UNIVERSITY OF CALIFORNIA
COLLEGE OF AGRICULTURE
AGRICULTURAL EXPERIMENT STATION
BERKELEY, CALIFORNIA
THE ASPARAGUS INDUSTRY
IN CALIFORNIA
H. A. JONES AND W. W. ROBBINS
BULLETIN 446
January, 1928
UNIVERSITY OF CALIFORNIA PRINTING OFFICE
BERKELEY, CALIFORNIA
1928
THE ASPARAGUS INDUSTRY IN CALIFORNIA
H. A. JONESi and W. W. EOBBINS2
INTRODUCTION
Asparagus has always ranked high as a market garden and truck
crop. New Jersey early took the lead, and for many years held first
place in the production of green asparagus. California became the
center of the asparagus industry after the ravages in 1896 of the
asparagus rust in the East.
The first attempt to can asparagus in this country was made by
William H. Hudson, at Hunter's Point, Long Island, in 1864. The
product proved to be popular and the industry grew in New York and
New Jersey. It was not until 1890 that the packing of asparagus in
California became extensive.
There has been a marked increase in the acreage devoted to
asparagus in recent years. Although there is no accurate record
available of the acreage in the different states, it is probably safe to
say that the total acreage in the United States has more than doubled
since 1918.
There has been a steady growth of the asparagus industry in
California since its inception. The centers of production have shifted
somewhat until, today, the three main districts are the Delta, the
Imperial Valley, and the San Fernando Valley.
This bulletin contains material which will be of use to the farmer
who is growing asparagus for the first time ; it also gives the results
of recent experiments and observations conducted by the California
Agricultural Experiment Station; and it summarizes data published
by other investigators which may be of application to California
conditions.
Botanical Relationships and Geographical Distribution. — Asparagus
is a member of the lily family (Liliaceae). A number of the repre-
sentatives of the lily family are cultivated as vegetables, the principal
ones being onions and asparagus. The only species of asparagus
which has been cultivated extensively in the United States as a food
plant is Asparagus officinalis.
A striking characteristic of the genus Asparagus is the slender
green branches, which usually occur in clusters, and from the axils
1 Associate Professor of Truck Crops and Plant Breeder in the Experiment
Station.
2 Associate Professor of Botany and Botanist in the Experiment Station.
4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
of which the flowers arise. These slender branches are known as
cladodes or cladophylls. The true leaves are either scale-like struc-
tures as in A. officinalis, or spine-like as in many of the tropical,
ornamental species.
All species of Asparagus may be propagated by division of the
rootstocks.
Of the common species of Asparagus, A. officinalis is the only one
which grows erect and produces edible shoots. Other common species
are climbing or drooping in their habit. Moreover, in A. officinalis,
the plants are dioecious; that is, male (staminate) and female (pisti-
late) flowers are borne on different individual plants. In the common
climbing or drooping species the flowers are perfect, that is, possess
both stamens and pistils.
The genus Asparagus is distributed from Siberia to South Africa.
The native home of Asparagus officinalis is somewhat more limited,
ranging from Great Britain through Europe to Central Asia. It is
commonly mentioned as a plant of the seashores and riverbanks.
Asparagus has escaped from cultivation wherever it has been
grown. Although not a native of America, it early escaped from
gardens and flourished in the wild state.
THE SEED, SEED GERMINATION, AND DEVELOPMENT OF THE
PLANT THE FIRST SEASON
External Characters of the Seed. — In any lot of asparagus seeds,
it will be observed that there are two distinct shapes, as shown in
figure 1. If two seeds develop in a single cavity of the berry, the
surfaces which touch become flattened because of pressure. However,
if but a single seed develops in a seed cavity, it becomes equally
rounded on all sides. There is no reason to believe that either one of
these types of seed is superior to the other.
There is considerable variation in the weight of asparagus seed
among different varieties. Seed obtained from different sources may
vary considerably in size owing to different methods of screening.
The seed of the Martha Washington strain is smaller, and that of
the Mary Washington is somewhat larger, than the seed of most other
varieties.
There is found a pronounced difference in the glossiness of the
seed coats of various lots of seed. Some are shiny black, whereas others
are a dull color. It is believed that dullness is due at least in part to
the age of the seed. In different lots of seed, there is considerable
variation in the amount of fruit wall (pericarp) which is attached to
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
the seed. This appears as a thin, white papery coating. Incomplete
threshing and washing are responsible for the presence of these
membranes.
**SI
&
a
: r4
Fig. 1. — Two shapes of asparagus seeds (top view). Left, rounded seed from
loeule which bcre but this one seed ; right, seed flattened on one side, from locule
which produced two seeds. (From Bul. 381.)
..seed coat
Fig. 2. — Diagrams of asparagus seeds showing position of the embryo.
A, section through the seed showing the embryo in longitudinal section. B, section
through the seed showing the embryo in transverse section. (From Bul. 381.)
6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Internal Structure. — The asparagus seed has three essential parts
(fig. 2) : (1) the seed coat; (2) the embryo plant or germ; (3) the
endosperm or reserve food.
Figure 3 shows a section of the mature seed coat. In the develop-
ment of the seed coat there has been a progressive desiccation and
shrinkage of the cells, with a consequent decrease in the thickness of
this coat, The outer wall of the single, epidermal layer of cells
becomes very thick, and the lumina become almost completely filled
\ endosperm
Fig. 3. — Section of a portion of an asparagus seed, showing the seed coat
and the large cells of the endosperm, with thick walls of hemicellulose ("reserve
cellulose"), and cell cavities filled with oil globules and protein granules.
(Treated 18 hours with 2 per cent sodium hydroxide solution in order to swell
the cells of the seed coat.) Illustration from Bui. 381.
with a dark, brown granular material. Beneath this epidermal layer
are the very much compressed and dried remains of integumentary
cells. Beneath these is a suberized membrane, separable into a broad
membrane and a narrow one closely compressed. These represent
respectively the "cuticles" of the inner and outer integuments. This
double membrane plays a very important part in the absorption
processes carried on by the seed, preventing, either totally or in part,
the entrance of certain salts and other substances, although it does
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 7
not inhibit the movement of water through it. The bulk of the seed
is composed of endosperm cells, which contain food reserves.
The embryo is a very small, slender body, simple in structure and
somewhat curved at one end (fig. 2). At one end of the embryo is the
root tip. A short distance behind the root tip is a shallow depression,
at the base of which is the growing point, The remainder of the
embryo, and by far the largest part, is an absorptive organ. This
organ, the cotyledon, remains in contact with the endosperm during
the early stages of germination, absorbs food from the endosperm and
delivers it to the growing regions.
The embryo is completely surrounded by the endosperm. Most
endosperm cells have thick pitted walls of hemicellulose, and lumina
well filled with fat globules and protein granules.
The hard, flinty endosperm constitutes a reserve food supply.
There are two chief kinds of food stored in the endosperm of
asparagus. These are hemicellulose and fat. Protein is relatively
less abundant as a storage product. Hemicellulose is a carbohydrate
somewhat resembling starch and ordinary cellulose in its chemical
composition. Hemicellulose is stored in the walls of the endosperm
cells ; fat occurs as droplets in the cell cavities. The hardness of the
endosperm of the asparagus seed is due to hemicellulose in its walls.
Seed Storage. — There are many conditions which affect the vitality
of seeds. In a ripe seed, the essential part, the living embryo, or
young plant is in a relatively inactive state. The conditions under
which seeds are stored should be such as to keep it inactive. The
temperature should be kept fairly low and uniform, and the atmos-
pheric humidity low. If seeds are not stored in a dry place, the
moisture present may be sufficient, provided there is the proper tem-
perature and oxygen supply, to start germination. If germination
processes are started, it follows that the respiration rate increases,
with a consequent loss of dry weight and a decrease in the amount of
stored food and therefore of stored energy in the seeds. Seeds stored
in bulk under such conditions may "heat." This may be due in part
to heat liberated by the respiration of the seeds themselves and in
part to the heat of respiration of fungi and bacteria growing on the
seeds. The heat thus developed may become so intense as actually to
kill the embryos. Under the best storage conditions, asparagus seed
should remain viable for a period of from five to seven years. It is
always best to make a germination test on asparagus seed before
planting to determine the percentage of viable seeds, so that the
seeding rate can be accurately ascertained.
8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Conditions Necessary for Germination. — The requirements for the
germination of asparagus seed, and in fact of all seeds, are water,
oxygen, and a proper temperature. In certain experiments, asparagus
seeds have been kept in water for three months without showing
evidence of germination, and this prolonged soaking in water at
ordinary temperatures does no apparent injury to the seeds, for when
they are removed from the water and placed under conditions suitable
for germination, sprouts appear within a few days and the percentage
of germination is normal. Asparagus seeds submerged in water are
under a condition of low oxygen supply, but they may be made to
germinate within four or five days if the water is aerated by bubbling
air through it. The above experiments point to the conclusion that
asparagus seed will endure long soaking in water at ordinary tem-
peratures. However, germination of the seed will not result unless
there is a plentiful supply of oxygen, such as occurs in a soil in good
physical condition.
The optimum temperature for the germination of asparagus seed
is between 77° and 86° F. At 68° F, germination is very slow.
Germination of asparagus seed will be slow if sown in a soil the
temperature of which is 68° F or below. The absorption of water by
the seed at temperatures below 77° F is very slow.
Rate of Germination. — The rate of germination of asparagus seed
depends upon water and oxygen supply and upon the soil tempera-
ture. With all conditions near the optimum, the root breaks through
the seed coat within 6 to 8 days after planting ; within 10 or 12 days
the first shoot appears. The time required for the shoot to reach the
surface of the soil depends not only upon the supply of water and
oxygen, and upon the temperature, but also upon the depth of plant-
ing and texture of the soil. The sooner the shoot reaches the light,
becomes green, and begins to manufacture its own food, the greater
are its chances of survival. If, however, the developing seedling must
struggle through an excessive depth of soil or one in poor physical
condition, it may exhaust its food supply and succumb before reaching
the surface.
Hastening the Germination of Asparagus Seed. — Borthwick (3) has
shown that it is possible to hasten the germination of asparagus seed
by soaking it in water. Both laboratory and field data show that
soaked seeds germinate more quickly than unsoaked seeds, even though
planted in cold soil. For practical purposes, a period of 3 to 5 days'
soaking at a temperature of 86° to 95° F is recommended.
The Germination Processes and Stages in the Development of the
S<<<H'ni<i. — The first process in the germination of any seed is the
BuL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 9
absorption of water, which softens the coats and swells the seed. The
cell walls become filled with water, in which condition they permit the
more ready intake of oxygen and outgo of carbon dioxide. At 86° F
asparagus seed absorbs the maximum amount of water (approxi-
mately 43 per cent) in about 48 hours, if immersed. As soon as the
contents of the endosperm cells are sufficiently diluted, the various
enzymes which digest food are secreted. It will be recalled that the
principal reserve foods in the endosperm of the asparagus seed are
fat, protein, and hemicellulose. Gradually, the thick walls of hemi-
cellulose become thinner ; this material is slowly digested, that is,
changed to sugars, which are soluble. The proteins and fats are also
digested, and the products of digestion are transferred to the growing
points of the embryo. At these growing points, soluble foods are
being transformed into cellulose walls and into living material. This
transformation is called assimilation. All living cells of the germi-
nating seeds are respiring. And since the cells are very active, the
process of respiration is correspondingly active.
It has been observed that the embryo is completely surrounded by
the endosperm (fig. 2). The cotyledon absorbs food from the sur-
rounding endosperm cells and transfers this food to the growing
points of the embryo. As germination proceeds, the endosperm cells
immediately adjacent to the cotyledon are the first to show indications
of disintegration due to the digestion of their contents and walls.
The cotyledon enlarges (fig. 4), gradually encroaching upon the
endosperm, until finally almost all of its reserve food is absorbed.
The developing embryo, by means of the cotyledon, maintains con-
nection with the endosperm for a period of three or four weeks.
After the young plant has developed a primary root and a leafy
shoot, the cotyledon and the undigested endosperm cells, if any,
wither and become disconnected from the seedling. It is possible to
observe on seedlings many weeks old, the scar marking the point
where the cotyledon was attached.
