain how to detach them
without disturbing the union.

If grafts are slow in starting and if the
suckers are vigorous, one must sucker
before the scion has grown much. One
can do this safely only by using extreme
care.

Training. When the union is complete,
the growth of the grafts on large vines
is generally rapid— often an inch a day;
many canes grow 15 feet or more by the
end of the season. Unless this vigorous
growth is properly managed, its benefits
are lost, and it causes great trouble the
following year. The shoots are managed
exactly the same as in training excep-
tionally vigorous, ungrafted vines.

[49]

arvesting . • . the market determines a
number of the picking methods to be used

Most table grapes are
shipped east to market

Most of California's table grapes are
marketed 2,000 miles or more from the
vineyards. Transportation is principally
in refrigerated railway cars or trucks.
The time in transit is 7 to 11 days or
more. The temperatures in the refriger-
ated cars after the fruit is cooled usually
average about 45° F. To market grapes
successfully under these conditions re-
quires care and skill in harvesting and
packing to insure that the fruit leaves the
shipping point in the best possible con-
dition.

Grapes marketed within the state are
not subjected to such a long journey. Va-
rieties of somewhat poorer carrying
qualities but of better eating quality, such
as the Muscat, can therefore be placed
on the local markets.

When to pick. In determining the
best time or stage of development for
picking table grapes, the chief considera-
tions are: (1) They should be attractive
to the consumer in appearance and in
eating quality; (2) they should keep and
carry well; and (3) they should, if pos-
sible, reach the market while they will
bring relatively high prices.

Ripening, as it interests the grower,
consists largely in an increase in sugar,
a decrease in acidity, and the develop-
ment of characteristic color, texture, and
flavor. These changes are continuous as
long as the grapes remain on the vine, but
practically cease after picking. Under
normal conditions there is a gradual im-
provement until the best stage is reached
for the purpose to which the grapes will
be put, then a gradual deterioration takes
place.

Early in the season there is a tendency
to market unripe fruit, which, though
often sold for a high price, disappoints
the consumer reduces sales, and depresses
the market. The fact is recognized in the
fruit and vegetable standardization laws
of California, enacted to promote the in-
dustry by preventing, as far as possible,
the shipment of inedible fruit, together
with fraudulent practices in packing and
selling.

How to measure maturity. Of the
changes involved in the ripening of
grapes, only the content of sugar and acid
can be measured accurately and conven-
iently. In a few instances color definitions
can be given.

For practical purposes, the sugar con-
tent of ripe grapes is measured accurately
enough with a hydrometer (saccharim-
eter). These instruments are generally
calibrated in the Balling or Brix scale and
read directly in per cent sugar by weight.
The hydrometer measures specific gravity
(weight per unit volume as compared
with that of pure water) . In ripe grapes,
sugar is the chief substance affecting
specific gravity. In comparison with
sugar, other dissolved substances have a
small effect; hence one may estimate the
quantity of sugar present by measuring
the specific gravity.

Hydrometer sugar test. For the
sugar test a representative sample, 2 or
3 pounds or more, of the grapes to be
tested is chosen. The grapes are thor-
oughly mashed in a pan or a pail with
the hands or with a wooden masher or
by being passed through a juice extrac-
tor. To press the juice from the pulp in
hand crushing a square of cheesecloth
is placed over a pan or a pail and the pulp

poured upon it. A bag is formed of the
cheesecloth by gathering together the
edges; the bag is gently pressed with the
hands until sufficient juice is extracted.
The extracted juice is poured into the
cylinder to be used with the hydrometer.
The cylinder should be filled to overflow-
ing to get rid of the foam that forms, as
the juice is poured into the cylinder. The
hydrometer, which should be clean and
dry, is then inserted into the juice until
it comes to rest of its own accord. The
hydrometer is read at the general level
of the liquid and not at the top of the
meniscus (curvature of the surface) . The
temperature of the juice is carefully
taken, and the temperature of calibration
shown on the hydrometer is observed.
If the temperature of the juice is higher
than the calibration temperature shown
on the hydrometer, 0.33° Balling (or
Brix) for each degree Fahrenheit differ-
ence in temperature (0.06 for each de-
gree centigrade) is to be added; but if
it is lower, the correction is subtracted.
The result— the corrected or true read-
ing—is the approximate percentage of
sugar.

Acid titration. Use a pipette to meas-
ure 10 cubic centimeters of the clear juice
into a flask of convenient size. Fifty to
100 cc water and 3 drops of phenol-
phthalein indicator solution are added.
A standardized solution of sodium hy-
droxide (0.133 normal) is slowly run
from a burette into the flask containing
the diluted juice, with a constant stirring
or shaking of the flask, until a faint pink
color is obtained that lasts 10 seconds or
more. A solution standardized to 0.133
normal is equivalent to 0.01 gram tar-

The hydrometer sugar test. Top: crushing the
grapes into cheesecloth to obtain juice. Bottom:
hydrometer floating in a cylinder of juice is read
in a manner similar to a thermometer.

■ ■■■■ ~i:::^--;vC-V'.-:»«' : ; :i ; ;:

taric acid per cubic centimeter.* The re-
sult is expressed in grams tartaric acid
per 100 cc of juice. If the procedure is
carried out as prescribed, the number of
cubic centimeters of the sodium hydrox-
ide solution used, divided by 10, equals
the tartaric acid in the juice in grams
per 100 cc.

Balling-acid ratio. The Balling hy-
drometer reading divided by the acidity,
in grams per 100 cc,f gives the Balling-
acid ratio— a better measurement of the
palatability of table grapes than either
the sugar content or the acidity alone.
The minimum desirable Balling-acid ratio
varies with different varieties. The
Thompson Seedless, Malaga, and Ribier
should be about 25 to 1— that is, 25 parts
sugar to 1 part acid; the Ohanez, Cor-
nichon, Muscat, and Emperor 30 to 1;
the Tokay, Olivette blanche, and Red
Malaga 35 to 1. All of the varieties except
Ribier, Red Malaga, and Emperor should,
in addition, have a Balling of 17° or
higher; these varieties should be at least
16° Balling.

Climatic conditions affect the relative
amounts of sugar and acid, and their in-
fluence is reflected in the Balling-acid
ratio: If the weather is very hot during
the ripening period, the Balling-acid ratio
will be high, and the grapes palatable at
relatively low sugar. If the weather is
cool, the acid will be higher, and more
sugar will be required for equal palata-
bility.

* The tartaric acid equivalent of ordinary 0.10
normal sodium hydroxide is 0.0075 gram tartaric
acid per cubic centimeter.

f Sometimes per cent acid, grams acid per
100 grams solution, is used in this calculation.
Grams acid per 100 cc is preferred because it is
easier to obtain.

Acid titration test. Top: measuring out juice
with a pipette. Center: measuring the phenol-
phthalein solution with a medicine dropper.
Bottom: adding the sodium hydroxide solution
from a burette and noting pink coloring.

Judging maturity in picking. Ob-
viously the picker cannot test each cluster
for sugar and acid. In judging maturity
he relies chiefly upon the following indi-
cations: (1) Color and condition of the
stem; if the main part of the stem that
attaches the cluster to the cane is brown
and woody, or if the stem framework of
the cluster is of light straw or yellow
color, the grapes are likely to be mature
for table use. (2) Taste of the berries;
the greenest grapes of a cluster— those
near the apex— should be the ones chosen
for tasting. Since the sense of taste is
quickly dulled by frequent use, the picker
must rely principally on other character-
istics, using taste to correlate maturity
with the color of the fruit or the condi-
tion of the stems, and then only occa-
sionally when he cannot otherwise decide
whether or not to pick a given cluster.
(3) Appearance of the berries; red or
black grapes develop their characteristic
color as they ripen. Though a well-colored
grape is not necessarily ripe, when grown
under the same conditions the best-
colored grapes are usually the ripest.
Green or white varieties become more
nearly yellow or white as they ripen.

Not all the fruit in a vineyard nor
even on the same vine ripens at the same
time. Usually one must go over the vines
2 or more times in order to harvest most
of the table grapes at the proper stage.

Wine grapes are sent
directly to the winery

The time for picking wine grapes de-
pends to a considerable extent upon the
kind of wine to be made. Grapes for dry
wines should be of high acidity and mod-
erate sugar content. Such grapes, there-
fore, are usually harvested after they test
20° Balling but before they reach 24°.
For sweet wines the grapes should be
high in sugar and moderately low in acid.

Grapes for sweet wines may attain as
high a sugar content as possible without
raisining— this is usually 24° Balling or
more.

For ordinary wines, all the crop is har-
vested at a single picking. This is the
usual practice in California. For fine
wines, one may make several pickings in
order to get the fruit uniform and all at
the best possible stage of maturity. Even
when the crop is all harvested at a single
picking the clusters that have waterberry
or redberry— soft, flabby berries— those
that are very green, and especially those
that are badly raisined, decayed, or moldy
should be separated from the good fruit,
since they may spoil a good lot of wine.

The grapes are usually picked into field
lug boxes and hauled in them, or in bulk
loads, to the winery. The best practice,
of course, is to crush the fruit and put
it into the fermentation vats as soon as
possible. If for any reason the grapes
must be hauled a considerable distance
or held for more than a few hours before
crushing, then they should be picked and
handled carefully. Broken and crushed
grapes spoil quickly, and the organisms
that develop in the spoiled grapes may
give the wine a bad odor and a high
volatile-acid content. Dirty, juice-soaked
boxes are objectionable; and bulk haul-
ing for long distances is undesirable.

Raisin grapes must be
fully ripe before picking

Grapes are usually considered ripe for
raisins at 23° Balling or more. With the
natural sun-drying process, the riper
the grapes the better the raisins and the
higher the yield, so long as there is no
damage from rain; hence, although
grapes harvested at 23° Balling make
good raisins, those allowed to attain 24°
or 25° will be even better. The degree
of maturity at which to pick is usually a

[53]

compromise between two considerations:
first, the better quality and heavier yield
obtained if full ripening takes place;
second, the risk of unfavorable drying
conditions if the grapes are allowed to
hang on the vine too long. The earlier
they can be harvested, the greater are
the chances of their drying without inter-
ference from early fall rains. In the San
Joaquin Valley the grapes are usually al-
lowed to attain a minimum of 23° Ball-
ing, provided this occurs by the first of
September. Most of them should be

picked by the middle of September re-
gardless of the sugar content.

With grapes that will be dehydrated,
weather conditions are only a minor fac-
tor in the drying; further, the influence
of maturity on the quality of the raisins
is less marked than with the natural sun-
dried product. Even for dehydrated rais-
ins, however, the grapes should be at
least 21° Balling— preferably, between
23° and 26°. Harvesting must be com-
pleted before the early rains cause dete-
rioration of quality.

ticking and shipping must be done with
speed to avoid any unnecessary spoilage

The containers and the methods of pack-
ing used for grapes to be shipped to
eastern markets have been fairly well
standardized. Throughout harvesting and
packing, efforts are directed toward mov-
ing the fruit as rapidly as possible from
the vines to the refrigerated cars to reduce
deterioration to a minimum.

Containers are fairly
well standardized

Most of the California table-grape crop
is marketed in the so-called "display"
grape lug and recent variations of it. The
display lug is 5% x 13% x 16% inches
(inside) , with its total depth (5% inches)
made up in two parts— the lower part 4%
inches; the upper part 1% inches. The
lid is nailed on the box with no cleats
other than the 1%-inch top section. When
one attempts to remove the lid, the entire
top part comes off, leaving the box 4%
inches deep. The box is filled as com-
pactly as possible without damaging the
fruit. Though the grapes settle during
transit, the removal of the top 1%-inch
section with the lid leaves the remainder
of the box completely filled and therefore
suitable for display.

Baskets, crates, or lug boxes of other
dimensions and also sawdust lugs are oc-
casionally used in the domestic markets.
Sawdust chests measuring 7% x 14 1 % 6 x
18% inches (inside) are used for export.

For wine grapes shipped fresh to east-
ern markets the most common lug is 5% $
x 13% x 16% inches (inside) . When lids
are placed on these wine-grape lugs, a
cleat 1x /\q inch square is used on each end
beneath the lid.

Grapes are packed
according to use

Table grapes in lugs are usually
packed by the "stems up" method. To
make this pack, the box is tilted by plac-
ing one end of it crosswise in another box
or by placing it on a special stand. Pack-
ing may start by laying one or more clus-
ters horizontally in the low end of the box.
Filling continues from this end, with all
clusters placed nearly upright except
those needed to make the bottom of the
pack solid. The fruit is occasionally
pressed toward the low end as the box is
being filled, so that when finished the
pack is firm.

[54

To pack a sawdust chest, a strip of
paper of suitable width is placed cross-
wise in the box, with the ends of the paper
projecting a few inches above the sides
of the box. Then the proper quantity of
grapes (usually 32 pounds) is placed in
the lined container, stems up or other-
wise. Sawdust is shaken into and between
the clusters by placing the box on a
special vibrator (made for that purpose)
while the sawdust is being run into the
box from an overhead bin. Only specially
prepared grape-packing sawdust is suit-
able for packing grapes. If the shaking
is to be done by hand, % to ^2 inch of
the special sawdust is placed in the bot-
tom of the box. Then is added a layer of
grapes, consisting of about half the total
amount that must go into the container.
The layer of grapes is covered with saw-
dust, and the lug is rocked by alternately
raising and lowering the ends about an
inch, each time allowing the raised end
to drop to the bench. This causes the saw-
dust to settle in among the grapes. Next,
the remainder of the grapes are placed
in the box as a second layer, into which
more sawdust is shaken. Before the lid is
nailed in place the projecting ends of the
paper lining are laid over the top of the
finished pack.

Wine grapes are usually "jumble-
packed," the clusters being fitted into the
box in the best way possible, but with no
regular order of arrangement.

Field packing
takes less time

Grapes are packed either in the vine-
yard or in special sheds or houses. Both
methods have their merits. Field packing
involves least handling and also least de-
lay in getting the grapes into a refriger-
ated car for shipment. Given an adequate
supply of skilled labor, favorable weather,
and grapes in good condition, a shipper

is likely to find field packing the cheapest
and probably the best method. If, on the
other hand, there are not enough skilled
workmen for both picking and packing,
or if the grapes require an unusual
amount of trimming, or if the weather
conditions are unusually severe, more
uniform results may be obtained by re-
packing in a shed.

Trimming will improve
the clusters

The picker should grasp the cluster by
the stem to remove it from the vine. He
should cut the stem with a sharp knife or,
better still, with picking shears. He or
the packer (depending on where packing
is done) should carefully remove all de-
fective berries, particularly those broken
or decayed, by cutting (with shears) the
stem attaching the berries to the cluster.
Under no circumstances should the berry
be pulled off with the fingers, leaving the
wet brush attached to the cluster. The
cluster is improved by removing all the
undersized or insufficiently colored ber-
ries. Since, however, the expense usually
makes this work impractical, only the
worst of these offtype but sound berries
are generally removed. Throughout the
handling operations, extreme care should
be exercised to avoid crushing any grapes
or breaking them loose from the stems.
Any break in the skin offers an easy en-
trance for molds, yeasts, and other decay-
causing organisms.

Precooling and sulfur
dioxide treatment

The sooner the grapes are cooled after
being removed from the vine, the better
they will be when they reach the market.
They will deteriorate as much in one day
at a temperature of 85° or 90° F as in a
whole week at 45°. The rate of cooling
in the refrigerator car with only the nor-

[55]

mal circulation of air to carry away the
heat from the fruit is very slow. Usually
3 or 4 days are required to cool the grapes
to below 50° in the top layer of the car.
By the use of car precooling fans, or other
suitable precooling devices, cooling can
be accomplished in 12 to 18 hours. The
same results are obtained, but at a higher
cost, by warehouse precooling.

If grapes are exposed to sulfur dioxide
gas in the atmosphere, they will absorb
it. A concentration of 15 to 20 parts per
million of sulfur dioxide in sound table
grapes greatly reduces the rate of deteri-

oration. Ordinary wine grapes require
about 50 parts per million. Under actual
operating conditions the best methods of
application involve displacing the air in
a standard refrigerator car, or in some
other treating chamber, with sulfur di-
oxide diluted with air to a concentration
of approximately 2 per cent by volume.
The ventilators and doors are then tightly
closed, and the grapes absorb the sulfur
dioxide from the mixture of sulfur di-
oxide and air. The chief benefit of the
sulfur dioxide is its repressing effect on
molds and other organisms.

rying raisins • • • two different meth-
ods are commonly used in California

The clear, warm autumn weather of the
middle and upper San Joaquin Valley
permits raisins to be dried between the
rows of vines in the vineyards, a method
commonly known as natural sun-drying.
About 90 per cent of the raisins of the
state are dried in this manner. Most of
the remainder are dehydrated.

Sun drying is done
right in the vineyard

The grapes should be picked and then
spread directly on paper or wooden trays
(2x3 feet), from 20 to 24 pounds of
fresh grapes per tray. When the top layer
of berries has browned and shriveled

(usually about a week later), the grapes
are turned upside down onto another tray.
When the grapes are two thirds to three
fourths dried, wood trays are stacked, and
paper trays are rolled. The raisins are
allowed to continue drying in the stacks
or rolls. When they have reached the point
where juice can no longer be squeezed
out— 16 per cent moisture or less— they
are packed tightly into sweat boxes or
picks and hauled to central processing
and packing plants.

To prepare a good place for the trays,
the spaces between the rows in the vine-
yard are smoothed and leveled. Usually
with a light crop the space between two

Left: Turning raisins in the vineyard. Empty tray is placed over full one, and both trays are turned
over. Former full tray is used for next turning. Right: stacking partially dried raisins.

rows will furnish enough room in which
to dry the fruit from both, leaving the
alternate space unobstructed; but with a
heavy crop every space is needed. If the
rows in the vineyard run north and south,
one need merely level and smooth the
space; but if they run east and west, the
bed is best prepared so that it slopes to
the south and thus exposes the grapes
more directly to the sun to hasten drying.
East-west direction of rows is preferred
for rapid drying.

The three important raisin varieties-
Thompson Seedless, Muscat, and Black
Corinth— all may be dried by this method.
The Black Corinth, however, ripens very
early and, if the weather is hot, is best
dried on stacked wooden trays with little
or no direct exposure to the sun.

Dehydration takes
more machinery

In the San Joaquin Valley north of
Madera County and in the lower Sacra-
mento Valley, where temperatures are
lower, the grapes ripen later than in the
middle and upper San Joaquin, and early
fall rains are more common. In these dis-
tricts it is somewhat hazardous to dry

the raisins in the vineyard without pre-
treatment. Dehydrators are being used
to a considerable extent, producing the
golden bleached raisins. First the grapes
are dipped into a solution containing 0.2
to 0.5 per cent lye (sodium hydroxide)
at a temperature near boiling. Then they
are rinsed by spraying with cold water.
The length of the hot dip— usually 1 to 5
seconds— depends upon the strength of
lye, the temperature, and the maturity of
the fruit. The grapes are dipped until very
faint checks show in the skins after the
cool rinse. After dipping, they are spread
on trays and exposed to the fumes of
burning sulfur or sulfur dioxide gas, un-
til the green color has bleached to a yel-
lowish white. Then they are dehydrated
at 140° to 160° F. The product-a light,
brilliant, golden yellow— is very attrac-
tive. As the raisins taste strongly of sul-
fur dioxide, they are unpalatable for
eating out of hand; but when they are
used in cooking or baking, the sulfur
dioxide disappears to the extent that it is
neither noticeable nor harmful. The
golden-bleached product of California
competes in foreign markets with the Sul-
tana raisins of Australia and the light
colored raisins of Greece and Turkey.

iseases and pests must be controlled
and sometimes avoided for best results

California is free from many of the
serious fungus diseases and insect pests
that trouble the grape growing industry
elsewhere. However, a number of such
diseases and pests are present in the state,
and must be controlled, for successful
operation of a vineyard.

Powdery mildew is
controlled with sulfur

Powdery mildew is also called oidium,
in other grape-growing regions, and is

caused by a fungus that may grow on all
green parts of the vine. The disease is
discussed in detail in Extension Circular
31, which is out of print, but may be
found at many city and county libraries.
What to look for. Mildew appears
on the surface of affected parts of the
vines as a grayish white, powdery growth.
When rubbed off, weblike black, or dark-
brown discolorations remain. Mildew
causes curling and withering of young
leaves and dark staining on the surface

[57]

of older leaves; dropping, discoloration,
or splitting of the berries ; browning and
poor maturity of the canes.

It is present in every grape-growing
region of the state, and varies in serious-
ness with the season, unless it is artifi-
cially controlled.

What to do. As a preventive measure,
dust the vines with finely divided sulfur-
use of power machines for dusting is
best. However, if only a few vines need
dusting, a hand-operated duster will do
if the sulfur is so applied that it drifts
over and through the vine.

Do not dust wet vines. Do not dust when
the temperature is over 100° F.

The following schedule of dusting is
recommended for prevention of powdery
mildew :

First dusting— 5 to 7 pounds of dust-
ing sulfur per acre, when the vine shoots
are 6 to 8 inches long. This application
is essential and should be made regard-
less of the temperature conditions. It
should be repeated after heavy rains.

Second dusting— 5 to 7 pounds of
dusting sulfur per acre, when the shoots
are 12 to 15 inches long.

Third dusting— 8 to 10 pounds of
dusting sulfur per acre, 14 days after the
second dusting. This should be about
blooming time.