The root is the first structure of the embryo to break through the
seed coat (fig. 4). Shortly after the root protrudes, root hairs begin
to form at a point from 2 to 4 millimeters back of the root tip. The
root apparently breaks its way through the seed coat simply by
pressure.
When the primary root has attained a length of 6 to 10 millimeters
a "hump" or elevation may be observed just posterior to the root
hair zone (fig. 4). Careful examination reveals here a slit or opening,
through which the primary shoot emerges.
10
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
In the growth of the seedling, the single primary root takes a
direct course downward, developing numerous thread-like lateral
rootlets. Its chief function is absorption. It seldom attains a length
of more than 5 or 6 inches. It is much more slender and fibrous than
the storage roots which develop later. The single primary shoot
cofy/edon
an obsorbing o/yon
Fig. 4. — Early stages in the development of the asparagus seedling.
A, 7 days; B, 10 days; C, 12 days; and D, 18 days after planting of seed.
takes a direct course upward, and upon reaching the light develops
a few side branches and leaves. The primary root and primary shoot
attain a length of 3 or 4 inches before connection with the reserve
supply of food in the seed is severed. The primary root and the
primary shoot are temporary organs. They wither and die long
before the end of the first growing season.
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
11
Fig. 5. — Five stages in the development of an asparagus seedling. At the left
a very young stage showing the short primary root and the much shorter primary
shoot, both of which are attached to the seed and are deriving nourishment
from the stored food in the endosperm. In the second and third stages the
seed is still attached. In the fourth stage the plant has become independent of
stored food in the seed, the primary shoot has branched slightly, a second shoot
has arisen from the crown, and a fleshy root has developed. In the fifth stage
there is shown the primary shoot, two well developed secondary shoots and
one very short secondary shoot. The following are the dates of digging and
the ages of the different seedlings: (1) April 3, 10 days after planting the seed;
(2) April 7, 14 days after planting the seed; (3) April 27, 34 days after planting
the seed; (4) May 19, 54 days after planting the seed; (5) June 9, 75 days
after planting the seed. (From Bul. 381.)
12
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Fig. 6. — Asparagus plant taken from the nursery August 13, 100 days after
planting the seed. Note the first flower-bearing stalk (center). The primary
root has become detached and the primary shoot has withered. This plant
shows very strikingly the increase in height and diameter of the shoots as they
make their appearance consecutively throughout the season. (From Bui. 381.)
BUL. 446] TIJE ASPARAGUS INDUSTRY IN CALIFORNIA 13
Throughout the first season of growth there is a rapid increase
in the number of secondary shoots.
Each new shoot which arises on the crown during the first year is
almost always larger than the one preceding (figs. 5 and 6). The
larger size of the new shoots which appear successively on the
lengthening rootstock is probably due to the rapid increase in the
supply of food.
The rate of development of the asparagus plant in the nursery
depends much upon the soil conditions, particularly upon the avail-
able water supply. Deficiency in the available water is readily
reflected in retarded growth of the plants. By the last of June the
roots have penetrated the soil to a depth of 7 inches or more, and by
the last of July they have reached levels as deep as 18 inches.
Sex Expression in the Nursery. — Under California conditions
asparagus usually comes into flower during the first season of growth
from the seed. It is often possible, however, even in the nursery
before the flowers appear, to distinguish male from female plants.
The latter are taller, as a rule, than the male plants, but the number
of shoots to the plant may be fewer. Male plants bloom earlier in
the season than female plants. Considering the population as a whole
early in the season, the male individuals constitute a majority of all
plants in bloom.
THE ROOTS
The Root System. — As previously stated, the primary root is a
temporary structure. Within two or three weeks after it has protruded
from the seed, the first secondary root makes its appearance. It
originates at a point on the rootstock at the base of the first secondary
shoot (fig. 10). As compared with the primary root, the secondary
ones are of much greater diameter. They are fleshy, cylindrical roots,
of rather uniform diameter throughout their entire length. They are
usually devoid of any lateral roots for a considerable distance from
their tips ; often the first laterals are from 8 to 10 inches from the tip.
The lateral roots, borne by the thick fleshy ones, are slender and
fibrous.
It has been customary to speak of the large fleshy roots of
asparagus as " storage roots," and of the fibrous ones as "absorptive
roots. ' ' The understanding has been that the fleshy roots are storage
organs exclusively, whereas the fibrous laterals arising from them
have purely an absorptive function. From the description which
follows under root structure, it will be seen that the surface of young
fleshy roots is thickly covered with functioning root hairs, and hence,
14
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
mm
Fig. 7. — Asparagus plant showing top growth, crown, and mass of fleshy
roots. Crown set in field, 1919; photo taken July 25, 1924.
Bul. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 15
these roots serve not only as storage but as absorptive organs as well.
The fibrous roots, on the other hand, appear to be almost exclusively
absorptive structures.
The root system of asparagus has the general form of a cone, with
the apex toward the ground line (fig. 7). Numerous roots take a
rather direct course downward, though the more usual direction is
obliquely downward. However, a great number of the long, fleshy
roots, particularly those arising from the older and more deep-seated
part of the rootstock, may take an almost horizontal course in the soil,
and even trend upwards for a long distance.
^ffip
Fig. 8. — Tip of fleshy root of asparagus. The uninjured tips of old roots
continue to grow the succeeding seasons. In this, parts of two season's growth
are shown. Note the shreds of cortex torn back at the point where new root
growth begins.
The fleshy roots arise from the lower surface of the rootstock. As
the branches of the rootstock grow in length, fleshy roots are being
continually formed near the tip. As new aerial shoots are sent forth,
associated with them are new fleshy roots. In point of time, buds
precede in their development the roots with which they are associated.
Hence, one may always expect to find the most active roots at the
extremities of the branches which make up the rootstock.
Growth in Length and Duration of Fleshy Boots. — Fleshy roots
continue to grow at the tip for several years unless the tips are
injured. The following record is of a typical fleshy root on a six-
year-old asparagus crown, grown in a sandy loam soil at University
Farm, Davis, California. The root had a total length of approxi-
mately 11 feet. This root showed three definite scars along its
length, each indicating the point where one year's growth ceased and
that of the following year began. The root was at least four years
old, possibly older, but evidence of greater age could not be found.
Successive years' growth may be distinguished by the color and texture
of the cortex (fig. 8). When growth of the root tip is resumed in the
spring, the protective cortical tissue which covers the tip is ruptured
and its shredded margin remains for a period, thus marking the
16
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Pig. 5). — A vigorous " Number 1" asparagus crown, taken during the second
season of growth. Note the injured root tips, which have made no further
growth. Root tips which are uninjured in digging continue growth. The fresh
white story ge roots, from which yrise numerous absorbing roots, stand out in
contrast with the older and darker storage roots which bear fewer absorbing
roots. At points marked "a" in the photograph, there can be seen the line of
demarcation between two successive years' growth of a storage root. (From
Bui. 381.)
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
17
termination and beginning of two successive years' growth. The
distinction between successive years' growth is not very evident in the
older parts of the root.
In the digging of one-year-old crowns for transplanting, care
should be taken that the fleshy roots be obtained with as little injury
to them as possible. If the growing point of a fleshy root is not
injured, it will continue to elongate after planting. Storage roots
that have not been badly crushed or injured, even though the tips
ma} 7 have been destroyed, may develop an abundance of lateral
absorptive roots. When these habits of root growth are considered,
together with the fact that the bulk of the stored food in asparagus
is in the fleshy roots, the importance of preserving as many of them
as possible in transplanting should be kept in mind.
Fleshy and Fibrous Roots. — Under California conditions at least,
the individual fleshy roots function for a period of at least three years,
possibly longer. The fibrous ones, on the other hand, function for a
single season, and then die, a new "crop" being developed each season.
These new fibrous roots may arise on the older as well as on the younger
parts of the fleshy roots. Loisel, (14) describing the root system of
asparagus grown under the conditions prevailing in France, says that
as new fleshy roots are formed the older ones die, so that a plant is
always young; the oldest roots are only three years. He states that
the two-year-old roots have already lost in part their vegetative
function, and in reality the one-year-old roots are the only ones that
supply the plant with a large amount of food.
Extent of the Boot System. — The extent of the fleshy root system
of asparagus plants of different ages is shown in table 1. The plants
grew in a peat soil typical of the Delta region of California, An
effort was made in digging to secure as much of each fleshy root as
possible, but it is estimated that fully one-half of the total length of
fleshy roots was left in the soil. The roots extended to a maximum
depth of 7 feet.
TABLE l
Number and Total Length of Fleshy Boots in Asparagus
Age of
set crown,
years
Number
of roots
Total measured
length of roots
(feet)
Estimated total
length of roots
(feet)
1
252
379
758
3
396
724
1,448
4
596
1,399
2,798
5
1,178
2,060
4,120
6
1,012
1,707
3,414
18
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
It will be seen from these data, that the root system of an
asparagus plant, as old as six years, is very extensive. The depth to
which they penetrate is dependent to a large degree upon the depth
of the permanent water table.
In addition to absorption, the roots of asparagus function as con-
ducting organs, as anchorage organs, and in the case of the fleshy
roots, as storage organs. The edible shoots that arise in spring are
probably made almost entirely from reserve food in the fleshy roots.
first secondary
/shoot
Fig. 10. — Stages in the development of the seedling. A, April 27, the young
plant is still attached to the seed. The primary shoot and primary root have
developed, and the beginnings of the first secondary root are seen (dotted).
B, May 19, with primary shoot (a), first secondary shoot (1), primary root and
first secondary root and buds. C, June 9, as seen in section. B, June 30, show-
ing three secondary shoots (1, 2, 3, 4). E, diagram of D showing relative
positions of new shoots.
THE STEMS AND LEAVES
The Rootstock (Underground Stem). — The body of the rootstock
of asparagus is a structure compounded of parts of a number of
lateral shoots (branches).
The progressive development of the rootstock is shown in the series
of drawings (figs. 10 to 12). In figure 11, observe that the main
direction of growth of the rhizome is on the side of the primary axis
opposite the point of its attachment to the cotyledon (absorbing
organ). Aerial shoot 1 arose as a lateral branch from the base of a;
aerial shoot 2 as a lateral branch from shoot 1 : from the base of shoot
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
19
2, there were two lateral shoots developed, of which No. 3 became an
aerial shoot, and 2a, a side shoot. A number of the lateral buds which
arise at the base of an erect shoot remain dormant for a long or short
period. These dormant shoots or "buds" are evident on the root-
pnmary
shoot
seed coat-
primary^ root
Fig. 11. — Stage in the development of the asparagus crown the first season
from seed. Note the shrivelled seed coat. Shoots 1-8 belong to the main axis;
2a-2~b, and 4a^-4b, are lateral branches.
stock ; each occurs at the base of an aerial shoot. A rootstock five or
six years old may bear a hundred or more dormant "buds." (fig. 13) ^
Since each shoot is a lateral arising from the base of the preced-
ing, its point of origin is slightly above that of its predecessor. Thus
20 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
there is a gradual elevation of the rootstock. The rate of elevation
depends upon the original depth at which the crown was planted.
For example, in figure 14 is shown a rootstock all branches of which
grew almost vertical. The one-year-old crown of this plant was
planted at a depth of about 20 inches. In figure 15 there is illustrated
Fig. 12. — Stage in the development of the crown. August 13.
a crown the rootstock of which has grown upward at a relatively slow
rate from year to year. This crown was planted to the usual depth
of about 10 inches.
In a very old plant the upper part of the rootstock may be exposed
and the new shoots may arise at or very near the soil surface. As the
Bul. 446 J THE ASPARAGUS INDUSTRY IN CALIFORNIA
21
Fig. 13. — Detail of a lateral branch of asparagus crown, which has been
stripped of roots. Note the lateral buds along the full length of the branch.
Crown set 1919; photo taken August 20, 1924.
Fig. 14. — Asparagus crowns showing the manner of growth resulting from
deep planting of the crown. The crowns were planted at a depth of 18 inches;
as a result the branches grew almost vertically upward. Crowns six years old.
The crown on the left shows the appearance before the roots were removed.
22
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
rootstock ages, the lower and oldest portion of it may decompose, so
that there is a tendency for it to become divided into several distinct
parts.
The rootstock proper is a woody structure, possessing innumerable
vascular strands which cross and re-cross each other. It is mainly a
conducting structure, only a small amount of food being stored therein.