Fourth dusting— 10 to 15 pounds of
dusting sulfur per acre, 14 days after the
third dusting.

Fifth dusting— 10 to 15 pounds of
dusting sulfur per acre, when the berries
are about one-half grown.

Sixth dusting— 10 to 15 pounds of
dusting sulfur per acre, just before the
grapes begin to ripen.

Exceptions— Most American varieties
are resistant enough so that they seldom
need dusting, but all European varieties
are susceptible to mildew and for good
control all such varieties grown in the

coastal section and most of the table-
grape varieties need all 6 dustings.

On raisin and wine grapes grown in
the interior valleys, satisfactory control
has been obtained with a program that
eliminates the fourth and sixth applica-
tions. In the hot Coachella and Imperial
valleys, one application of sulfur (when
the shoots are 15 to 18 inches long) may
suffice.

When powdery mildew becomes con-
spicuous it can not be cured by dusting
with sulfur— a liquid eradicant spray may
then be advisable. Such sprays spot or
stain the fruit and are usually objection-
able—especially on table grapes.

For early season outbreaks, that is until
the berries are about half grown, use a
spray made of % gallon of liquid lime-
sulfur, 5 pounds of wettable sulfur and
a suitable spreader such as blood albu-
men, to 100 gallons of water.

Later in the season, after the berries
are over half grown less objectionable
residue is deposited from a mixture of
1% pounds of potassium permanganate,
1% pounds of sodium silicate, and %
pound of baking soda per 100 gallons of
water. Within 2 days after being sprayed,
the vines must be dusted with sulfur to
prevent a recurrence of the mildew.

Black knot or crown
gall is not serious

Black knot or (when it occurs in the
crown of the plant) crown gall is caused
by a soil-inhabiting bacteria that may be
present in almost any vineyard soil. It
is not generally serious in California
vineyards except during seasons when
the trunks and arms have been cracked
by freezing.

What to look for. Injuries on the
arms and trunk may develop tumorlike
spongy overgrowths during the spring
and summer. These overgrowths on the

[58]

aerial parts of the plant often turn dark,
hence the name black knot.

A more common form of the disease
occurs about the crown of the plant, often
just below the surface of the ground and
this form is usually termed crown gall.
The bacteria are usually spread to the
aerial parts of the plant by rains and enter
the tissues through fresh wounds. The
presence of these bacteria in the plant
tissues stimulates the cells to very rapid
growth, resulting in the formation of the
tumorlike overgrowths.

What to do. Since the bacteria may
also be spread from galls to fresh pruning
wounds by the pruning shears, avoid cut-
ting into affected tissue with the shears.

The knots may be removed by pruning
off the affected canes and arms, or by
chiseling out the galls from the trunks
of the vines.

A simple method of killing the galls
is to spray or swab them with a solution
of sodium arsenite (a deadly poison)
made up as described for the control of
black measles (see page 60) . A few weeks
after treatment the galls will usually dry
up, and may then be knocked off.

Pierce's disease in
grapes cannot be cured

This very destructive disease was first
observed in 1884 in southern California
where it was called Anaheim disease, and
California vine disease. Attempts to re-
plant vinifera grape varieties in some of
these same southern California localities
where the disease killed out the vineyards
have not been profitable; the vines died
out within 3 or 4 years after planting.
In other localities, replanting has been
successful.

The disease is now known to be present
in every important vineyard district of
the state, and in some local areas it has
assumed epidemic proportions. It is dis-

cussed more fully in Exp. Sta. Cir. 353,
Pierce s Disease of Grapevines.

The disease is caused by a virus that
is transmissible from diseased plants to
healthy ones. The same virus causes al-
falfa dwarf. Many other plants are also
hosts to the virus which causes this dis-
ease. They include Ladino clover, red
clover, white and yellow sweet clovers,
several grasses and some shrubs. Insect
vectors apparently cause most of the
spread to vineyards, but the disease may
also be carried, to a limited extent, in
buds (for grafting) and in cuttings taken
from diseased vines.

What to look for. The characteristic
symptoms observable in early summer
include delayed starting of growth, leaf
mottling, and dwarfing of the new shoots.
In late summer and fall diseased vines
show burning, scalding, or drying of the
leaves; wilting or premature coloring of
the fruit; uneven maturity of the canes.
Diseased vines die in 2 or more years,
depending on the variety of grape and the
age of the vines. Ribier usually dies within
2 years; Emperor, Malaga, Thompson
Seedless and most other vinifera varieties
die in 2 to 5 years. Some of the American
(slipskin) varieties live much longer.

What to do. No fully effective control
of Pierce's disease is known, nor is any
treatment that will prolong the life of the
diseased vine.

To maintain the vineyard in produc-
tion, remove all diseased vines and re-
plant with healthy vines or with layers
from adjacent healthy vines. The disease
is not carried over in the soil.

Vine mosaic can be
prevented by choice of stock

Vine mosaic occurs in several vineyard
districts in the state. It is a virus disease
that does not appear to spread naturally
over long distances, but is easily trans-

[59]

mitted through any propagating wood.

What to look for. The leaves of dis-
eased vines, from emergence to leaf fall,
show varying degrees and patterns of
chlorosis (discoloring) , mostly of yellow,
cream, and light green areas. The cream
color occurs as a narrow band along the
smaller veins, or as if splattered over
the leaf surface. Some leaves may be en-
tirely yellow, with only traces of green
along the large veins.

In other leaves, a light green color may
appear in the veins and spread, as if leak-
ing, into the surrounding tissue. Many
leaves have 2 or more of the types of
mottling mentioned, with one or another
usually predominating. An occasional
leaf may be covered with a mixture of
types, including some veinlet clearing.
The cream and yellow mottled areas are
usually faint and indistinct in the young
leaves, but as the leaves mature, the mot-
tling becomes prominent, with definite
margins contrasting with the green of
the rest of the leaf.

During the summer and fall the mottled
areas usually fade to light cream or nearly
white, and parts of the leaves may dry up.

What to do. Mosaic may be pre-
vented by care in the selection of bud
wood and propagating stock. All vines
from which cuttings or buds are to be
taken for propagation should be disease
free, and selected and marked during the
summer. This disease is not apparent dur-
ing the dormant season.

Black measles is treated
with a deadly poison

The names black measles, Spanish
measles, and black mildew, are applied
to a peculiar speckling of white or red
grape skins with reddish brown or pur-
plish spots. The cause is not known.

What to look for. In addition to the
spots described above, the grape skins

are sometimes mottled. The fruit of se-
verely affected vines often cracks and
splits open; it may dry up on the vine
before maturing.

Severe fruit symptoms are usually (but
not always) accompanied by discolora-
tion and dropping of leaves, and dying
back of the shoot tips.

The leaves of affected vines develop
various degrees of mottling, bronzing,
spotting, and death of tissue between the
veins. The discolored leaf areas may en-
large into yellow spots which later dry
up and turn brown or red. These symp-
toms are usually most prominent in late
summer, but may occur at any time dur-
ing the growing season.

An entire vine may be affected, but
commonly the symptoms are found on a
single arm or branch. Measles may show
in some vines one season, and not the
next, but badly diseased vines usually
manifest the symptoms every year. In
some vines the disease appears suddenly;
these vines may dry up and drop all of
their leaves within a few days, and some
will die; but many will start new growth
again within a few weeks.

Vines 10 to 15 years old are most often
affected, but some have been attacked at
only 3 years.

What to do. Spray or swab the trunk
and arms of affected vines during the dor-
mant season with a solution of sodium
arsenite containing the equivalent of 2.7
pounds of arsenic trioxide to 100 gallons
of water. Sodium arsenite for this pur-
pose is usually sold as a heavy solution
containing 4 pounds of arsenic as arsenic
trioxide (AS 2 O x ), the equivalent of 6
pounds of sodium arsenite per gallon.
For each 100 gallons of spray, use %
gallon of such material. No spreader is
needed.

Special care should be taken to wet all
old wounds thoroughly, and the treatment

[60]

should be given only after the vines have
become completely dormant. During sea-
sons when the vines never do become
completely dormant, delay the treatment
for another year.

The spray may be applied either be-
fore pruning (but at least 3 weeks after
the first killing frost) or atleast 3 weeks
after pruning, but before the buds swell
in the spring. If a power sprayer is used,
the pressure should not exceed 100
pounds. When treatment is planned, it is
advisable to prune early in December and
spray late in January or February.

Sodium arsenite is very poisonous, and ex-
treme care must be taken to keep it away from
both animals and humans. Avoid getting it on
the skin, or in the mouth or nose of the persons
applying the spray. Since the material is so
poisonous, and if not applied properly may in-
jure the vines, anyone not experienced in its
application is urged to consult the local Farm
Advisor, or someone who is thoroughly experi-
enced with the procedure, and work under his
direction.

Dead arm, or leaf
and cane spot disease

The dead arm disease of the grapevine
is caused by a fungus, and has been found
in nearly all of the grape-growing sec-
tions of the state. The fungus lives over
winter in diseased canes, arms, spurs, and
bits of leaf stems left on the vines. The
fungus can do considerable damage to
the young shoots, leaves and flower clus-
ters. Infection generally occurs in the
spring, when the shoots are young and
tender. The spores are spread from the
old diseased parts of the vine to the young
tissues by late spring rains or dripping
fogs, and the disease is very conspicuous
in late spring.

What to look for. The leaves, leaf
stems, canes, and flower cluster stems de-

velop small, angular spots. Most of these
spots have yellowish margins with dark
centers. Frequently the spots grow to-
gether to form large brown areas with
numerous dark spots in them.

The early rapid growth of the tissues
causes many of the diseased areas to split,
resulting in open, diamond-shaped cank-
ers in the older shoots and canes. In some
cases the diseased areas are so numerous
that the shoots are severely stunted and
some of them may be killed. Generally
the more vigorous shoots will continue
to grow, even though they have become
infected, and later in the summer the dis-
eased portion will appear only at the base
of the cane. In these canes most of the
cankers callus over and there is little indi-
cation of further growth of the diseased
areas during the summer, but in Septem-
ber or October, with cooler weather and
night dews, many of the diseased areas
will resume growth.

Diseased areas on the cluster stems go
into the fruit and cause bunch rot.

Diseased areas on the canes frequently
enlarge and kill a number of buds. In
some cases the fungus grows back into
the wood of the arm, where it gradually
kills the arm— thus the name, dead arm.

What to do. In early December, prune
out all infected wood. Late in January
or in February, spray the vines with so-
dium arsenite solution, using the same
mixture and technique given for black
measles on page 60.

If spraying must be done later, after
the shoots are starting to grow, use a
bordeaux 4-4-100 cover spray.

Collar rot is usually
found in young vineyards

Collar rot is caused by one or more
species of water mold fungi. The disease
is most prevalent in vineyards up to 4 or

61]

5 years old and is seldom found in older
vineyards.