Fig. 15. — Portion of a crown of asparagus, showing a lateral branch.
Note the tendency to grow toward the surface of the ground.
The Aerial Shoots. — The aerial shoots arise from the rootstock.
These shoots when young constitute the edible spears for which
asparagus is grown.
The main shoots are rapidly growing structures, the rate of growth
depending chiefly upon the temperature.
Working ( 26 » 27) has shown that "light has little or no immediate
effect on the growth rate of young shoots or seedlings, or the height
they attain before branching. Its effect is chiefly through the food
stored from previous photosynthesis." He further states that "the
three external factors of greatest importance in the growth rate of
the young shoot are the temperature, the moisture of the soil, and the
salt balance of the soil."
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
23
Factors Influencing the Size of the Spear. — The size of the
harvested asparagus shoot or spear depends upon the following :
(1) heredity, (2) age of the plant, (3) sex of the plant, (4) j)oint of
origin of the shoot on the rootstock, (5) food reserve in the rootstock
and fleshy roots, (6) soil fertility, and (7) moisture.
Heredity. — There is a fairly constant difference between certain
varieties of asparagus as to the average size of the edible shoots. For
example, under similar growth conditions the Mary Washington
variety usually produces spears that are larger than that of the
common varieties grown in this country. The breeding work with
asparagus has demonstrated that size of stalk is an heritable quality.
Fig. 16. — Five different ages of asparagus crowns showing the growth made
each year. Photo taken July 25, 1924. Crowns set in field in 1918, 1919, 1920,
1921, and 1923.
Age of Plant. — After the tenth or eleventh year, or even earlier,
there is, as a rule, a noticeable decrease in the size of spears. It is a
common observation that old asparagus beds produce "spindling"
shoots.
Sex of Plant. — Shoots from female plants are larger on the average
than those from male plants. This fact is well shown by data
presented in table 3.
These data show that male plants produce more spears and a
greater total weight of spears per crown than female plants. Male
plants, as compared with female plants, have a tendency to produce a
larger number of relatively smaller shoots.
Tiedjens (23) found that staminate plants have more buds than
pistillate plants. For example, for a four-year period, the average
24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
bud production for the staminate plants was 23, 24, 21, and 24 respec-
tively. Teidjens undoubtedly refers to terminal buds. He points out
that the majority of buds are formed the season previous to their
appearance as spears, but that in many cases the first buds formed
during the growing season may produce stalks the same year.
Point of Origin of the Shoot on the Rootstock. — The largest shoots
on an asparagus crown usually arise at the extremities of the main
branches of the rootstock. The smaller, spindling shoots arise from
lateral branches of the main rootstock, and usually appear near the
older part of the crown. They are frequently from buds that have
been dormant for a number of years.
Food Reserve in the Crowns. — The shoots formed early in the
season, at a time when there is a maximum food reserve in the roots,
are larger than those which appear late in the harvest season. This
decrease in size, as the season progresses, is probably due at least in
part to a diminishing food supply.
A study of the composition of the roots and rootstock at the begin-
ning and at the close of the harvest season shows that the production
of aerial shoots is a drain upon the food reserves in these underground
structures.
Soil Fertility. — Size of spears, as well as the number of spears, is
influenced by the fertility of the soil.
Moisture Supply. — The asparagus plant is very responsive to the
supply of water. A deficiency of water results in small spears.
Gross Structure of the Shoot. — The edible asparagus shoot is a
roughly cylindrical structure, usually slightly oval in cross-section,
and bears a number of leaves at the nodes (fig. 17). The shape of the
tip of the shoot is often mentioned as a variety characteristic. A
lengthwise, median section of the tip shows a terminal growing point ;
from the nodes of this very much shortened axis may be seen the
primordia of side branches, and even of flowers. The tight tip is
desirable from the standpoint of the canner and shipper. By this is
meant a tip in which the scale leaves are closely compressed and
firmly overlapping, so that no branch and flower primordia can be
observed. In the open tip the scale leaves are spread outward, the
branch and flower primordia are more or less in evidence, and the
entire tip has an open appearance. It is even possible in asparagus
shoots, in which the tips are open, to dissect the immature flowers,
and find the basal ones so far advanced that their sex may be deter-
mined. The height at which the branching begins is a variable
character. Some plants branch low, others relatively high. The latter
Bul. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 25
type is more desirable, because the tip is more tightly closed, and
therefore a longer green shoot of desirable type can be harvested.
High branching is characteristic of the Mary Washington variety.
The tendency of the plant to branch low or high may be discerned
even in the seedling stage.
It appears from the experiments of Working (27) that temperature
is the chief external factor determining the branching of young shoots.
Neither light nor the depletion of the reserve food material in the
Fig. 17. — An undesirable (left), and a desirable type of spear.
roots have any influence. In his experiments, shoots in the light
growing at a temperature of 95° to 105° P began to branch when
only 6 to 8 centimeters long, whereas at a temperature of 59° F they
attained a height of 75 to 100 centimeters.
Cladophylls. — The needle-like stems of asparagus, known as
1 ! cladophylls, " are the principal food manufacturing organs of the
plant. They usually occur in clusters.
Scale Leaves. — The scale leaves are thin, membranous structures,
which always arise at the nodes. They are pointed at the tip and
bear a characteristic downwardly directed lobe.
The true leaves ("scales") of asparagus constitute a very small
portion of the plant surface. Although they may contain chlorophyll
26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
for a time and thus be capable of manufacturing small amounts of
food, they soon become dry and parchment-like.
The chlorophyll pigment is formed in the shoots shortly after they
appear above ground. A portion of the food manufactured in the
green tissue of the plant is utilized immediately in the growth of
shoots. The surplus produced during the growing season, however,
is stored in the fleshy roots.
The Functions of the Stems. — The principal functions of the leaves
of most plants are food manufacture and transpiration (loss of
water). In asparagus these functions take place almost entirely in
the cladophylls and larger stems. In asparagus, aboveground stems
of all orders possess chlorophyll.
THE FLOWERS, FRUIT, AND SEED
The Flowers. — The flowers occur in the axils of scale leaves and
are associated with ordinary vegetative branches, with " needles' '
(cladophylls), or with both. The branches of the first, second, and
third order usually have with them, that is, arising from the same
leaf axil, two flowers, although there may be none at all, or as many
as four or five at the extremities of the plant. Clusters of needles
only may arise at a node.
The flowers of asparagus are of the liliaceous type ; they are
radially symmetrical; the ovary is superior; the perianth lobes are
separate; they occur in two distinct whorls of three each, and the
segments are similar in color and texture; there are six stamens, in
two whorls of three each; and there is a single pistil, the ovary of
which has three cells or locules.
Asparagus is dioecious, that is, has two kinds of flowers, staminate
and pistillate, but only one kind on a plant. Rarely, perfect flowers
occur.
The Pistillate Flower. — The pistillate flower is smaller and is less
elongated than the staminate flower. These differences are shown in
figures 18 and 19.
There are six rudimentary stamens. The ovary of the pistil is
distinctly three-lobed, and in cross-section is seen to have three locules
or ovule cavities and normally six ovules attached to a central axis.
The style is short and is more or less distinctly three-grooved. The
stigma is three-lobed; its surface is papillate, which enables it to
catch and retain the pollen grains.
There are three stylar canals which extend from the stigma to the
cavity of the ovary. The pollen tubes grow along the sides of these
canals and thus reach the ovules.
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA
27
Fig. 18. — Stages in the development of the pistillate (female) flower and
berry, lettered in the order of their development. Observe the rudimentary
stamens, s, rudimentary stamen; p, pistil.
28
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
The Staminate Flower. — The perianth segments are as described
in the pistillate flower. There are six well-developed, functioning
stamens. The pistil is rudimentary (fig. 19).
Development of the Flowers. — : The first evidence of the flower is
a slight rounded protuberance in the axil of a scale leaf. The early
stages of development of staminate and pistillate flowers are similar.
Fig. 19.— Stages in the development of the staminate (male) flower. Observe
the rudimentary pistil, s, stamen; p, rudimentary pistil.
In young staminate flowers, the pistil may have a shape typical of
that of pistillate flowers of the same age, but it fails to attain normal
size ; the absence, or very weak development, of the style and stigma
is characteristic of staminate flowers ; it may have locules in the ovary,
and ovules may begin development, but they fail to reach maturity.
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
29
In young- pistillate flowers, the stamens may develop as those in the
staminate flowers for a time, but subsequently the anthers fail to
attain normal size, the filaments are short, and there is a disintegration
of potential pollen-mother cells. This is followed by a shrivelling of
the entire anther.
The development of the anthers presents no features peculiar to
asparagus. The ovules arise from the tissue on the central axis of
the ovary.
The pistil of the staminate flower varies somewhat as to the stage
of development it attains. Usually, it is smaller than in a normal
pistillate flower and the style and stigma may be absent or very much
reduced in size. The ovules of staminate flowers usually do not
develop further than the primary archesporial stage. The integuments
seldom attain a size sufficient to enclose the ovule. Disorganization
of the ovule begins before the anther of the same flower has shed its
pollen.
After fertilization, changes take place in all parts of the ovule
and ovary.
The Fruit. — The young, immature fruit is green in color. As it
matures, it assumes a red color. The mature fruit is spherical. The
perianth segments and the peduncle adhere to its base. At the tip is a
small point, the remnant of the style. The fruit wall, the central
axis, and the walls separating the locules (seed cavities), are some-
what fleshy. There are three distinct layers of the ovary wall; the
exocarp, the mesocarp, and the endocarp. The exocarp consists of a
single layer of cells, the outer wall of which is much thickened. The
mesocarp is composed of many rows of large cells. It is in these that
the chloroplasts, and later the chromoplasts, occur. The endocarp
contains several rows of cells, and in the mature berry it forms a thin,
parchment-like membrane which often adheres to the seeds.
The asparagus berry usually has three seed cavities. As a rule
two seeds begin to develop in each cavity of the ovary. However,
they do not always all reach maturity. Fruits with different numbers
of seeds occurred with a frequency shown in table 2.
Number, of
TABLE 2
Seeds to the Berry
Number of seeds to the berry
i
2
3
4
5
6
7
8
Total
Number of berries
Per cent of the total
number of berries
86
6,3
83
6.1
185
13.8
265
19.7
362
26.8
365
27.2
3
0.2
1
0.1
1,350
100
30 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
From this it will be seen that there is approximately an equal
percentage of berries containing five or six seeds, respectively, and
considering all the classes, the total percentage of berries having
fewer than six seeds is much greater (72.7 per cent) than that having
six seeds to the berry (27.0 per cent).
One frequently finds plants bearing a number of berries which
redden prematurely, are much undersized, and contain no viable seed.
They are conspicuous on account of their bright orange color in
contrast to the green of the normal immature berries. The pedicel
has a normal length. The ovary wall and partitions separating the
locules are fleshy, and orange in color. The ovule coats are only
partially developed. The orange color extends throughout all tissues
of the pericarp, and includes the partition walls and placentae.
THE SEX OF ASPARAGUS
Male and Female Plants. — As has been stated, in asparagus there
are two kinds of plants, as to sex : male or staminate plants and female
or pistillate plants. Normally, all the flowers on any one plant are
staminate or pollen-bearing, or all of them are pistillate or seed-bear-
ing. Occasionally, however, hermaphroditic or perfect flowers are
found. Such flowers bear both stamens and pistil that are functional.
Sex Intergrades. — In asparagus the following kinds of flowers
have been observed : strongly pistillate, weakly pistillate, hermaphro-
ditic, weakly staminate, strongly staminate.
In " strongly pistillate" flowers, the ovary is well developed, the
style is long, and the stigmatic surface plainly visible; the stamens
are represented by the merest traces of atrophied tissue. In "weakly
pistillate" flowers the ovary is somewhat smaller than in the preced-
ing case, the style is short, and the stigmatic surface is not so well
defined ; the form of the anthers may be observed, although no pollen
is produced and the anthers soon wither. In hermaphroditic flowers
both pollen-bearing anthers and ovule-bearing pistils are developed.
Only a very small percentage of true hermaphroditic flowers have
been observed among the hundreds of flowers which have been
examined in California asparagus fields. In "weakly staminate"
flowers the stamens are short, but functional, and the ovaries are
large and bear a short style but are not-ovule bearing. In " strongly
staminate" flowers stamens are well developed and normal in size,
the pollen grains are functional, but the only evidence of the pistil is
a very small conical body, without a style, in the center of the flower.
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 31
Sex Ratio in the Fields. — The ratio of staminate and pistillate
plants in commercial fields (California) was determined by walking
down the asparagus rows and recording the sex of each consecutive
plant. The data show that there are approximately equal numbers
of staminate and pistillate individuals.
Expression of Sex of Seedling Plants. — In the eastern United
States asparagus plants seldom bloom until the second year from seed,
but in California a considerable number of plants flower the first year.
Field studies show that there is a tendency for staminate plants to
express their sex much earlier in life than pistillate plants. Many
plants do not flower the first season, but of those that do, by far the
larger percentage is staminate.
Comparison of Staminate and Pistillate Seedling Plants. — Each
new shoot which arises on the crown during the first year from seed
is usually larger than the preceding. The first four secondary shoots,
so far as observed, were never flower-bearing, but in some few indi-
viduals, the fifth secondary shoot did produce flowers. In staminate
plants, the first flower-bearing shoot varied from the fifth to the
eleventh (average, 7.2 for the 149 plants observed) ; in pistillate
plants, the first flower-bearing shoot varied from the fifth to the
fourteenth (average, 8.5 for the 80 plants observed). These data
were taken from August 8 to 11. on the Palmetto variety. Thus it is
seen that the first flower-bearing shoot usually appears earlier in the
life of the staminate than in the pistillate plant. Measurements taken
on the two groups of plants show that the average height of the first
flower-bearing shoot of staminate plants is 47.8 centimeters, whereas
the average height of the first flower-bearing shoot of pistillate plants
is 62.4 centimeters, a difference in height of 14.6 in favor of the
pistillate stalks.
Top Growth of Staminate and Pistillate Plants the Year Crowns
Are Set. — In a comparison of top growth made by staminate and
pistillate plants the year the crowns are set it was shown that
staminate plants produce a larger number of stalks, but that there
is no significant difference between the sexes as to average height of
the stalk and the average green weight of tops if the berries are not
removed. The berries comprise a large percentage of the weight of
the pistillate plants, although the weight of these was not determined
separately the first year. If the weight of berries is subtracted from
the green weight of tops it appears that the food-manufacturing
surface of staminate plants exceeds that of the pistillate. One might
expect, then, a greater quantity" of reserve food stored in crowns of
32 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION
staminate than in those of pistillate plants, and that the yield of
shoots the following season would be higher.
Yield of Spears from Staminate and Pistillate Plants. — A number
of workers have noted that staminate asparagus plants outyield the
pistillate. Among these are Green (11) who in comparing 50 plants
each of staminate and pistillate found a gain of about 50 per cent for
the staminate plants over the pistillate plants during the whole season.
The yield of staminate as compared with pistillate plants was pro-
portionately greater during the early part of the cutting season than
during the late. Tompson, at the Massachusetts Agricultural Experi-
ment Station, using the Washington strain of asparagus, reports
experiments which show that staminate plants produce the larger
number of spears, but that the proportion of " giant" asparagus is
much greater from the pistillate plants. This held consistently true
throughout the whole population, which was over 1,000 plants. In a
later report Tiedjens (23) states that "Staminate plants are higher
producing by 25 per cent, and hold up better from year to year
Pistillate plants produce a greater percentage of "A" (large) spears."
B6ttner, (4) after pointing out the superiority of male as compared with
female plants, states that it is a common observation that in old
asparagus beds the gaps that appear here and there in the rows are
due to the death of female plants. Whereas in the young plantation
there are equal numbers of staminate and pistillate plants, in old
plantations there is a predominance of staminate individuals. He
describes a method, known as the "Bottner System," whereby only
staminate plants are employed in the plantation.
In 1923, an extensive experiment was started at the University
Farm, Davis, California, the object of which is to test the performance
of staminate and pistillate plants over a series of years. In that year,
a large number of pistillate and staminate plants were labelled in the
nursery. The seed was planted February 28 and March 8. By Sep-
tember 3, 31 per cent of the plants in the nursery had come into
bloom, and by the end of the season approximately 58 per cent of the
plants had expressed their sex.
These staminate and pistillate crowns were planted early in 1924
in separate rows in the permanent bed. The rows are 240 feet long
and the distance between rows 7.5 feet. Staminate and pistillate rows
were placed side by side.
From this planting, a record of the top growth made in 1924, 1925,
and 1926, and of spear production in 1925 and 1926 are shown in
table 3.
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
33
TABLE 3
A Comparison of the Performance of Staminate and Pistillate
Asparagus Plants (Crowns set 1924)
Staminate
Pistillate
1.
Top growth, 1924:
Average number stalks per plant (Nov. 8)
8.51
0.78
2.98
55.87
18.74
8.40
2.65
15.68
372.75
23.77
2555.97
8.43
2.90
5 70
Average weight green tops per crown, pounds
(Nov. 8)
74
2.
Yield of spears, 1925 (Feb. 25-Apr. 1):
Average number spears per crown
1 95
Average weight spears per crown, grams
42 66
Average weight single spear, grams
21 90
3.
Top growth, 1925:
Average number of stalks per crown (Oct. 10)
Average weight green tops per crown, pounds
(Oct. 10)
5.14
2.33* 1.42t
8.61
238 78
4.
Yield of spears, 1926 (Mar. 5-Apr. 25):
Average number spears per crown
Average weight spears per crown, grams
Average weight single spear, grams
27 73
Yield per acre, pounds
1612 14
5.
Top growth, 1926:
Average number stalks per crown (Oct. 2)....
4 69*
Average weight green tops per crown, pounds
(Oct. 2)
2 23 1 56 t
* With berries.
f Without berries.
Thus far the staminate plants are superior to pistillate plants in
that they produce a larger number and a greater weight of spears.
Pistillate plants, however, produce a greater proportion of large
spears than do staminate plants; that is, the average weight of a
single spear is greater. The food-making surface of the staminate
plants, as expressed in the weight of the mature green tops con-
sistently exceeds that of the pistillate plants. If the berries, which
constitute approximately 30 per cent of the green weight of the plant,
are excluded, the tops of staminate plants weigh only slightly less
than double those of pistillate plants. In the case of both pistillate
and staminate plants there is a close relationship between the weight
of the top growth and the yield of spears the following season.
The question arises whether or not the differences between stami-
nate and pistillate plants will last throughout the productive life of
the plantation. The tendency thus far expressed may be shown by
comparing 1925 and 1926 spear production records.
34 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
A comparison of the performance of staminate and pistillate plants
during two consecutive years (1925 and 1926) shows that the differ-
ences between staminate and pistillate plants, as expressed in 1925,
are still greater in 1926. The harvest in 1927 showed approximately
the same differences between males and females as in the preceding
year.
Crown Selection on a Sex Basis. — The results cited in the fore-
going paragraphs immediately raise the question as to the practica-
bility of segregating the crowns at the time of digging on the basis
of their sex and of planting staminate crowns only. Under climatic
conditions of the asparagus growing sections of Europe, and of the
eastern United States, the plants do not come into bloom until the
second year from seed. It has been thoroughly established that one-
year plants are much superior to older ones; for this reason, growers
would be reluctant to allow the plants to stand in the nursery until
the second year in order to afford them an opportunity to select male
crowns. B6ttner (4) (Germany), writing in 1921, describes what he
calls the "Bottner System." It is based upon the recognition of the
superiority of male over female plants. In order to overcome the
difficulty of weakened two-year-old crowns, he transplants one-year
crowns to a new bed, setting the plants about 4 inches apart in rows
about 12 inches apart. The roots are not crowded and the plants
remain vigorous. This method entails much extra labor, and according
to Bottner, staminate crowns so selected cost double that of unsorted
crowns. He further states, however, that the increased yields obtained
over a series of years more than pay for the difference in the original
cost of crowns.
As pointed out above, under California conditions a large per-
centage of asparagus plants bloom the first year from seed. It is
possible to go through the nurseries in the summer and fall and pick
out staminate plants. One who is trained can readily distinguish male
and female plants by the flower characters. It is highly probable that
the operation of segregating the crowns on the basis of their sex will
prove to be entirely practicable. Experiments are now under way to
determine this.
It has been ascertained thus far that the percentage of plants
expressing their sex the first year is influenced by the spacing in the
nursery. For example, in 1926 at the University Farm, in plots
where rows were 2 feet apart, the percentage of plants that had
bloomed by September 3 was 30 to 40 per cent higher than in plots
the rows of which were 1 foot apart. Undoubtedly other factors, such
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 35
as time of planting, available salts in the soil and available water also
influences the time of flowering. Experiments are now under way
to ascertain the influence of these factors.
COMPOSITION OF THE ASPARAGUS PLANT AND FERTILIZERS
Chemical analyses of the different organs of the plant are of some
interest in relation to the nutrient requirements. Analyses made at
frequent intervals throughout the life of the plant show the time and
rate of absorption of the various elements, and the time of translocation
of storage products both to and from the storage organs. Analyses of
the edible part of the plant also show to a certain extent its relative
food value.
Composition of the Boots and Root stocks. — Analyses of the roots
and rootstocks of asparagus have been made by several investigators
and at different seasons of the year. In general, it may be said that
there is a pronounced exhaustion of sugars in these organs, resulting
from the production of spears, but that the percentage of the other
constituents remains almost constant.
Composition of the Edible Shoots. — There is variation in the results
reported by different workers as to the composition of the edible
shoot. Nothing is indicated as to variety, age of bed, cultural prac-
tices, soil, climate, and date when samples were taken, all of which
would undoubtedly influence to some extent their composition.
Under Massachusetts conditions data (Morse (16) ) show that during
the progress of the cutting season there is an increase in the sugar
content of the shoots and a decrease in the protein and lignin. It is
suggested that the change in the amount of sugar is due to photo-
synthesis carried on by the shoot itself and not to any greater move-
ment of sugar from the roots and rootstock.
Asparagus has a high water content, about 92 or 93 per cent. The
fat content of the edible shoots is about 0.25 per cent, the nitrogenous
constituents slightly less than 2 per cent.
Composition of Asparagus Tops. — Rousseaux and Brioux (19)
report that, in France, the dry matter in the tops removed in late
autumn from the fields amounts to about 1,400 pounds per acre.
Morse (16) estimated that the asparagus tops contributed approximately
1,500 pounds of organic matter to the acre each year. During the
ripening of the tops there is a decrease in the amount of sugar and
protein. These constituents are undoubtedly translocated to the roots
and rootstock.
36
UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION
Mineral Nutrients Removed from the Soil by the Asparagus
Crop. — A number of workers have computed, upon the basis of the
composition of the plant, the mineral nutrients removed per acre by
the asparagus crop (fig. 20). As would be expected, there is much
variation in these results.
8
is
I
66
"§ 22
I
f\l m-mm—m—m
/y
i< P n
/
A U
/
/
pa s
~
A j
MyU
/ /
/ /
/ x
/ /
/ /
/ /
// /
// /
/ /
y
/
s
s ^
/
jr . ' s
_-, 1 i
$
End of April June 24
End of cutting
November
Cutting of tops
Fig. 20. — Pounds of fertilizer elements absorbed by asparagus plant during
the growing season. Data from Kousseaux and Brioux.
Rousseaux and Brioux (36) studied five different plantations in
France ; their analyses show the materials carried away by the entire
crop of asparagus, including the spears, tops, and berries. No
mention is made of the age of the beds from which the samples
were collected. In the spears, nitrogen and potash constitute the
largest proportion of the mineral elements. These elements usually
occur in large amounts in growing tips and where cells are- under-
going rapid division. Considering the material removed by the entire
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 37
top growth, including both spears and mature stalks, the principal
fertilizer constituents removed are nitrogen and potash. It is worthy
of note that of the total amount of these constituents used for the
entire top growth, a relatively small percentage, with the exception
of phosphoric acid, is found in the edible spears. The high percentage
of the total phosphoric acid which occurs in the edible shoots is note-
worthy. The results of Warren and Voorhees (25) in the United States
are comparable with those obtained by Rousseaux and Brioux in
Prance.