The fungi causing collar rot are fa-
vored by wet soil and usually enter the
grape tissues near the crown of the vine
in the early spring. They kill the cambium
and the bark, forming dead cankers that
often circle the trunk for 3 to 6 inches
near the ground level.

What to look for. Vines girdled by
collar rot may not show signs of the dis-
ease until late in the spring or summer.
The tops of the diseased vines usually
wilt and the vines dry up sometime dur-
ing the summer. Some vines may con-
tinue to grow all summer and only show
signs of early maturity during the fall.

The tissue usually forms a large cal-
luslike overgrowth above the canker.
Sometimes the callous tissues will bridge
over and heal a small canker.

What to do. Satisfactory control
measures are not known, but the diseased
vine may be removed and a new one put
in its place without danger of loss from
transmission of the disease.

Armillaria root rot
requires soil fumigation

This disease, also known as oak root
fungus, is apparently native to Califor-
nia, and is found in several vineyard
areas of the state. It causes a rot of roots
and trunks of many trees and shrubs as
well as of vines.

What to look for. The first indica-
tion of its presence is usually a decline
in vigor; growth stops and the foliage
turns yellow. In following seasons, as a
rule, cane growth is weak and the leaves
are small. The vines often die suddenly
after displaying some of these signs.

White, fan-shaped plaques of the fun-
gus can usually be found spreading be-
tween the layers of the bark, and between
the bark and the wood. Infected roots

and underground trunks may have small,
black, somewhat smooth and shiny,
threadlike strands on the surface and
penetrating into the bark. In the fall and
winter, after the rains start, clumps of
mushrooms may also appear at the base
of affected vines.

What to do. Soil treatment with car-
bon disulfide is the most promising rem-
edy, and though expensive, is warranted
in vineyards that have relatively small
infected areas.

Application should be made in sum-
mer, or early fall, when the soil is fairly
dry. Clear the area to be treated by re-
moving all vine trunks and roots to a
depth of 12 inches. Pulverize the surface
to form a loose mulch then wet it 2 or 3
inches deep by sprinkling, to form a seal
and prevent the gas from escaping from
the soil.

While the surface is still wet, inject the
carbon disulfide 6 to 8 inches deep, in
holes 18 inches apart, staggered in rows
18 inches apart. Apply 2 ounces by
weight (1% ounces by volume) of carbon
disulfide in each hole and plug up the
hole by packing the soil with the heel of
the shoe. Pack the entire surface by drag-
ging, rolling or tamping and then re-wet
the surface by sprinkling or spraying.

The treatment outlined should kill the
fungus to a depth of 5 or 6 feet in sandy
or loam soils. If the vine roots go deeper,
the dosage should be increased accord-
ingly. Treated areas may be safely re-
planted the following spring.

The effectiveness of this treatment is
hard to determine until 3 or more years
after replanting. In some vineyards where
the method was used, parts of the area
have had to be retreated. In other vine-
yards, diseased vines showing at the mar-
gins of the treated plots indicate that the
application did not include all of the af-
fected vines.

[62]

Little-leaf will cut down
yield of the vines

As the name implies, vines affected
with little-leaf disease have small leaves,
especially toward the shoot tips and on
lateral shoots. The crop is diminished,
even on vines that are only slightly af-
fected; the clusters tend to be straggly
and have many small, round, seedless
(shot) berries. Badly affected vines may
produce little fruit.

What to look for. The leaves, par-
ticularly near the tip of the shoots, in
midsummer become variegated or mot-
tled; the tissue close to the veins is the
greenest, and the areas between the veins
are whitish or yellowish green. The color
differences vary from inconspicuous to
very pronounced.

In severe cases the veins in the leaves
tend to course closely together so that
the leaf becomes more like a partly
opened fan, without the normal indenta-
tion at the base. Seemingly the tissue be-
tween the veins does not expand normally
so that they are held closely together.

The canes of vines affected by little-
leaf often produce numerous lateral
shoots which have short spaces between
the nodes and very small leaves. These
give the vine a brushy appearance.

What to do. With spur-pruned vines,
the best remedy is to paint or swab the
pruning cuts at the ends of the spurs,
within a few minutes after pruning, with
a solution of 2 pounds of zinc sulfate to a
gallon of water. Sometimes, when zinc has
been applied in cold weather, with the
soil very dry, buds on many spurs have
been injured or killed; hence, under such
conditions only 1% pounds of zinc sul-
fate to 1 gallon of water should be used.

On cane-pruned vines this treatment
has not proved adequate. Other treatments
tried, such as leaf and dormant sprays,

injections of the vine, and soil applica-
tion of zinc have given no better results.

Phylloxera must be
avoided by use of stock

In California, phylloxera, an insect re-
lated to and resembling the aphids, at-
tacks only the roots of grapevines. It
causes serious trouble, for, once a plant-
ing is infested, little or nothing can be
done, and the vines usually die out in
three to ten years.

Southern California is still relatively
free from phylloxera. In the San Joaquin
and Sacramento valleys, Stanislaus, Mer-
ced, and Tehama counties are free; and
Kern, Kings, and Madera counties have
only localized areas of infestation. Phyl-
loxera-resistant stocks are required in
and adjacent to the infested areas. The
farm advisor or the agricultural commis-
sioner may be consulted for information
regarding danger zones. San Joaquin
County and the entire Sacramento Valley,
with the exception of Tehama County,
have many local areas of infestation; in
the older vineyard areas phylloxera-
resistant rootstocks are advised for loam
and heavier soils. New lands not adjacent
to other vineyards and not irrigated with
river or creek water may be planted to
own-rooted vines with reasonable safety.
Fresno and Tulare counties have large
areas of general infestation, particularly
east of the city of Fresno and in the
Dinuba-Cutler-Yettem area. Many other
smaller danger zones occur. Although
these two counties still contain large areas
of uninfested land, any grower planting
vines on soils of sandy-loam or of heavier
texture is advised to investigate the prob-
able danger. If no phylloxera is present
within a half mile, he will probably get
the best vineyard from rootings of the
desired fruiting variety. If phylloxera
occurs in his soil or in an adjacent vine-

[63

yard, resistant rootstocks are advised.
The entire north coast region (except
parts of San Benito County) is widely
infested; resistant rootstocks are there-
fore generally required and are advised
for all new plantings in the coastal val-
leys and adjacent rolling lands.

What to look for. On the young root-
lets, the feeding of the insects causes small
swellings, and these give a contorted
(hooked) appearance and check the
growth. On the larger roots small galls
are formed, which later decay and dis-
rupt the functioning.

What to do. Control consists in graft-
ing the fruiting varieties on rootstocks
resistant to phylloxera. Establishment of
such vineyards is discussed under propa-
gation.

Once an area becomes infested, it
remains so as long as any grapevines sur-
vive. In infested areas own-rooted (un-
grafted) vines of vinifera varieties cannot
be grown except on very sandy soils. The
American varieties have varying degrees
of resistance. In sandy loam and heavier
soils the phylloxera is more serious and
spreads more rapidly than in sandy soils.
Vines growing in soil so sandy that it
does not crack when dried after a thor-
ough wetting are unlikely to be attacked.

Most resistant rootstock varieties are
hybrids, artificially produced by crossing
two or more grape species. A very small
number are selections from wild vines.
Hundreds exist, but only a few varieties
are used commercially in California.

Rupestris St. George is the standard
phylloxera-resistant stock for wine-grape
varieties on the nonirrigated soils in the
coastal valleys of California. Under these
conditions it is recommended, and is used
almost exclusively. It is not resistant to
nematodes.

Aramon x Rupestris No. 1, in irrigated
soils that are free from nematodes, usu-

ally surpasses St. George in growth and
productivity of the grafted vines. It is
less resistant to phylloxera than St.
George and is even more susceptible to
nematodes than most of the fruiting vari-
eties. Commercially it appears to be the
best stock available for wine-grape varie-
ties in irrigated loam soils of the great
central valley of California. It also does
well in deep, moist soils in the coastal
valleys, but it is not recommended for
dry hillside land. In the sandy, nematode-
infested soils found in the San Joaquin
Valley, it is practically worthless.

Solonis x Othello 1613 is moderately
resistant to phylloxera and highly resist-
ant to the root-knot nematode. In fertile,
irrigated, sandy-loam soils in the San
Joaquin Valley it is usually the best root-
stock available. It is not known to be
incompatible with any variety except,
perhaps, Ribier. In nonirrigated soils
and in very poor sandy soils the grafted
vines are likely to be weak and unproduc-
tive; in loam and heavier soils they are
not equal to the Aramon x Rupestris No.
1 stock in vigor and productivity, but are
often superior in the quality of their table
grapes.

Dogridge and Salt Creek are extremely
vigorous nematode-resistant rootstock va-
rieties. They are available only in limited
quantity. Being still in the experimental
testing stage, they should be tried only
in very sandy soil of low fertility where
vines on Solonis x Othello 1613 are too
weak to give satisfaction. In fertile sandy
or sandy-loam soils the vines often grow
with such extreme vigor that they are un-
productive.

Nematodes are worst
in sandy soils

Nematodes are small worms that live
on the surface of the roots or bore into
the roots and live there. Of the several

[64]

varieties that attack grapes, the rootknot,
or garden, nematode is the most common.
It causes, on the roots, swellings and dis-
tortions which may sometimes be mis-
taken for phylloxera. Though apparently
all vinifera grapes are susceptible, varie-
ties differ slightly in the extent of nema-
tode injury. Thompson Seedless will do
fairly well in some places where Red
Malaga and Ribier are failures.

In very sandy soils heavily infested
with nematodes, one may find it impos-
sible to grow grapes except by using
nematode-resistant rootstocks. Loam and
clay-loam soils are not often seriously af-
fected. Resistant rootstock varieties are
discussed in the section on phylloxera.

Grape leafhoppers are
controlled by DDT

Grape leafhoppers are whitish green
insects, about % inch long, narrow, with
red markings. They seem to increase and
decrease in cycles and during certain
periods have severely injured vineyards
in the San Joaquin Valley and other re-
gions.

What to look for. Leafhoppers suck
the juices from the leaves, making min-
ute, whitish spots. When abundant, their
feeding injury causes the leaves to drop
prematurely. They also soil the fruit with
black specks of their droppings.

There are usually 2 or 3 broods each
season and the adults overwinter.

What to do. One pound of DDT per
acre, as a wettable powder spray, or as
a dust, applied before blossoming, kills
the overwintered hoppers. The residue
remaining on the leaves kills the young
hoppers as they hatch.

DDT is most often applied as a dust
containing 5 per cent DDT and 50 per
cent sulfur, at the rate of 20 pounds per
acre. Better coverage, by driving the
duster through every middle row, instead

of every other row, gives better control.

An effective control, with better DDT
persistence, may be obtained with a 2.4
per cent DDT solution in a light oil, at
the rate of 3 to 4 gallons per acre, ap-
plied with vapo-spray equipment.