The edible portion is relatively rich in phosphoric acid, but the
tops used much more nitrogen, potash, and phosphoric acid than did
the edible spears that were harvested.
If the tops are burned on the bed, the phosphoric acid and potash
are not removed, so that the amount lost is not large.
Fertilizing Asparagus. — There is a great amount of conflicting
data bearing upon the fertilizing of asparagus. Many of the fertilizer
tests and experiments have borne results which one must regard as
inconclusive. It is almost impossible in our present state of knowledge,
to make definite recommendations. A practice which has brought
rewards in one locality may be unsuited to another locality. In many
instances, however, the reasons for this difference of response are not
well understood. It is very probable that the practices of France and
the eastern United States can be no more than suggestive to the growers
in California, where conditions are so different. On the rich soils of
the Delta, very little increased production has been obtained from the
fertilizers that have been tried. The Delta growers, however, are not
indifferent to the fertilizer problem. They are interested in develop-
ing fertilizer practices which will lengthen the profitable life of the
asparagus bed, and will also give an increased yield. In some sections,
especially the East, the fertilizer problem is probably the most acute
one with which the grower is confronted.
Some Results of Fertilizer Experiments, and Fertilizer Practices. —
The experiments of Brooks and Morse (5) in Massachusetts seem to
show that on sandy soils moderate applications of chemical fertilizers
are followed by as good yields of asparagus as when manure in com-
bination with chemical fertilizers or manure alone is used.
In Maryland (8) a fertilizer experiment was started in 1905 on a
bed planted in 1903. The soil is reported as being "medium loam of
good fertility." Results similar to those of Brooks and Morse (5 ' were
obtained, with the exception that heavy applications (20 tons per
acre) of manure alone gave highest yields, but not the largest net
profit.
38 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Warren (25) gives the results of fertilizer experiments in New Jersey
from 1897 to 1906. There were four plots, each one-eighteenth of an
acre in size, which were given the following treatments: Plot 1
received an application of barnyard manure at the rate of 20 tons
per acre each fall. Plot 2 received an application of complete fer-
tilizer every spring at the rate of 500 pounds per acre. This analyzed
4.5 per cent nitrogen, 7.7 per cent phosphoric acid (available), and
13.3 per cent potash. Plot 3 received the same treatment as plot 2,
with the addition of 150 pounds each of ground bone and muriate of
potash each fall. Plot 4 received the same treatment as plot 3, with
the addition of 200 pounds of nitrate of soda, each year after the
cutting season. In 1905 and 1906 the application of the complete
fertilizer on plots 2, 3, and 4 was doubled, but all other treatments
remained the same. The results are similar to those obtained in
Massachusetts, from which the conclusion is derived that in a number
of cases 200 pounds of nitrate of soda per acre gave as good or even
slightly better yields than larger amounts. The plot receiving annual
applications of 20 tons of manure per acre gave the largest yields.
The experience of most French and German growers is that
manure cannot be replaced entirely by commercial fertilizers. Their
practices are based upon experiences over long periods of time. For
example, in the Yonne District, France, the growers usually apply
each year from 12,320 to 13,200 pounds of manure per acre, this being
equivalent to about 72 pounds of nitrogen, 29 pounds of phosphoric
acid, 88 pounds of potash, and 139 pounds of lime. Not all of this
manure becomes available to the plant the first year. It is estimated
that approximately 20 per cent of the nitrogen becomes available the
first year, the remainder becoming available gradually during the
succeeding years.
In the Loir-et-Cher (France), in addition to a fall application of
approximately 12 tons of stable manure to the acre, 640 pounds of
slag, 180 pounds of potassium chloride, and 254 pounds of gypsum
are also applied. Instead of potassium chloride, 530 to 570 pounds of
common sylvinite may be used. The commercial fertilizers are spread
in the fall or in February and turned under.
Experiments in the Cote d'Or, of France, indicate that manures
alone are comparatively too expensive and do not produce the largest
crops. They seem to show that it is advantageous to supply half of
the needed material in the form of manure and one half as commercial
fertilizers. Experiments there show that the best results are obtained
when 13,200 pounds of manure, 88 pounds of potassium sulfate, 264
Bul. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 39
pounds of slag, and 88 pounds of potassium nitrate are applied per
acre. These fertilizers are turned under in the fall. In addition to
these 88 to 132 pounds of nitrate of soda to the acre are spread in
April at the time of hilling. It is further stated that asparagus grown
on land fertilized with both manure and commercial fertilizers is of
larger size than that grown on land fertilized with manure alone.
Rousseaux and Brioux (19) estimate that the edible sprouts har-
vested during a 60-day period use 30 per cent of the nitrogen, 50 per
cent of the phosphoric acid, 22.5 per cent of the potash, and 4.7 per
cent of the lime of the total amount absorbed by the crop during the
year. These workers maintain that the plants must have an abundance
of phosphoric acid available at the beginning of the growing season.
For phosphoric acid, they recommend the use of slag in sandy soils
and super-phosphate in silicious-calcareous soils, and state that the
potash should be applied in the form of a sulfate rather than a
chloride. In this connection, it should be noted that experiments in
the United States show that potassium in the form of chloride gives
better results than when the potassium is applied in any other form,
such as the sulfate or w T ood ashes.
Meyer (15) (Germany), basing his conclusions upon experiments,
states that asparagus should receive applications both of stable
manure and artificial fertilizers. He recommends stable manure the
first year and artificial fertilizer the second, continuing this alter-
nation throughout the life of the bed. The manure is applied at the
rate of about 5 tons to the acre, in rather deep furrows. The com-
mercial fertilizer which he claims has given the best yields and shoots
of the most superior quality, is a mixture of equal parts of 40 per
cent potassium slag, superphosphate, and sodium nitrate. This mix-
ture is applied broadcast at the rate of about 300 pounds to the acre ;
it is then cultivated into the surface soil.
Time of Application of Fertilizers. — The time to apply fertilizers
to asparagus has been much debated.
Close (7) concluded from his experiments (Delaware) that appli-
cations of sodium nitrate to asparagus beds during the cutting season
in order to increase yields during the season of application could not
be recommended.
Experiments with sodium nitrate fertilizers conducted in Massa-
chusetts by Brooks and Morse (5) bear out the above conclusion. They
found that summer applications or divided spring and summer appli-
cations of manure and sodium nitrate gave better results than the
spring application.
40 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Meyer (15) (Germany) is emphatic in the statement that the best
time to apply fertilizers to asparagus is immediately following the
harvest season.
French experience seems to be not altogether in harmony with that
expressed above. Rousseaux and Brioux (19) (France) recommend
that phosphates and manure be spread in the winter and plowed
under together; that potash fertilizers and a part of the nitrate
should be applied in March; that the nitrate should be applied at
three different times : one-third in March, one-third at beginning of
the cutting season, and one-third late in May. In the district of
Vauclese, the commercial fertilizers are applied at hilling time.
It is recommended from experiments conducted in the Cote d'Or,
France, that all the fertilers, except the nitrate, be plowed under in
late fall, and that the nitrate be spread in early spring at the time of
hilling.
B6ttner (4) (Germany) recommends manuring just at the close of
the cutting season at the time the mounds are leveled, regardless of the
type of manure that is used. Best results are obtained by the use of
compost spread between the rows and covered with dirt obtained from
the ridges. He claims that manure applied immediately after the
cutting season will stimulate growth and benefit the following harvest,
while if applied in late fall or winter the following harvest will not
be benefitted.
Influence of Fertilizers on the Quality of the Shoots. — In the Cote
d'Or district of France, a "tasting commission" made a special study
of the taste of asparagus as influenced by different fertilizers and other
conditions. They report : (1) when asparagus is grown in a naturally
moist, non-calcareous sandy soil, where manure alone is used as a
fertilizer, the shoots lack taste and are slightly bitter : any application
of sodium chloride develops a sweeter taste; (2) iron sulfate and
gypsum improve markedly the taste of the shoots; (3) nitrogen gives
a better flavor to the spears when added in the inorganic form as
nitrate of soda than when added in the organic form; (4) dried blood
gives the shoots a marked bitter taste; (5) potash in the form of
sulfate makes more pronounced the peculiar taste of the asparagus
spear, while kainit tends to reduce it; (6) phosphoric acid tends to
develop the desired asparagus taste, while a lack of it produces a less
desirable taste.
There are probably other factors besides fertilizers which influence
the quality of asparagus. In almost any field, there are some spears
which are decidedly more bitter than the average. It has been
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 41
suggested that slow growth may be responsible for this bitter flavor.
Some growers state that there is a marked difference in the flavor of
asparagus harvested at different times of the year. Some canners
consider that the best quality of canning asparagus is grown during
the month of May. There is need for further careful study and
analysis of the factors which influence the quality of asparagus.
Asparagus and Salt. — Walker (24) conducted a number of experi-
ments in Arkansas on the use of salt as a fertilizer for asparagus. His
results, based upon a. single season's work, show a difference of 13.5
per cent in favor of the salted areas. He states, also, that the differ-
ence was not confined to the spring growth but that increased vigor
was evident throughout the summer. The salt was broadcasted at
the rate of 1,000 pounds to the acre. The asparagus was not cut
during the season of application, but no appreciable effect upon the
growth of the plants that season could be seen, nor was there any
prevention of the growth of weeds. The following year a much heavier
application was given the same part that had received salt the pre-
ceding season. Two pounds per square yard was applied in two equal
applications at intervals of two days.
Walker is of the opinion that salt is beneficial for the following
reasons: (1) it tends to bind or compact lighter soils; (2) it tends to
improve capillarity; (3) owing to its power of absorbing water, it
tends to increase the moisture in the soil; and (4) it keeps down weeds.
The more recent experiments of the Rhode Island Experiment
Station seem to show that sodium "has little or no direct manurial
action, but may influence the growth of certain plants by the effect
of the chemical reaction of the soil. ' '
Rudolf s (20) experimented with top-dressings of sodium chloride, in
addition to manure. He made applications upon two-year-old and
eleven-year-old asparagus plants. Applications of common rock salt
(Retsof agricultural salt) were made at the rate of 150, 300, and 500
pounds per acre. Cuttings of spears were made the same season that
salt was applied. After the cutting season the stems of the plants
were counted and the length measured at intervals of from seven to
ten days. The following spring the same amounts of salt were again
applied, and the spears were weighed, counted, and graded for market
purposes. There was an increase in the number and weight of spears,
but these were of a poorer grade. The number of stalks and the total
length of the plants increased regularly in all series, the stalks reach-
ing their maximum height in the middle of the growing season. At
the last measurement taken, the average total lengths per plant of the
42 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
two-year-old asparagus plants on the plots receiving 150, 300, and
500 pounds of salt per acre were, respectively, 21.1, 28.6, and 38.7
per cent higher than the average lengths of plants on the check lots.
The counting of the stalks was continued until September 6 and
the increase in the average number for the plots receiving 150, 300,
and 500 pounds of salt per acre was found to be 2.9, 16.2, and 26.8
per cent, as compared with the check plots.
Asparagus grown on this soil seemed to be stimulated directly by
the salt applications, for weeds were kept down by hand on all plots
throughout the growing season.
With solution cultures, Working (27) found that young asparagus
seedlings gave a better yield in all plots where sodium was added
except at the concentration of 0.5 molar, and with another solution
where it was thought that the large amount of magnesium caused the
lesser growth. The chlorine did not show the specific action that
might have been expected from fertilizer work reported by other
writers. Working thinks that "it is perhaps the magnesium which
causes the shortening of the life of the asparagus beds in the lower
islands of the Sacramento River, where brackish water is carried up
by the tide."
GROWING AND HANDLING ASPARAGUS CROWNS
Growing Versus Buying Crowns. — Commercial asparagus growers
generally grow their own one-year-old crowns. There are several
reasons for doing this: (1) It usually costs less to grow crowns than
to buy them. This applies especially to large acreages such as are
usual when asparagus is grown for canning or as a truck crop.
(2) The grower has information regarding the seed. When he pro-
duces his own seed, he is familiar with the variety and performance
of the beds from which the seed has been obtained. Seed for planting
the nursery may be obtained from reliable sources, either firms or
individuals, who know the principles of selection and give special
attention to the improvement of this crop. Since the yields from
asparagus extend over a period of ten or twelve years, extra effort
can well be expended in securing the best seed. Using cheap seed is
not economy. (3) There is opportunity for rigorous crown selection.
Even under conditions conducive to the best crown development some
grading should be made. Consequently, it is necessary to grow a
surplus so that there will be a sufficient number of good crows for
planting. Some nurserymen and seedmen sell only the best crowns,
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 43
but as a general rule very little grading is done. (4) Delayed plant-
ing can be avoided. The best results are obtained, as regards
immediate growth and perfect stand, when the crowns are set shortly
after digging. (5) In California, climatic conditions are conducive
to good crown development. On account of the long growing season
and the large amount of sunshine prevalent during the spring,
summer and early fall, plants make a greater growth in one season
in California than in most parts of the country. For these reasons
it is deemed highly desirable that growers raise their own crowns.
If only a few crowns are to be planted as in the case of the home
garden, it is usually cheaper to buy them from a reliable nurseryman.
The buyer should specify that only well developed one-year-old
crowns will be accepted.
Types of Soil. — Good asparagus crowns can be grown on soils of
various types. The best soils, however, for the production of nursery
stock are well-decomposed peat, or light, sandy loam. These soils are
open and porous and facilitate root penetration and elongation. One
of the most important reasons, however, for choosing light soils for
the nursery is that crowns may be dug with a minimum of injury.
Excellent crowns can be produced on light sandy soils if fertilizers
and a sufficient amount of water are applied.
Heavy soils can be used for the growing of crowns ; to keep them
in good physical condition, however, requires a great amount of labor.
They usually remain wet till late spring, especially in regions of
heavy winter rainfall, and they warm up more slowly than in the
lighter soils, thus delaying germination and retarding the growth of
the plant after germination. Also, since heavy soils become packed,
it is difficult to dig the crowns without injuring many of the root-
stocks and losing a large percentage of the fleshy roots. As these roots
contain the reserve food supply, their loss is bound to weaken the early
growth of the plant.
Preparation of the Seed Bed. — Land that is sub-irrigated should
be nearly level so that uniform moisture conditions can be main-
tained. On surface irrigated land a slight fall is necessary. The
soil should be comparatively free from clods. A fine, well pulverized
seed bed permits the soil particles to come into close contact with the
seed, insuring a constant water supply and rapid germination.
Seed Treatment. — Under average field conditions it is usually from
two to six weeks before the plants appear above the ground, this
variation depending upon the temperature and moisture of the soil
and the depth of planting.
44 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Methods have been used to overcome difficulties resulting from
slow seed germination. These are: (1) The sowing of quick germi-
nating seeds, such as radishes, with the asparagus seed. The radish
plants soon appear above the ground and mark the rows so that the
grower is better able to cultivate between them. (2) Soaking the
asparagus seed in water.
The first method is little used and growers differ as to the utility
of the second.
Borthwick (3 ' obtained good results only when the soaked seed was
planted in moist soil. Contact with dry soil even for a day destroyed
the effect. The temperature and time of soaking seed may vary con-
siderably and still give beneficial results. A temperature of 86° F
for four or five days is recommended. Soaking in water at the
ordinary temperatures of the air (70° to 75° F) for short periods of
time has little effect.
After the seed is removed from the water, it should be spread out
thin on a canvas, stirred for a few minutes until the water disappears
from the surface, and then planted immediately. The soaked seed
will be hard and firm, and after drying for a few minutes, may be
planted with a drill or by hand. If the seed is dropped by hand
in the furrows, moist dirt should be drawn over it and firmed
immediately.
Planting Season. — Early planting of seed is advised in order that
the plant may have a long growing season during which to develop
a large crown. The date of planting, however, must be governed
largely by local and seasonal conditions. On the peat lands of the
Delta region of California, seed can be sown in late February or
March. In the Imperial Valley seeding can take place somewhat
earlier.
Methods of Planting. — The seeding is usually done with garden
drills, and occasionally by hand. When large acreages are planted,
the drills are arranged in gangs, and two or more rows are sown
simultaneously. A number of growers in recent years have adopted
the method of sowing the seed in furrows 3 to 6 inches wide in order
to give the growing plants plenty of room to develop and still produce
a large number of crowns to the acre. This method is better than
planting too thick in narrow rows, but it is unsatisfactory on foul
land, as a great deal of hand work is necessary to keep the rows free
from weeds.
Where surface irrigation is practiced, the seed is usually sown on
ridges or beds, similar to those used in the growing of lettuce. If the
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 45
spring rainfall is plentiful, the seed can be sown on the level, as the
plants will be large enough for furrowing between the rows by the
time irrigation is necessary. It is best to sow on the level or on low T
beds in those regions where strong drying winds are prevalent.
Rate of Seeding. — The tendency among growers has been to sow
the seed too thick. Not more than five pounds should be planted to
the acre. Best results are obtained when the rows are about 24 to
30 inches apart and the plants 3 to 4 inches apart in the row. If the
seeds are dropped in groups of two or more, fleshy roots and root-
stocks become so interwoven that it is difficult to separate them at
Fig. 21. — Asparagus nursery.
sorting time. The most expensive single operation in connection with
the present method of producing crowns is that of separating the
different individuals after digging. This expense can be greatly
reduced by thinner seeding. Moreover, injury is often done to the
crowns in separating them w r hen they are grown in thickly matted rows.
Depth of Planting. — The proper depth of planting varies with the
type of soil. In peat soils the seeds can be planted 2% to 3 inches
deep. There is little advantage in deep planting except to keep the
seed in contact with a permanent moisture supply and thereby insure
quick germination. In sandy loam and light sandy soils, the seed
should be planted from 1% to 2 inches deep.
Intercropping. — Companion planting and intercropping are often
practiced in the production of nursery stock. Good crowns can be
46 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
grown in young orchards where plenty of sunlight is available, but
the young asparagus plants will not do well in the older orchards
where there is too much shade. Some growers raise nursery stock
between the asparagus rows that have just been set in the permanent
field. This is undoubtedly an undesirable practice, especially from
the standpoint of the permanent bed. The seedlings rob the soil of
plant food that is needed for the growth of the transplanted crowns.
Moreover, the volunteer crowns which remain after digging are rather
hard to eradicate for a year or two.
Thinning. — It is doubtful whether thinning is practical. Seeding
should be regulated so as to get the desired stand without thinning.
The method of plant development makes the thinning process very
difficult. This operation must be performed before the second aerial
shoot appears and before the development of the fleshy root system
begins. The shoot usually breaks off at the crown when an attempt
is made to pull the plant. If the crown remains in the soil, shoots
again appear in a few days. After the fleshy roots have once started
to develop, the only way to thin is to dig out the crown ; in doing this,
however, there is danger of injuring adjacent plants.
Irrigation. — The soil about the developing rootstock and fleshy
roots must be kept moist if the best growth is to be obtained. The
fleshy roots will not elongate in dry soil. Fleshy roots that have
started to grow in moist soil stop increasing in length when the soil
becomes dry. Crowns which have a large number of short, fleshy
roots have usually been subjected to periods of drought. Water
should not be added, however, after* the early part of September. If
the soil is kept moist, new shoots continue to appear as long as the
temperatures are sufficiently high for growth to take place. Shoots
appearing late in the fall make a considerable demand upon the stored
food in the crown.
Cultivation. — The manner of cultivation should vary with the type
of soil and the method of planting. In weedy fields, cultivation is
often necessary before the seedlings appear above the ground. If
radish seed has been drilled in with the asparagus seed the rows can
be seen within three or four days. Cultivation may be started as soon
as the rows are visible. Hand cultivation with a wheel hoe is usually
practiced where the rows are close together. In the case of surface
irrigation it is necessary to cultivate the ground just as soon after
each irrigation as the soil can be worked. In case of horse cultivation,
care must be taken not to injure the fleshy roots and rootstocks by
plowing too deeply or too near the row, especially late in the season
BlJL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 47
after the roots have spread through the soil surface. The roots spread
from the rootstock in the shape of a cone. They are nearest the
surface where they are attached to the rootstock.
Digging the Crowns. — Crowns are usually plowed out during the
late fall or early winter. The tops should first be cut with a mowing
machine and then raked and burned so that they will not interfere
with the digging operation. The crowns can be turned out with a
two-horse moldboard plow. Another implement that has proved very
satisfactory for loosening crowns in the nursery is a U-shaped knife
that runs under the mass of fleshy roots and straddles the row. The
knife at the bottom should be at least 8 inches wide with an upward
tilt toward the rear, so that it will loosen the soil about the crowns
and make it easier to lift them. The latter method of digging is
especially adapted to rows that are planted far apart, in which case
a large part of the root system can be saved. Whenever possible, the
fleshy roots should be obtained uninjured. If the growing point of
the fleshy root is not injured, it will continue to elongate after
planting (fig. 8).
A short-handled six-tined manure fork may be used to lift the
crowns out of the soil and shake out the loose dirt. The crowns are
then thrown in windrows or small piles and allowed to dry for an
hour or so before they are hauled from the field.
Crown Storage. — When hauled from the field, the crowns should
be placed on a dry floor or on well-drained ground. The best storage
temperature is about 40° F, but they can be stored for a long period
at much higher temperatures if the atmosphere is dry. If the crowns
become moist from heating or from rain or heavy fogs, they soon
decay. Hundreds of thousands of crowns are lost each year because
of rotting. The fleshy roots contain large amounts of sugar, which
is an excellent medium for the growth of mold organisms. Mold
spreads very rapidly in the presence of moisture and a high tempera-
ture, such as often exists when crowns are stored in large piles. There
should be ample opportunity for air to circulate between the crowns.
If crowns must be stored in large piles, it is well to refork them at
intervals of three to four days to loosen the pile, thus facilitating
aeration and thereby preventing heating and ' ' sweating. ' ' The plant-
ing of crowns that have been stored in large piles and injured by
molding is one of the most common causes of poor stands in the field.
The buds may be dead, even though the fleshy roots appear sound and
healthy. In more severe cases, both the fleshy roots and the buds
may be dead.
48 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION
The crowns should not be stored where they are subject to desic-
cating winds for a long period. Though crowns will stand a great
deal of drying, growth response is much more rapid if they are
not subjected to extreme desiccation. The best results are obtained
when the interval between digging and planting is short.
Shipping Crowns. — Crowns are often transported in bulk for great
distances by auto truck and rail. If not otherwise protected, they
should be covered with canvas to prevent them from getting wet or
from drying out. For distance shipments, asparagus crowns should
be packed in crates or in loosely woven burlap sacks. Care should be
exercised that the crowns are not packed so tightly, or to such a depth,
that free circulation of air about them is prevented. Failure to pro-
vide good aeration will result in "heating" and molding, and extreme
injury to the buds and roots.
Age of Crowns to Plant. — It is the experience of asparagus growers
than one-year-old crowns are superior to older ones. B6ttner (4) (Ger-
many) calls attention to tests in which one, two, and three-year-old
crowns were planted in adjacent rows and the yields determined at
the end of four years. The yield from one-year-old crowns was almost
double that from two-year-old crowns, and treble that from three-
year-old crowns. If the crowns are permitted to remain two years
in the nursery under crowded conditions, growth is checked and the
plants seem to be very much weakened. Moreover, on account of the
intertwining of the roots, two-year-old crowns cannot be easily separ-
ated without injuring many of the roots. One-year-old crowns may
be dug with less injury to the roots and less interruption to their
growth.
Crown Selection. — Large acreages of asparagus have been planted
in years past without selection of crowns. The experience of European
asparagus growers seems to have been that it pays to practice crown
selection. With them, it is a matter of course. Many asparagus
growers in this country, however, still believe that rigorous selection
is impracticable.
At the present time some experimental data in support of crown
selection are available. In the 1916 Annual Report of the Pennsyl-
vania State Agricultural College, Myers (17) reports the results of
crown selection of two varieties, Palmetto and Argenteuil. One-year-
old crowns were divided into three grades: No. 1 (the largest), No. 2
(medium), and No. 3 (the smallest). The weights of the different
grades are not given. The crowns were planted in the spring of 1908,
and asparagus was cut for the first time in 1910.
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
49
Fig. 22. — Grades of crowns: " Number 1," "Number 2," and "Number 3."
It should be the aim of the grower to produce ' ' Number 1 ' ' crowns to plant in
the permanent field. (From Bul. 381.)