In late summer and fall DDT appears
to lose much of its effectiveness against
adult hoppers. There is also some evi-
dence to show that the use of DDT favors
the increase of red spiders.

Pyrethrum. In the early spring, after
the green shoots appear, the overwinter-
ing adults seek them to feed and to lay
eggs. At this time, one may kill them and
in isolated vineyards accomplish effec-
tive control by spraying with an oil solu-
tion of pyrethrum; special "vapo-spray"
equipment should be used but not an
ordinary spray rig. Only about 3 gallons
is required per acre. The spray must be
applied as soon as the overwintering
adult leafhoppers have migrated into the
vineyard— that is, about 10 days after
growth starts in the spring.

Nicotine. The wingless nymphs of the
first brood appear in May and early June.
Just as the oldest nymphs are growing
wings, the vines may be treated with a
spray consisting of 1 to 1% pints of nico-
tine sulfate (40 per cent) per 100 gallons
of water, together with an appropriate
spreader, such as soap. The effectiveness
of the spray is increased by adding %
pound of lye per 100 gallons to make it
alkaline. In the application, care must be
taken to wet the hoppers on the lower side
of the older leaves. To do an effective job,
one must direct the spray from the noz-
zles upward.

Calcium Cyanide. Late in the season,
when most of the hoppers are adult and
very numerous, treating the vines with
calcium cyanide dust is effective. This
dust should be applied with power ma-
chinery, and the weather conditions must

[65]

be favorable— that is, without wind and
with fairly high humidity. In the San
Joaquin Valley such conditions are most
frequently obtained in the early part of
the night.

Since calcium cyanide dust produces a poi-
sonous gas, it should be handled with care. The
operators of the dusting equipment should wear
adequate gas masks. This material should not
be applied with horse-drawn dusting machines,
nor in the immediate vicinity of farmyards con-
taining poultry or livestock.

Red spiders are
difficult to control

There are 2 different red spiders that
are injurious to grapes— the Pacific mite
and the Willamette mite. The Pacific mite
causes serious damage in the territory ex-
tending from Fresno north; the Willam-
ette mite is distributed throughout the
state, but gives little trouble north of
Fresno.

What to look for. First symptoms of
infestation are yellow spots on the leaves,
showing where the spiders are feeding.
The adults, having overwintered beneath
the rough bark on the trunks and arms
of the vines, emerge in the spring and
migrate to new shoots. As the season ad-
vances the population increases so that
by midsummer or late summer the mites
may injure the plants enough to cause
leaves to drop before the fruit is ripe.
This causes a marked reduction in sugar
and a very poor quality at harvest. Sev-
eral consecutive years of this trouble will
result in weak, stunted, devitalized vines.

What to do. From Fresno north, the
Willamette mite is controlled by sulfur
dust applied for mildew control. At
Fresno, and south, this pest is not killed
by sulfur so it is necessary to control it
with mitacides as discussed below for
Pacific mites.

At this writing, the control of the

Pacific mite is in a condition of rapid
evolution. Early practices of oil spray-
ing, banding plus suckering, and DN
dusting have been largely replaced by
dusting with 2 different ethyl phosphate
compounds, parathion, and tetraethyl
pyrophosphate.

These dusts are applied when the first
yellow spots appear on the leaves, as a
result of the red spider feeding. Tetra-
ethyl pyrophosphate dust is used at con-
centrations of from 0.66 to 1 per cent.
Parathion dust is used at 2 per cent.
Tetraethyl pyrophosphate will not kill
mites before they have emerged from the
eggs, so a second application, 6 days after
the first, is necessary to kill mites that
have hatched from the eggs after the first
dusting.

WARNING— Tetraethyl pyrophosphate (TEPP)
and parathion are known to be very poisonous
to man and to domestic animals. Because of the
high toxicity of these materials, persons electing
to use them are cautioned to follow implicitly all
of the safety precautions given by the manu-
facturers.

Several new miticides, relatively non-
toxic to man, are now available to grow-
ers, but at present these are only used as
water-borne sprays. The present avail-
able information on some of these ma-
terials is as follows:

Neotran (dichlorophenoxy methane)
is marketed as a 40 per cent wettable
powder. Use 2 pounds in 100 gallons of
water and spray very thoroughly. This
product may leave an objectionable white
deposit on table grapes.

Dimite (diparachlorophenyl methyl
carbinol) is marketed as a 25 per cent
emulsible liquid. Use 2 pints of this fab-
rication in 100 gallons of water and spray
thoroughly.

Aramite (chloroethyl tertiary butyl-
phenoxy methyl ethyl sulfite) is marketed

[66]

as a 15 per cent wettable powder. Use 1
pound in 100 gallons of water and spray
thoroughly.

Grape leaf folders
are easy to identify

Occasional infestations of the grape
leaf folder have assumed serious propor-
tions. In the middle San Juaquin Valley
there are apparently 3 broods a year.

What to look for. The presence of
the insect in the vineyard may be de-
tected by the characteristic rolling of the
leaves— one edge being rolled up rather
tightly, making a tube about the diameter
of a lead pencil. The insect lives in this
tube.

What to do. Best control is obtained
by treating for the first brood of larvae,
and then treating again, about 2 months
later, for the second brood.

For the first brood, use a 50 per cent
cryolite dust, applied early in May. Sul-
fur and DDT may be mixed with the
cryolite for control of mildew and grape
leafhoppers at the same time.

An alternate method for the first brood
is to spray with basic arsenate of lead at
4 pounds in 100 gallons of water.

For the second brood dust with 50 per
cent cryolite dust at 20 to 25 pounds per
acre, applied early in July.

Bud mites cannot
be controlled

Bud mites are too small to be seen with
the unaided eye. They multiply rapidly
and cause considerable damage to crops.

What to look for. Infestation causes
a dwarfing and stunting of new canes by
causing a shortening of the cane between
the lower nodes. Sometimes the terminal
bud of the new shoot is killed and 5 or 6
lateral buds push out together, making a
"witches broom." In severe cases all win-
ter buds on all spurs are killed and the

vine produces nothing but suckers. Other
symptoms are flattened canes and zig-zag
shoots.

No satisfactory control is known at the
present time.

Grape bud beetles are
controlled with DDT also

The grape bud beetle is only injurious
in certain areas of the state, notably in
Fresno County and in the Coachella Val-
ley. The beetles are light gray and about
% inch long. They live in the ground,
feeding on the roots of the vines and
emerge in the spring to lay eggs in the
bark of the vine. After hatching, the lar-
vae drop to the ground again and the
cycle continues.

Late developing grape varieties are
more severely damaged than those whose
buds start to grow rapidly before the
beetles appear in the spring.

What to do. Control is obtained by
spraying or dusting with DDT as de-
scribed below for cutworms.

Hoplia beetles are
controlled with lindane

Hoplia beetles are between % and %
inch in length, with reddish brown wings
and bright silver or gold color on the
lower side of the body.

In the spring the adult beetles emerge
from the ground and feed on grape flower
buds and flowers.

What to do. Apply % per cent lin-
dane (gamma isomer of benzene hexa-
chloride) dust at the rate of 20 pounds
per acre, during the pre-bloom period.

Cutworms do their
damage at night

Cutworms are the larvae of certain
night-flying moths. They usually remain
in the ground during the day, but come
up on the vines and feed on the opening

[67

buds or the tender young shoots. Buds
and shoots are often killed by these pests.

What to do. Use a dust containing
5 or 10 per cent DDT. Apply with a hand
duster, if possible, to give a heavy, visible
deposit on the trunk and arms of the
vine.

As an alternative, a full-dilution spray,
containing 1% pounds of 50 per cent
wettable DDT, plus % gallon of medium-
grade oil (as an adhesive) per 100 gal-
lons of water, may be used. In this case,
the trunk and arms of the vines should
be thoroughly wetted.

A fast method of spraying consists of
using a low volume mixture of 6 pounds
of 50 per cent wettable DDT, plus 1 gal-
lon of medium-grade oil per 100 gallons
of water. In this method the rig moves
rapidly, directing the spray at the arms
and spurs, and applies about 100 gallons
per acre.

The DDT dust or spray should be ap-
plied as soon as the buds begin to swell.
If heavy rains wash the DDT from the
vines, it may be necessary to treat the
vineyard again.

Rabbits may feed
on the younger vines

In newly planted vineyards rabbits
sometimes damage or destroy vines by

chewing the leaves and bark. They may
continue night after night and by con-
tinued eating will weaken or kill vines.
Such damage may be local, in one part
of a vineyard.

What to do. The most effective pro-
tection from rabbits is to fence off the
susceptible area with 1%-inch poultry
mesh. The fence should extend at least
30 inches above the ground and with
about 6 inches of wire buried in the soil
to prevent burrowing. Grape stakes will
serve as posts.

When only a few vines are attacked,
they may be protected with cylinders or
cones of poultry netting.

Many chemicals and other substances,
such as slaughterhouse blood have been
tried as repellants, but with little success.
Repellant 96A, sold by the U. S. Fish and
Wildlife Service, Pocatello, Idaho, has
given protection to vines and other crops
in some regions.

Tests of this material on older grape
vines at Davis during the summer showed
no evidence of burning.

The control of gophers, moles, ground
squirrels and other burrowing animals is
thoroughly covered in Extension Circular
138, Control of Field Rodents in Califor-
nia, by Dr. Tracy I. Storer.

arieties • • . here is a description of
those more commonly grown in the state

Probably 8,000 varieties of grapes have
been named and described. In California
about 20 per cent of this number are
growing somewhere in the vineyards,
gardens, and variety collections, though
not more than 50 or 60 can be considered
as important commercial varieties.

In the following paragraphs an at-
tempt has been made to give the purpose,

importance, and adaptability of each of
the most common commercial varieties
of raisin, table, and wine grapes now
being grown in California. A brief horti-
cultural description is included; but long,
detailed, technical accounts have been
purposely avoided.

The popular name in California is
given first. The name in parenthesis is

[68

the name most commonly used elsewhere
in the world.

Raisins come mostly
from three varieties
Thompson Seedless {Sultanina).

Well over half the world's raisins and
about 90 per cent of California's are
made from Thompson Seedless which
originated in Asia Minor and was first
grown in California by Mr. William
Thompson near Yuba City. It is called
Oval Kishmish in the eastern Mediter-
ranean regions, Sultana in Australia and
South Africa.

In California about one third of the
total grape acreage is Thompson Seed-
less. Besides being the principal raisin
variety it is a leading table grape; but
for the production of table grapes the
vines are usually girdled to make the
berries larger and to improve shipping
quality. From it are also made large quan-
tities of white dessert wines and much
distilling material to furnish alcohol for
arresting the fermentation of other des-
sert wines.