50 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
There was no striking difference between the yields obtained from
the No, 1 and No. 2 crowns. In no case, however, did the No. 3's
produce as much as the other two grades, even after a period of six
years.
Experiments to determine the relative value of crowns of different
sizes were started in New Jersey in 1924. The Atlock strain of
Palmetto was used. Three grades of roots were selected, "firsts,"
"seconds," and "culls." The plants were raised in 1923, and the
crowns transplanted in 1924.
In a brief account of this experiment, the statement is made that
"Since it is well known that the yield of asparagus in any year
depends upon the growth made the previous season, if this growth is
measured, we can get a general idea of what our asparagus will do."
The conclusion is drawn that "The results indicate that culls do not
make a good enough growth to warrant planting, but the difference
between first and seconds was not enough to be worth considering."
Those crowns should be selected for planting purposes that are
large in size, have large buds, are fresh, uninjured, and free from
disease.
Crown Desiccation. — Some tests were started at the University
Farm, Davis, California, in 1924 to determine to what extent growth
was retarded and yields reduced when the crowns were dried for a
period.
Crowns were stored in burlap sacks in a dry room subject to the
same temperature fluctuations as the outside atmosphere. There were
118 crowns in each sack, a number sufficient to plant one row in
the experimental plot. The crowns were set in the permanent bed
March 29, 1924, after being exposed to atmospheric conditions for a
period of 53 days. The crowns lost approximately 20 per cent of
their weight during the time they were kept in storage. They were
planted in furrows 8 inches deep and covered with about 2 inches
of soil. Water was then run in the furrows over the crowns. At
intervals, a count was made of the crowns having aerial shoots. Even
under the most ideal growing conditions it was 34 days before any
shoots appeared above ground. Fifty-two days after planting 75 per
cent of the plants had shoots above ground. Eventually a perfect
stand was obtained.
The influence of root desiccation upon the yields of asparagus
spears during the first two cutting seasons is shown in table 4.
Allowing the crowns to dry out before planting caused a reduction
in yield of 324 pounds per acre the first year and 426 pounds the
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
51
second year below that of crowns planted in the permanent field
shortly after removing from the nursery.
Crown Selection and Replanting. — Crown selection is justified
even if for no other reason than to reduce the amount of replanting.
On a California ranch, 1,814 acres of asparagus were planted in the
spring of 1921 ; 3,418 ungraded crowns were set on each acre. Care
was taken to plant the crowns properly and they were given the
required attention subsequently. The per cent stand in August,
1922, was 64. This necessitated considerable expense in replanting.
The labor cost alone of replanting in this case amounted to $1.25 per
1,000 crowns, and the crowns needed for replanting cost $4.00 per
TABLE 4
Influence of Root Desiccation upon Yield of Speaks
Treatment
Total
number of
crowns
Average
number of
spears
per crown
Average
weight of
spears
per crown
Average
weight of
single
spear
Yield
per acre
(pounds)
1925:
Roots desiccated
352
353
352
353
1.86
5.27
11.13
14.89
39.41
90.11
294.23
360.31
21.14
17.08
26.45
24.20
250.25
Roots not desiccated
1926:
Roots desiccated
573.83
1,868.38
Roots not desiccated
2,294.47
1,000. To the above costs of replanting must be added the losses due
to decreased yields. In the case cited, 38 per cent of the plants were
at least a year behind the others. It should be added that subsequent
plantings on this same ranch, on a similar type of soil, using, however,
only selected crowns, resulted in almost 100 per cent stands.
Division of Crowns. — Asparagus can be propagated by division of
the crown. This method of propagation, however, is not employed
commercially. It was formerly used to only a limited extent in plant-
ing the home garden, but the prevailing practice now is to use one-
year-old crowns. Propagation of asparagus by division of the crowns
has been employed in breeding operations. If one wishes to multiply
a desirable male or female plant for breeding purposes, this can be
done by division of the crown. These can then be planted in an
isolated bed.
Root Pruning. — Root pruning is not generally practiced in plant-
ing large acreages of asparagus. In some cases, however, growers
prune back the fleshy roots to within 3 or 4 inches of the buds. This
is done mainly to facilitate handling and planting.
52
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
The influence of root pruning on the yield of spears during the
first two cutting seasons is shown in table 5. All plots were planted
in triplicate. All but 4 inches of the roots were pruned off, causing
a loss in weight of about 25 per cent.
TABLE 5
Effect of Root Pruning on Yield of Spears
Treatment
Number
of crowns
Average
number of
spears
per crown
Average
weight of
spears
per crown
Average
weight of
single
spear
Yield
per acre
(pounds)
1925:
Roots pruned
352
353
352
353
2.46
5.27
14.15
14.89
47.52
90.11
327.88
360.31
19.31
17.08
23.17
24.20
301.77
Roots not pruned
573.83
1926:
Roots pruned
2,082.05
2,294.47
Roots not pruned
Pruning of the roots caused a reduction in yield of 272 pounds
per acre the first year and 212 pounds the second year. Plants that
had their roots pruned at time of transplanting are no doubt given
a more severe check at time of transplanting than those unpruned.
A portion of the food reserve is removed, pruned roots do not continue
to elongate and the surface for the development of fibrous roots is
also reduced.
ESTABLISHING THE PLANTATION
Soil Type. — Soil type is a very important consideration in the
profitable production of asparagus. At present this crop is grown
on many different soil types, from clay to sandy loam and muck.
Where early growth is necessary for profitable production, as in the
Imperial Valley of California, Georgia, South Carolina, New Jersey,
and to a certain extent, in the Delta region of California, a soil that
warms rapidly in early spring has a decided advantage.
On the eastern seaboard of the United States, in the Middle West,
and in the Imperial Valley and San Fernando Valley of California,
most of the large plantings are on soils varying from silt to light sand
and sandy loam. On sandy soils tillage is less difficult and less expen-
sive ; such soils are well aerated, dry quickly after a rain or irrigation,
do not form a hard crust over the row, and produce a more uniform
and attractive product than can be obtained on the heavier soil types.
Very light sandy soils, however, are not as desirable, especially if the
subsoil is a light sand or gravel. The subsoil should be retentive of
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 53
moisture, and open and porous enough to facilitate drainage and to
allow root penetration and aeration.
Clay soils are not desirable for commercial asparagus production,
mainly because they warm up too slowly in the spring. Clay soils are
also difficult to manage. While the yield may be as high or higher
as on the lighter soils, if grown for market the bulk of the crop is
produced late in the season when the prices are low. The percentage
of crooked spears is higher on the heavy than on the light soils.
In the Delta region of California, practically all of the asparagus
is planted on muck or a mixture of muck and river sediment. Muck
makes an ideal asparagus soil ; it warms up rapidly in the spring of
the year; it is loose and friable and the spears can make a straight
upward growth. Muck has a high water-holding capacity and is
comparatively easy to work.
Because of the high sodium chloride tolerance of asparagus it is
possible to use land for this crop that has a salt content too high for
the production of many other crops. In the Suisun Bay region of
California, there is a large tract of land subject to salt water irri-
gation during the latter part of each summer and fall. Much salt is
washed out each winter during the rainy season, but by evaporation
from the surface, the salt content increases in the upper layers
throughout the summer. The salinity of these soils is especially high
after a winter of low rainfall, as the salt is not washed out of the
soils, and, too, there is not sufficient fresh water produced by the
melting snows of the high Sierras to keep the highy concentrated
saline waters flushed out of the lower river channels. Asparagus
planted on these saline soils has done exceptionally well. It is the
practice in the Delta to stop using the river water for irrigation
purposes when the sodium chloride content reaches 1 part in 1,000.
The margin of safety here is very large, for asparagus will withstand
a higher concentration than this.
Previous Crop. — There is little known concerning the influence of
the previous crop upon the growth of asparagus. Previous crops
should be such as to leave the soil loose, friable, capable of being easily
worked and free from weeds.
The Lay of the Land. — Where surface irrigation is necessary,
there should be about 2 or 3 inches of fall to every 100 feet of row.
Where subirrigation is practiced, the beds should be as nearly level
as possible so that the plants will receive water uniformly throughout
the field. If the land is uneven, the high spots will not receive
sufficient water and the low areas will be difficult to drain.
54 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Direction of Rows. — If possible the rows of asparagus should run
parallel with the prevailing winds. This gives good aeration, dries
the plants early in the morning, in case dews are prevalent, and also
prevents the stalks from being broken down across the middles after
the cutting season, thus interfering with cultivation. In the Delta,
it is especially desirable that the rows run parallel with the prevailing
wind as the soil is very light; strong winds blowing at right angles
to the ridge remove dirt from the ridges, continually lowering them
during the cutting season. When surface irrigation is practiced, it
is, of course, necessary to run the rows with the slope of the land in
order to facilitate the flow of water.
Time of Planting. — In most sections of the country, asparagus
crowns are set as early in the spring as the ground can be worked.
In the Delta, planting is usually done at almost any time during the
winter when conditions are favorable. Late fall or early winter
planting is advisable because in years of normal rainfall it is difficult
to do any planting until after the heavy rains have stopped. In the
Imperial Valley of California, the fields can be planted any time
during the winter, as the rains do not interfere.
It is best to set the crowns before the buds have started into
growth and as soon as possible after digging from the nursery.
Distance between Rows. — The distance between rows of asparagus
will depend upon a number of factors : the nature of the product to
be harvested, the fertility of the soil, and the cultural methods to be
employed. In growing white asparagus, it is necessary to hill or ridge
the crowns. In this case, the height of the ridge employed determines
to a certain extent the distance between rows, for there must be
sufficient soil volume between them to form the ridges, In California,
where white asparagus is commonly grown, the usual distance between
rows is ly^ to 8 feet. Green asparagus is usually given a very low
ridge or is not ridged at all; consequently, the rows may be closer
together, the usual distance being 6 to 8 feet. Many of the eastern
growers who produce green asparagus plant the rows as close as 4%
feet. In comparison with wide spacing, a crowded asparagus bed
produces an inferior product, both in size and quality; furthermore,
the productive life of the bed is shorter. French asparagus growers
plant more closely than American growers; but the French growers
fertilize their crop more heavily and rely upon hand labor almost
entirely.
Spacing in the Row. — There is much variation in the spacing of
plants in the rows. The distance between the rows must be taken
into consideration. The root system of an asparagus plant is exten-
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
55
sive, and even with an 8-foot spacing between rows, in a few years
the roots of adjacent rows interlace. In the large plantings of Cali-
fornia, the usual spacing between plants in the row is 18 to 20 inches ;
this is with a distance of 7% to 8 feet between rows. The present
tendency in the asparagus regions of California is to place the plants
farther apart in the row than has been the practice heretofore. Many
growers are now setting crowns 24 inches apart. Closely planted beds
yield the largest crops while the bed is young, but the spears are not
so large after the first two or three years as where the plants are
spaced farther apart. Table 6 has been compiled as a guide to the
number of crowns required to plant an acre.
TABLE 6
Number of Crowns Eequired to Plant an Acre for Different
Spacing Distances
Distance between
Distance between rows, (feet)
plants in the row,
(inches)
4
5
6
7
7.5
8
9
12
10,890
8,712
7,260
6,223
5,808
5,445
4,840
15
8,712
6,969
5,808
4,978
4,620
4,356
3,872
18
7,260
5,808
4,840
4,148
3,872
3,630
3,226
24
5,445
4,356
3,630
3,111
2,904
2,722
2,420
30
4,356
3,485
2,904
2,489
2,310
2,178
1,936
36
3,630
2,904
2,420
2,074
1,936
1,815
1,613
42
3,111
2,489
2,074
1,775
1,659
1,534
1,382
Methods of Trenching. — In the large asparagus plantations of
California, the trenches are usually dug by use of a middle-breaker
with wings or extensions attached to the moldboards, and pulled by
tractor power (fig. 23). One or two trenches are made at a time. The
depth varies from 8 to 12 inches, depending upon the type of soil.
Depth of Planting. — As just stated, the type of soil is a factor in
determining the depth of planting; in a light soil, the crowns can be
set deeper than in a heavy soil. In the light peat soils of the Delta,
the usual depth of planting is 10 to 12 inches. Many years ago it
was customary to plant asparagus crowns very deep, often as much
as 18 inches. This practice is usually unsatisfactory because the
growth starts more slowly in the spring, which makes the crop late.