The clusters are large; heavily shoul-
dered, long cylindrical; and well filled.
The berries are uniform, medium-sized;
ellipsoidal elongated; greenish white to
light golden; always seedless; firm and
tender in texture; neutral in flavor; very
sweet when fully ripened; and moder-
ately tender-skinned. As the berries are
somewhat weakly attached to the stems,
causing the clusters to "shatter" in
transit, the shipping quality of the fresh
grapes is only fair. The ripening period
is early. The grapes dry easily into raisins
of soft texture and excellent quality. The
vines are very vigorous and very produc-
tive. Cane pruning is required.

The Thompson Seedless is well adapted
to all parts of the San Joaquin Valley
where grapes are grown and to the

warmer parts of the Sacramento Valley.
In the hot desert it does better than any
other variety tried. It is unsuited to the
cooler regions.

A pink variation— Sultanina rose— is of
interest for home use. Except for its pink,
or rose, color it is almost identical with
the Thompson Seedless.

Muscat of Alexandria. The Muscat
of Alexandria is a very old variety of
North African origin, from which are
made the raisins of Spain— the cluster
Malagas and the stemmed Valencias or
Muscatels. Muscat accounts for less than
10 per cent of the California production
of raisins, but it is an important raisin
variety in Australia.

As a table grape it is highly esteemed
for home gardens and local markets. Its
pronounced flavor, large size, and juicy,
but not watery, pulp make it a favorite
with nearly all who are familiar with it.
It has fair shipping quality, the bloom is
easily rubbed off in handling, leaving ex-
posed its dull-green ground color. It lacks
the attractive appearance necessary to
stimulate sales of any fresh fruit and is
therefore relatively unimportant in table-
grape shipments to eastern markets.

As a wine grape the Muscat of Alexan-
dria is extensively used for muscatel, a
dessert wine. Much of the crop is used
for this purpose. Dry wines made from
it are only standard to mediocre.

The clusters are medium-sized; shoul-
dered, conical; and loose, often straggly.
The berries are large, obovoid, dull green,
normally seeded, pulpy, and strongly
aromatic (Muscat) flavored. The mod-
erately tough skins are covered with a
gray bloom, easily rubbed off. The ripen-
ing period is late midseason, and the
grapes dry easily into large raisins of
soft texture and excellent quality. The
vines are medium in vigor and are very
productive ; they are usually head-pruned.

In some regions and in many soils the
flowers set poorly; the results are strag-
gly clusters, many shot berries, and, fre-
quently, poor crops. Often the setting of
the flowers can be improved by painting
the pruning wounds with zinc sulfate as
recommended for little-leaf, or by longer
pruning and flower-cluster thinning.

The Muscat of Alexandria is adapted
only to hot regions. It thrives in most of
the grape-growing areas of the San Joa-
quin Valley, the warm parts of the Sacra-
mento Valley, and the warm valleys of
the south coast region. It is not suited,
however, to the hot desert because of its
tendency to sunburn under conditions of
extreme heat.

A pink variation—Flame Muscat— un-
important in California, is grown in
South Africa under the name Red Hanne-
poot.

Black Corinth {Zante Currant). For
over five hundred years Zante currant
raisins have been made in Greece, where
the variety probably originated and
where most of the world's supply was
produced.

The clusters are small to medium in
size; winged, uniformly cylindrical; well
filled to compact when the vines are
girdled, but straggly on ungirdled vines.
The berries are very small; spherical to
oblate; reddish black; mostly seedless,
with an occasional seeded berry of me-
dium size; very juicy; neutral in flavor;
and have very thin and tender skins. They
ripen early and dry easily into very small
raisins of soft texture and pleasing tart
taste.

The vines are vigorous and— if girdled
—productive. They may be cane- or cor-
don-pruned.

The Black Corinth is well suited to the
central and lower parts of the San Joa-
quin Valley. It has also done very well
in experimental plantings at Davis.

Seedless Sultana {Round Seed-

/ess).This grape resembles the Thompson
Seedless but differs in having smaller,
oblate to round berries, a few of which
contain partly hardened seeds. It has been
largely displaced by the Thompson Seed-
less.

Table grapes include
many varieties

Thompson Seedless. For discussion
of the Thompson Seedless variety, see
"Raisin Grapes."

Flame Tokay. Formerly the Flame
Tokay was California's premier table-
grape variety. It is now surpassed by
both the Thompson Seedless and the Em-
peror. It owes its importance primarily
to its brilliant red color and to its good
shipping and keeping qualities.

The variety apparently originated in
Kabylia, a province of Algeria, where it
is known by the Arab name of Ahmeur
bou Ahmeur.

The clusters are large; shouldered,
short conical; and compact. The berries
are large to very large; ovoid truncate;
brilliant red to dark red; normally
seeded; very firm; neutral in flavor; and
have thick, fairly tough skins. The stems
are large and tough, and the berries ad-
here firmly. The grapes ripen in late mid-
season. They are sensitive to sunburn.
The vines are usually head-pruned, but
will do well when cordon-pruned.

The principal producing area is around
Lodi, in the cooler part of region 4.
There are other areas of lesser impor-
tance in Sacramento County, and a few
scattered commercial plantings elsewhere
in the state. In the hotter regions the
variety does not color well and sunburns
badly, whereas in the cooler coastal sec-
tions it does not ripen well.

Emperor. The origin of the Emperor
is unknown. First in popularity as a table

70]

variety, it owes its importance to its late
ripening, its attractive appearance, and
its excellent shipping and storage quali-
ties. Large quantities are held in cold
storage to extend the marketing season.

The clusters are large in size; long
conical; and well filled. The berries are
uniform, large; elongated obovoid or
ellipsoidal; light red to reddish purple;
normally seeded; moderately firm; neu-
tral in flavor; and have thick and tough
skins. The stems are tough, and the ber-
ries adhere very firmly. The variety
ripens late. The vines are very vigorous
and productive. They are cordon-pruned;
often short cordons are supplemented
with short fruit canes at the ends of the
branches. The latter practice is losing
favor since the canes are often overloaded
and the fruit is of poorer quality.

The Emperor is profitable only when
it attains a red color and a large berry
size. It most nearly attains perfection
near the foothills along the east side of
the San Joaquin Valley in Tulare and
Fresno counties, in region 5. About 90
per cent of the Emperors are produced in
this area.

Malaga. The Malaga, once Califor-
nia's leading table-grape variety, has been
largely replaced in the market by the
Thompson Seedless (from girdled vines) .
As a table grape the Malaga now occupies
a relatively minor position, and most of
the production is used for distilling ma-
terial or low-grade wines.

The clusters are large to very large;
conical; and well filled. The berries are
uniform, large; ellipsoidal; whitish green
to whitish yellow; normally seeded; firm;
neutral in flavor; and have thick, moder-
ately tough skins. The stems are tough,
and the berries adhere firmly. Shipping
and keeping qualities are very good. The
vines are vigorous and very productive.
Although cordon pruning is best, head

pruning is satisfactory. The ripening
time is midseason.

The Malaga, being suited only to the
warmer regions, is grown in various parts
of the San Joaquin Valley.

Red Malaga (Mol/nera). The clus-
ters of Red Malaga are very large ; widely
branched and irregular in shape; and
loose to well filled. The berries are large;
spherical to short ellipsoidal; pink to
reddish purple, often faintly striated;
normally seeded; very crisp and hard;
neutral in flavor; low in acidity; and
tender-skinned. The stems are tough ; the
berries are firmly attached. Shipping and
keeping qualities are fair. The vines are
very vigorous and productive when cor-
don-pruned or long-pruned and flower-
cluster-thinned. The grapes ripen in early
midseason, usually just prior to the
Malaga.

The Red Malaga is well suited to most
of the San Joaquin Valley, where it ripens
earlier and can be marketed before the
Flame Tokay of the intermediate central
valley region. After the Flame Tokays
start to market, the demand for Red
Malaga decreases.

Ribier {Alphonse Lavallee). This
beautiful table grape, misnamed Ribier
in California, is one of the finest of the
European hothouse varieties; the grape
grown in California is the Alphonse La-
vallee and not the Gros Ribier of Europe.
Although it is the principal black table
grape in the state, in total production it
ranks fifth or sixth among all table-grape
varieties.

The clusters are medium in size; short
conical, often heavily shouldered; vary-
ing from loose to compact. The berries
are very large; oblate to ellipsoidal in
shape; jet black; normally seeded ; firm;
neutral in flavor but mildly astringent;
low in acid; and moderately tough-
skinned. The stems are tough, and the

[71

berries firmly attached. The shipping
quality is good; the keeping quality excel-
lent. The vines are moderately vigorous
and very productive. They are cordon-
pruned and ripen in early midseason.

The Ribier is best suited to the warm
middle and upper San Joaquin Valley.

Almeria (Ofianez). Spain produces
and exports large quantities of Almeria,
a late table grape, packed in granulated
cork. The variety is not of great impor-
tance in California because of its suscep-
tibility to Ohanez spot, apparently a form
of heat injury.

The clusters are medium or medium
large; short conical; and well filled to
compact. The berries are medium large;
cylindroidal; greenish white; normally
seeded; firm; neutral in flavor; and have
thick and tough skins. The stems are
tough, and the berries firmly attached.
Shipping and keeping qualities are excel-
lent. The vines are vigorous, and usually
productive when they are cane-pruned.
The variety does best when trained on
arbors, and when a large frame of perma-
nent wood is developed. The fruit ripens
late.

The Almeria has been successful only
in local areas in Tulare County, on the
east side of the San Joaquin Valley.

Cornichon {Olivette noire). The
production of Cornichon has gradually
decreased until now it is only of minor
importance.

The clusters are medium to large; coni-
cal, often winged; and well filled. The
berries are large; ellipsoidal elongated;
reddish black with abundant bloom; soft
and juicy; neutral in flavor; and have
thick, tough skins. The shipping and
keeping qualities are only fair. The vines,
though vigorous, tend to bear irregu-
larly. The fruit ripens in late midseason.

The Cornichon does best in the inter-
mediate central valley region.

Olivette blanche. The very large
size and regular, elongated shape of the
Olivette blanche make it an attractive
table grape. Because of its poor shipping
quality, it is of only minor importance.

The clusters are very large; irregular
conical; and well filled. The berries are
very large; uniform ovoid elongated, al-
most pointed; bright greenish to greenish
white, often with a pink blush; neutral
in flavor; low in acid; firm and tender;
thin-skinned, easily bruised, and inclined
to discolor where bruised. The stems are
somewhat brittle. The vines are very
vigorous and productive if cane-pruned.
The fruit ripens in late midseason.

The Olivette blanche does well in all
grape-growing areas of the San Joaquin
and intermediate central valley regions.

Rish Babes. The very much elongated
berry of the Rish Baba, a variety of Per-
sian origin, has given it about the same
importance as the Olivette blanche. Both
have been indiscriminately marketed as
"Lady Fingers." Both have essentially
the same merits and defects.

The clusters are medium in size; long
cylindrical; very loose. The berries are
large; much elongated, with one side
nearly straight, the other bulged near the
middle, and the ends rounded; pale
greenish white to light yellow; neutral
in flavor; very low in acid; very tender;
and are thin-skinned and easily bruised.
The stems are brittle. The vines are vigor-
ous, and moderately productive when
cane-pruned. They ripen early midseason.

The Rish Baba does best in the inter-
mediate central valley region.

"American" varieties. Certain of
these varieties having the labrusca, or
"foxy," flavor are much desired by for-
mer residents of the middle western and
eastern states where such grapes are com-
mon. Some can be grown fairly satisfac-
torily in the cooler parts of the California

[72]

coastal valleys and mountain areas. Even
in favored locations the quality of fruit
obtained is inferior to that of the same
varieties produced in good locations in
the East and the Middle West. Their use-
fulness in California is limited to home
gardens and local markets.

Wherever grown they should be trel-
lised, cane-pruned, and irrigated fre-
quently. Being more resistant to powdery
mildew than the vinifera grapes, they
need be sulfured usually only once or
twice each season, often not at all. Other-
wise their culture and care is the same
as for vinifera varieties.

The best for California planting are
as follows: black— Concord and Pierce;
red— Agawam, Iona, Vergennes, Dela-
ware, and Catawba; white— Niagara and
Golden Muscat.

Table-grape varieties of minor
importance. Of the many other known
varieties of table grapes, those listed in
table 5 possess qualities that make them

suited to home gardens and local markets.
Some of these are poor shippers and
others have not been tested in transit.

Black wine grapes
for making red wines

Zinfandel. In acreage and total pro-
duction the Zinfandel is the leading wine-
grape variety of California. It is of
unknown origin and is not grown exten-
sively in any other country. The wine,
which has a characteristic flavor, is of
medium acidity and color. The variety
is best suited to the cooler districts for
the production of dry wines. In the hotter
districts it raisins and sunburns badly
and, particularly in irrigated vineyards,
it is very susceptible to bunch rot.

The clusters are medium-sized; winged
cylindrical; and well filled to very com-
pact. The berries are medium-sized;
spherical; reddish black to black; juicy
in texture. The apical scar is irregularly
shaped and slightly depressed. The grapes

Table 5
LESS-KNOWN TABLE-GRAPE VARIETIES

Variety

Period of
maturity

Color of
berry

Size of
berry

Shape of
berry

Special characteristics

Black Hamburg

Black Prince

Chasselas dore

Chasselas rose

Damas rose

Danugue

Medium

Early

Medium

Late

Medium

Early

Late

Medium

Late

Medium

Very early

Early

Late

Medium

Black

White

Red

Black

White

Reddish black

Pink

Black

White

Black

Reddish black

Black

White

Black

Pink

Large

Medium

Very large

Large

Medium

Large

Very large

Large

Medium

Large

Medium

Spherical

Ellipsoidal

Obovoid

Spherical

Ellipsoidal

Cylindroidal

Spherical

Ellipsoidal

Spherical

Ovoid

Ellipsoidal

Crisp texture

Soft texture
Very large clusters
Pleasing flavor
Seedless — Slight Muscat
Good keeping qualities
Muscat flavor

Dattier

Delight

Ferrara

Flame Muscat

Gros Colman

Italia

Khandahar

Muscat flavor

Brittle stems

Good keeping qualities

Seedlessness

Muscat flavor

Seedless

Tough skins

Seedlessness

Milton

Monukka

Muscat Hamburg

Pearl of Csaba

Perlette

Prune de Cazouls ....
Sultanina rose

[73

ripen in early midseason. The vines are
moderately vigorous and very productive.
Head pruning is recommended.

The Zinfandel, though best adapted to
the coastal valleys, is also grown exten-
sively in the intermediate central valley
region. The best dry wines of this variety
are made from grapes grown in the
cooler regions.

Carignane. Although of Spanish ori-
gin, the Carignane has been grown in
the south of France probably since the
twelfth century. There, and in Algeria,
it is one of the most important varieties.
It is most useful in California for the
making of bulk red wines. Carignane
wines are of medium acidity and color
but have usually no striking varietal char-
acteristic. Being very susceptible to pow-
dery mildew, this grape should not be
planted where control of this disease is
difficult, as in locations subjects to fre-
quent summer fogs.

The clusters are medium-sized; shoul-
dered cylindrical; well filled to compact.
The berries are medium-sized; ellipsoi-
dal; and black with a heavy blue-gray
bloom. They ripen in late midseason. The
vines are very vigorous and very produc-
tive. The canes are large, semierect to
erect in habit of growth. Head pruning
is recommended.

The Carignane, though extensively
grown in nearly all wine-producing dis-
tricts of the state except the coolest, is
best adapted to fertile soils in the warmer
parts of the coastal valleys and in the
intermediate central valley region.

Alicante Bouschet is one of the few
varieties— Grand noir, Petit Bouschet,
and Alicante Ganzin— that have red juice.
Of these it is grown most extensively.
Wines made from it have no character
or merit. The color, especially in new
wines, is intense but fades with age; the
acidity is low. In fertile soils the variety

is very productive. As the grapes have
fair shipping qualities, many are sent to
eastern markets.

The clusters are medium-sized; shoul-
dered conical; and well filled to compact.
The berries are medium-sized; spherical;
brilliant black with a blue-gray bloom.
They ripen in late midseason.

The Alicante Bouschet is suited best
to fertile soils in the warmer parts of
the coastal valleys and in the intermediate
central valley region. Additional plant-
ings in California are not recommended.

Petite Sirah. In suitable locations this
variety yields well and is valuable for
red table wine. Wines properly made
from it are of good quality, with a dis-
tinctive, recognizable flavor and moderate
acidity. The skins have an abundance of
color which is stable. In hot regions or
hot seasons the fruit may sunburn badily.

The clusters are medium-sized ; winged,
cylindrical; and compact. The berries are
medium-sized; slightly ellipsoidal; and
black with a dull bluish-gray bloom. They
ripen in early midseason. The vines are
of moderate vigor and productivity. On
dry hillside soils, short spur pruning is
satisfactory; but in fertile soils, short
cane pruning may be needed.

The Petite Sirah is best adapted to the
valleys of the north coast region, where,
in moderately cool locations, good table
wines may be made from it.

Mataro. Like the Carignane, the Ma-
taro is of Spanish origin and is of value
in California primarily for the producing
of bulk wines. Mataro wines lack striking
varietal characteristics and have low
acidity and color. In most locations the
Carignane is preferred because of its
greater vigor and higher productivity.
The Mataro is less susceptible to powdery
mildew than the Carignane, however, and
also starts its buds slightly later in the
spring, a characteristic that may be im-

[74

portant in locations subject to spring
frosts.

The clusters are medium large ; usually
two-shouldered, conical; and compact.
The berries are medium-sized; spherical;
black with a heavy blue bloom; and firm
pulpy. They ripen in late midseason. The
vines are moderately vigorous; erect in
growth; moderately productive.

The Mataro appears adapted to the
south coast region and to the low foothill
districts on the east side of the lower Sac-
ramento Valley. It should not be planted
in the cooler districts.

Cabernet Sauvignon. The famous
claret wines of the Gironde region of
France derive their flavor and character
from the Cabernet Sauvignon. In suitable
locations in California it produces a wine
of pronounced varietal flavor, high acid-
ity, and good color. It is one of the finest
red table wine varieties in California.

The clusters are small to medium in
size, irregular in shape but often long
conical. They are loose to well filled. The
berries are small; very seedy; nearly
spherical; and black with a gray bloom.
They ripen in midseason. The skin is
tough; the flavor pronounced and char-
acteristic. The vines are very vigorous
and productive with cane pruning. For
satisfactory crops in most situations, long
spur or cane pruning is required.

The variety is best adapted to the cooler
parts of the coastal valleys, where the
grapes attain their highest quality.

Grenache. The Spanish variety Gre-
nache is grown in California largely for
the production of port-type wine, to
which it is well suited. It thrives in the
hot regions, bearing excellent crops. Its
wines are medium low in acidity. In
many locations the grapes are somewhat
deficient in color and must be blended
with other varieties that have more abun-

dant color. The vines are susceptible to
powdery mildew.

The clusters are medium-sized; short
conical, sometimes shouldered or winged;
and loose to well filled. The berries are
small medium; short ellipsoidal, nearly
spherical; and reddish purple to black.
They ripen in late midseason. The stems
of the clusters are very thick. The vines
are unusually vigorous, erect in habit of
growth, and very productive, even when
head-pruned.

The Grenache is probably best adapted
to the hot regions, such as the San Joa-
quin and Sacramento valleys, which pro-
duce the dessert wines. It produces pink
or rose wines of very good quality in the
cooler coastal regions.

Mission. The Jesuit missionaries
planted the first vinifera grapes in Cali-
fornia at the San Diego Mission in the
latter part of the eighteenth century. The
variety was apparently the Mission,
which, until about 1870, was the princi-
pal variety grown in California. Since
then it has been gradually displaced by
other varieties in the coastal regions and
is now grown mainly in the warmer val-
leys, where it is valuable as a dessert-
wine grape. It has always been associated
with the making of sweet white wines,
such as Angelica. It is low in acidity and
too deficient in color to be used alone for
red wines.

The clusters are large; conical, but
heavily shouldered; and stiffly loose-
stems sufficiently rigid to cause the indi-
vidual berries to stand apart. The berries
are medium-sized; oblate; reddish pur-
ple to black; and ripen in late midseason.
The pulp is firm but juicy. The vines are
very vigorous, and single vines occasion-
ally attain enormous size. Given room to
develop, the Mission bears heavily; but
if it is crowded or pruned too short, the
crops tend to be irregular.

[75]

This variety is adapted to the great

central valley and the south coast region.

Black Malvoisie (Cinscfuf). The

heavy-producing variety Malvoisie ap-
pears to have been imported from the
south of France. It is used in California
principally for blending with other vari-
eties in making dessert wines. The grapes
are low in acidity, low in color, and at-
tain a high sugar content before starting
to raisin.

The clusters are medium-sized; winged
cylindrical; and loose to well filled. The
berries are medium large; ellipsoidal;

reddish black to black. Since they ripen
in early midseason and lose water rapidly
after removal from the vine, they soon
become soft after picking. The vines are
vigorous and productive.

Barberct. The very high acid content
of the Barbera makes it valuable for
blending with other grapes for the pro-
duction of table wines in moderately
warm regions. Used alone, it makes a
high-acid wine of considerable character,
which ages slowly.

The clusters are medium in size; coni-
cal; winged, well filled. The berries are

Table 6

IMPORTANT RED-WINE GRAPE VARIETIES NOT EXTENSIVELY

GROWN IN CALIFORNIA*

Variety

Recom-
mended
growing
region t

Period of
maturity

Acidity

Intensity
of color

Produc-
tivity

Type of wine
usually produced

Aleatico

Alicante Ganzin

Aramon

Beclan

Black Prince

Charbono

Fresia

Grand noir

Grignolino

Gros Manzenc

Lagrain

Malbec

Mondeuse

Nebbiolo

Pagadebito

Petit Bouschet

Pinot noir

Refosco

Ruby Cabernet. .
Saint Macaire . . .

Salvador

Sangioveto

Tannat

Tinta amarela .

Tinta cao

Tinta de Madeira

Trousseau

Valdepenas

4-5

4
3-4

2-3

4-5
3
2

4-5
3-4

Early

Medium

Late

Medium

Late

Early

Medium

Early

Late

Early

Late

Medium

Late

Medium

Early

Medium

Early

Medium

Early

Medium

Early

Medium

Early

Medium

Low

Medium

High

Medium

High

Medium

High

Medium

Low

High

Medium

High

Medium

High

Low

Medium

Low

Medium

Low

Very high

Low

Medium

Low

High

Medium

High

Low

High

Medium

High

Medium

High

Medium

High

Very high

Medium

High

Medium

Low

Medium

High

Low

High

Medium

Low

Medium

Low

Medium

Low

Medium

High

Dessert, muscat or

natural sweet
Blending, color
Dry, table
Dry, table
Dessert
Dry, table
Dry, varietal
Dry, table
Dry, varietal
Dry, table
Dry, table
Dry, table
Dry, table
Dry, table
Dry, table
Dry, table
Dry, varietal
Dry, table
Dry varietal
Dry, table
Blending, color
Dry, table
Dry, varietal
Dessert
Dessert
Dessert
Dessert
Dry, table

* The values assigned are only relative and will vary with environmental conditions. In the right-hand
column, "table" refers to a wine of no particular recognizable varietal characteristic; no other indication of
quality is intended. "Varietal" refers to a wine having a particular flavor or other character recognizable as
having been imparted to the wine by the particular variety of grapes.

t For definition of temperature regions see page 6.

medium-sized; ellipsoidal; black, with
abundant color in the skin; neutral in
flavor, astringent, and high in acid con-
tent. They ripen in midseason. The vines
are vigorous and productive with head
pruning.

The Barbera is best suited to the warm
areas of the coastal valleys and the inter-
mediate central valley region.

Other red-wine grapes. Many of
the world's most important red-wine
grape varieties are not included in the
foregoing descriptions because they are
not grown extensively in California. Very
brief notes on certain of them are given
in table 6.

And these are the

white wine grape varieties

Palomino. In some parts of Califor-
nia the Palomino is erroneously called
Golden Chasselas. It is said to be the prin-
cipal sherry grape of Jerez (Spain).
Widely adaptable to various soils and
climates, it thrives in nearly all warm,
wine-grape-producing districts of the
state. It is particularly well suited to
sherry production, but makes an inferior
dry wine.

The clusters are large medium in size;
shouldered and widely branched; stiffly
loose to well filled. The berries are me-
dium; oblate; greenish yellow, with a
heavy white bloom; and firm to some-
what tough. They ripen in late midsea-
son. The vines are very vigorous and very
productive. The leaves are dull, dark
bluish green in color, rough on the upper
surface, with a heavy, tufted pubescence
on the lower surface. Either head or cor-
don pruning is satisfactory.

The Palomino is particularly well
suited to the San Joaquin, Sacramento,
and intermediate central valley regions.
It also does well in the warm parts of the
coastal valleys, but not in the cool areas.

Burger. Where the soil is fertile and
the climate warm, the Burger produces
enormous crops. In cool locations it does
not ripen well, and early rains may cause
much damage from bunch rot. In the
warmer parts of the coastal valleys, the
berries produce a light wine of fair qual-
ity. In the south coast and the intermedi-
ate central valley regions, the Burger
ripens better and gives heavier yields. Its
primary usefulness is in bulk wines.
When the vines are overcropped, the
grapes are low in acidity.

The clusters are large medium in size ;
shouldered to winged cylindrical; and
compact. The berries are medium-sized;
spherical; whitish yellow; very juicy;
soft; late ripening. The vines are vigor-
ous and highly productive even with head
pruning.

The Burger is best suited to warm loca-
tions in the coastal valleys and to the in-
termediate central valley region.

Sauvignon vert. The origin and true
name of the variety grown in California
under this name is obscure. Its wine has
moderate varietal flavor and aroma, but
is low in acid, is harsh, and does not keep
well. In frosty locations the vines often
bear better than many other varieties.

The clusters are small to medium;
cylindrical; loose to compact. The berries
are small medium; short ellipsoidal;
greenish yellow; soft in texture; juicy;
and thin-skinned. They ripen in midsea-
son. The vines are vigorous, semiupright
in habit of growth, and very productive.

The Sauvignon vert is best suited to
the valleys of the north coast region, but
further planting of this variety is not
recommended.

Semillon. The world-famous Sau-
ternes of France largely owe their char-
acter to the Semillon grape. This variety,
one of the truly fine wine grapes of the
world, does very well in certain parts of

[77]

California. Here, however, because of the
dryness of the climate, the "noble rot"
(Botrytis cinerea) does not work on the
grapes as they ripen; hence the finished
wines differ from the French sauternes in
flavor and aroma.

The clusters are small to medium in
size; short conical; well filled. The ber-
ries are medium-sized; spherical; golden
yellow; sprightly and aromatic in flavor.
They ripen in early midseason. The vines
are vigorous and moderately productive.

The Semillon is best suited to the north
coast region, particularly region 3.

Sauvignon blanc. Next to the Semil-
lon the Sauvignon blanc is the most im-
portant variety of the Sauternes. Used
alone, it makes a fine wine of pronounced
character; but the blend with Semillon
is usually considered superior to the wine
of either variety used alone.

The clusters are small, conical, and

loose. The berries are small; spherical;
whitish yellow; they ripen in early mid-
season. The vines are very vigorous and
require cane pruning.

The Sauvignon blanc is best suited to
the north coast region.

Johannisberger Riesling [White
Riesling), The Rhine wines of Germany
are made principally from the White Ries-
ling. Its wines possess a strong varietal
flavor and bouquet, and the other constit-
uents harmonize.

The clusters are small; cylindrical;
well filled. The berries are small me-
dium in size; spherical; greenish yel-
low, speckled with brown russet dots;
sprightly, somewhat aromatic in flavor;
and juicy. They ripen in early midseason.
The vines are vigorous and moderately
productive with cane pruning.

This variety is suited only to cool areas
of the north coast region.

Table 7
IMPORTANT WHITE-WINE GRAPE VARIETIES NOT EXTENSIVELY
GROWN IN CALIFORNIA

Variety

Boalde Madeira.
Chardonnay. . . .
Chasselas dore . .
Clairette blanche
Feher Szagos . . .
Gray Riesling . . .

Inzolia

Kleinberger

Muscat Canelli . .

Peverella

Pinot blanc

Saint Emilion . . .
Vernaccia Sarda .

Recom-
mended
growing
regionf

4-5

3-4
3-4
2-3

Period of
maturity

Medium

Early

Medium

Late

Medium

Late

Medium

Early

Medium

Early

Late

Medium

Acidity

Medium

Low

Medium

Low

Medium

Low

Medium

High

Medium

Produc-
tivity

High

Low

Medium

High

Very high

High

Medium

Low

Medium

High

Kind of wine
usually produced

Dessert
Dry, varietal
Dry, table
Dry, table
Sherry
Dry, table
Dessert
Dry, table
Dessert, varietal
Dry, table
Dry, varietal
Dry, table
Dessert

* The values assigned are relative only and will vary with environmental conditions. In the right-hand
column, "table" refers to a wine of no particular recognizable varietal characteristic; no other indication of
quality is intended. "Varietal" refers to a wine having a particular flavor or other character recognizable as
having been imparted to the wine by the particular variety of grapes.

t For definition of growing regions, see page 6.

Franken Riesling {Sylvaner). The

Franken Riesling, the principal Rhine-
wine type grown in California, endures
more warmth than the Johannisberger.
The wine is of good character.

The clusters are shouldered conical,
compact; berries greenish yellow; vines
and fruit are susceptible to mildew.

Folle blanche. In white wines requir-
ing a high acid content, such as cham-
pagne, the Folle blanche is particularly
valuable for blending purposes. It also
produces characteristic wines when grown
under favorable conditions.

The clusters are small to medium in
size; conical, shouldered or winged; and
compact. The berries are small medium;
spherical or short ellipsoidal; whitish or
yellowish green; soft; neutral in flavor,
and high in acid. They ripen in midsea-
son. The vines are moderately vigorous
and productive with head pruning.

It is best suited to the warm or moder-
ately cool areas of the coastal valleys.

French Colombard. A combination
of high productivity of the vines and high
acid content of the grapes gives the
French Colombard a. place in the moder-
ately warm areas of the state for produc-
ing standard-quality dry wines. Before
prohibition the French Colombard was
rather widely grown under the name of
West's White Prolific.

The clusters are medium in size; long
conical; well filled. The berries are me-
dium-sized; ellipsoidal; yellowish green,
sometimes with a pink tinge; neutral in
flavor, and high in acid. They ripen in
midseason. The vines are very vigorous
and very productive with head pruning.

The French Colombard is best suited to
the warm areas of the coastal valleys and
the intermediate central valley region.

Other white-wine grapes. Certain
additional varieties of white-wine grapes,
important in other countries but not ex-
tensively grown in California, are given
in table 7.

In order that the information in our publications may be more intelligible it is sometimes neces-
sary to use trade names of products or equipment rather than complicated descriptive or chemical
identifications. In so doing it is unavoidable in some cases that similar products which are on the
market under other trade names may not be cited. No endorsement of named products is intended
nor is criticism implied of similar products which are not mentioned.

CONTENTS

Background information 3

Classes of grapes 3

Basic needs 5

Heat 5

Soil 7

Getting started in business 7

Land clearing 7

Choice of stock 8

Vine spacing 8

Laying out the vineyard 9

Providing support for the vines 12

Pruning 13

Training the vines 19

The first and second years 19

The third year 22

The fourth and later years 23

Cluster, flower, and berry thinning 23

Girdling 25

Cultivation 29

Equipment used 31

Weed control — chemical 33

Soil erosion 33

Contour planting 35

Covercrops 35

Irrigation 36

Amount of water needed 38

When and how to irrigate 39

Fertilizer 42

Propagation of vines 42

Cuttings 42

Budding , 44

Grafting 46

Harvesting 50

Packing and shipping 54

Drying raisins 56

Diseases and pests 57

Varieties 68

Raisin grapes 69

Table grapes 70

Black wine grapes 73

White wine grapes 77

Cooperative Extension work in Agriculture and Home Economics, College of Agriculture,

University of California, and United States Department of Agriculture cooperating.

Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914.

J. Earl Coke, Director, California Agricultural Extension Service.

30m-ll,'50(418)W.P.