The data given in table 7, from experiments conducted at Univer-
sity Farm, Davis, give the influence of depth of planting upon spear
production the first two cutting seasons. The soil type is a silt loam.
All plots were planted in triplicate.
56
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Deep planting (12 inches) caused a reduction in yield the first
year of 377 pounds per acre and 727 pounds the second year when
compared with crowns planted more shallow (8 inches). It is entirely
possible that the deeply planted plants would have given a better
account of themselves had the length of the cutting season been
extended.
mmgamm**^
Fig. 23. — One method of furrowing, preparatory to planting croAvns.
The furrows are 8 to 12 inches deep.
TABLE 7
Influence of Depth of Planting on Yield of Spears
Depth of
planting
(inches)
Number
of crowns
Average
number of
spears
per crown
Average
weight of
spears
per crown
Average
weight of
single spear
(grams)
Yield of spears
per acre
(pounds)
1925:
8
353
5.27
90.11
17.08
573.83
12
346
1.36
31.54
23.12
196.88
1926:
8
353
14.89
360.31
24.20
2,294.47
12
346
9.21
251.09
27.25
1,567.26
Placing Crowns. — The crowns may be hauled to the fields loose on
large racks (fig. 24) or in burlap sacks. If the rows are short, the
crowns are placed in piles at the end of the furrows. If the rows are
long, they are placed in piles throughout the field. The droppers
usually carry the crowns in burlap sacks swung from their shoulders
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
57
(fig. 25). The distance between crowns is merely estimated. Pains
are taken to drop the crowns so that the buds are up. As a rule, in
the large plantings no attempt is made to spread the fleshy roots
uniformly.
Fig. 24. — Hauling asparagus crowns to the field.
Fig. 25. — Dropping the crowns in the trenches. The man in the
foreground carries a sack which holds the crowns.
58
UNIVERSITY OP CALIFORNIA — EXPERIMENT STATION
Covering the Crowns. — This operation should be done if possible
the same day the crowns are planted. The type of soil will determine
to some extent, the depth to cover the crowns immediately after
planting. The best practice is to cover with about 2 or 3 inches of soil.
If the full depth of soil is placed on the crowns immediately after
they are planted, there is danger of smothering the new growth.
The method of covering the crowns varies somewhat. A common
and also an excellent practice is to cover them by hand with a hoe.
Almost any type of horse implement can be used that moves a small
amount of soil free from clods into the trenches.
Fig. 26. — Asparagus bed, intercropped with beans.
Crowns set in field 1923; photo taken July 25, 1924.
As soon as the young plants begin to send sprouts through the
soil covering, more soil is moved into the furrow; this operation is
repeated at intervals throughout the season, so that by midsummer
the fields are usually being given level cultivation.
Cultivation of the Plantation the First Year. — Filling in the
furrows and cultivating between the rows is about all the tillage the
bed needs the first year. The few weeds that appear in the row are
easily smothered by moving soil into the furrow from time to time.
Handling the Plantation during the First Fall and Winter. — It is
best not to cut the top growth until it has been killed by frost. It is
then no longer active in the manufacture of carbohydrates, and the
movement of food to the roots has ceased. There is no longer any
advantage in retaining the top growth unless, as practiced in some
sections, it is left to act as a cover crop throughout the winter.
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 59
Replanting. — The time to locate the missing plants is in late fall,
before the tops are cut. The field should be gone over carefully, and
holes dug where crowns are missing. The replanting may be done
any time during late fall, winter, or early spring.
Intercropping. — It is a very common practice to intercrop the
asparagus beds the first year. For this purpose beans are usually
employed. Other crops sometimes used are potatoes, carrots, peas,
peppers, early cabbage, radishes, and lettuce. Asparagus should not
be intercropped with plants that grow tall and produce a large amount
or shade or that twine about the asparagus tops and smother them.
A number of successful growers regard intercropping as inadvis-
able. They believe that intercrops do not permit clean cultivation
close to the asparagus plants and that they use soil nutrients needed
by the asparagus. In many cases intercropping the first year is an
economic necessity, tiding the grower over until the asparagus fields
come into bearing.
MANAGEMENT OF THE ASPARAGUS PLANTATION THE SECOND
AND SUBSEQUENT YEARS
The methods of handling the asparagus plantation after the first
year vary in the different countries and districts and even on adjoin-
ing farms in the same district. While management can be discussed
only in a general way, there are usually certain major operations
practiced alike by almost all the growers in the same locality. Often
certain practices are followed mainly because of established precedent,
but more often these have been evolved to meet the cultural require-
ments of the region.
In France. — The asparagus fields in the Argenteuil district of
France are not cut until the spring of the third year, and even then
the cutting is light. Each fall, usually in October, the mature stalks
are cut, the soil removed from the mounds, leaving but a few inches
of soil covering the crowns. Eacji spring, usually in March, the soil is
hilled over the crowns again. The third, fourth and fifth years the
mounds are made approximately 7, 9, and 11 inches high, respectively.
They are made higher and wider as the beds become older. It will be
recalled that the asparagus crown tends to grow upward, and to spread
laterally as it ages. Only two or three spears are cut from each crown
the third year. The fourth year, however, harvesting may continue for
three weeks. The fifth year cutting may last from four to six weeks.
After this the fields are usually cut the entire season of seven to eight
60 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
weeks. Harvesting usually starts in early April and ends the fore
part of June. On light soils the profitable life of a bed is about ten
years; on heavy and rich soil it may be more than twenty years. It
is the experience in France that after an asparagus bed is plowed up
the land should not be replanted to this crop for twenty-five or thirty
years.
In the Eastern and Middle Western States. — In the eastern and
middle western states, harvesting is seldom done until the third year.
In South Carolina and contiguous states, however, which have a longer
growing season than the states northward, some fields are cut the
second year. Those beds not cut the second year are handled as
during the first. Some growers burn the dry stalks in late fall, but
in many districts the stalks are left standing over the winter to hold
the snow and prevent the blowing of the soil. Burning the stalks is
not to be recommended especially on mineral soils that are low in
organic matter. In early spring when the soil is sufficiently dry, the
stalks are disked or plowed under. The method of disposing of the
stalks is usually the same throughout the life of the bed. The third
year the fields are cut for a period of two to four weeks, depending
upon the vigor of the crowns. In the green " grass" districts, level
cultivation is usually given. In some parts of Maryland, Delaware,
and New Jersey, where asparagus is still blanched for the market,
the ridges are made by the use of cultivators, disks, or plows, and
other specially constructed implements. As these ridges are lowered
during the harvesting season by the rain and the cutting operations,
they are rebuilt from time to time. At the close of the cutting season
the ridges are disked or plowed down and level cultivation is given
during the remainder of the season. During the fourth and subsequent
years, the beds are handled in much the same way as during the third
year, except that the cutting season is more extended.
In Imperial Valley, California, — In the Imperial Valley, some
harvesting can be done the second year, if the plants have made a
good growth the previous season. The third and subsequent years
the beds are usually cut the entire season. It is the custom to disk
the stalks into the soil during December or early January.
Almost all of the asparagus in the Imperial Valley is grown for
the early market, and if the ridges are high, the soil about the crown
buds warms up slowly, early growth is delayed, and it takes longer
for the spear to grow through the deep covering of soil and attain
marketable length. There is also danger of the heads opening
before the desired length of green is obtained. The usual height of
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 61
the ridge is 3 or 4 inches. The ridges over the rows, however, should
be made sufficiently high to prevent flooding at time of irrigation.
Water is applied early in January. If the soil is warm, this early
irrigation forces the buds into growth. Frequent irrigations are given
during the cutting season. At any one irrigation, water is applied to
alternate furrows, the unirrigated middles being used as walks for
the cutters. At the following application, water is turned into the
furrows not irrigated the preceding time. Frequent irrigation is
necessary in the Imperial Valley, as the evaporation rate is very high
and there is almost no rainfall throughout the year. Cutting usually
starts early in February and continues until shipping is no longer
profitable. This is usually about April 15 but may be as late as May 1.
At the close of the cutting season, the ridges are disked down to
destroy weeds and loosen the soil, but are again rebuilt to facilitate
irrigation and to prevent flooding and the formation of a crust over
the row. It is desirable to secure a good growth of tops as soon as
possible after the cutting season. This growth is usually obtained by
applying a top dressing of 75 to 100 pounds per acre of nitrate of
soda or sulfate of ammonia and then irrigating. The extremely hot
weather during July and August checks new growth, but water should
be applied in order to keep the stalks green so that the manufacture
of food may continue. Cultivation is necessary after each irrigation.
After late August or early September, irrigation is discontinued in
order that additional buds may not be forced into growth during the
fall and thus use the food reserves stored in the roots.
A few growers in the Imperial Valley are now cutting asparagus
in the fall of the year. The fields are matured early by withholding
water. Then the stalks are cut, dried, and burned, or disked into the
soil and water applied to start the buds into growth. The plants have
an exceptionally long period for growth and food storage in the
Imperial Valley. For this reason, it may be possible to develop
methods of handling so that the same beds may be cut for a short time
in both the spring and fall of the year when the returns are most
favorable. However, there are indications that spring cutting is
delayed on beds that have been cut in the fall.
In Delta Region, California. — The methods of handling asparagus
plantations in the California Delta are many, and some of them
unique. It is the general practice to cut the fields the second year
throughout a part or all of the green "grass" season, unless for some
reason there was only a poor growth the previous year. During the
third year cutting may continue until July if the beds do not show
62
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
signs of exhaustion. In the late fall after the tops have been killed
by frost, they are cut with a mowing machine, and when sufficiently
dry are burned. On the light peat and muck soils the tops cannot be
burned until after the surface soil has been well wetted from rain
as there is danger of the soil burning also. A low ridge of soil is
then thrown over the row by use of a disk to cover the stubble and
facilitate its decomposition during the winter.
In the late fall or winter, the soil between the rows is sometimes
subsoiled to a depth of 12 to 15 inches. This aerates the soil, facilitates
Fig. 27. — Eidging asparagus with a disk.
the percolation of water through it, and causes it to warm up quickly
the following spring. Although the subsoilers are run midway
between the two rows, some of the fleshy roots are destroyed. It is
not known definitely whether the advantages accruing from subsoiling
more than compensate for this injury to the roots.
The first operation in preparation for the cutting season is usually
the disking of the soil from the rows. This cuts off the bases of the
stalks and loosens the soil over the crown. A low ridge is then thrown
back over the row. The ridges for green asparagus are made from
4 to 6 inches high. Usually two disking operations are required.
A chain is sometimes dragged after the disk to break the clods and
smooth the ridge. A harrow or flexible board float made to conform
to the shape of the ridge is sometimes pulled behind the disk (fig. 28).
After disking, a ridge harrow is often used alone or in combination
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
63
with a wooden float. In the older beds, a higher and wider ridge is
required than in the younger ones. During the green "grass" season,
cultivation is mainly between the rows.
Preparatory to cutting white asparagus for canning, the low ridges
are usually disked down. Though a large number of young spears are
destroyed, it is probably the only profitable method that can be
employed to kill the weeds and loosen the soil. The ridges are
immediately rebuilt and are made much higher than when green
asparagus is cut. Each ridge is made 15 to 20 inches high, depending
upon the age of the bed. The ridges are made higher each year in
Fig. 28. — A board float is often attached behind the disks.
order to get the desired length of spear, and to prevent injury to the
crown in cutting. They must also be made wider each year, as the
spread of the crown increases. During the cutting season for the
cannery, the beds must be rebuilt every few weeks. At the end of
the cutting season they are disked down and the fields are given level
cultivation the remainder of the growing season. The middles between
the rows are worked constantly during and after the cutting season
with disks, cultivators, drags, and floats. When the "fern" appears,
hand hoeing, as well as cultivation, is employed. On some farms
horses are used almost entirely, while on others tractors are used
whenever possible.
It is on the reclaimed lands of the Delta that most of the asparagus
in California is grown. Not many years ago the overflow delta lands
were growing little else than the marsh "tule" (mainly, Scirpus
64 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
lacustris var. occidentalis) . The growth of vegetation and the decom-
position and accumulation of organic matter throughout the centuries
have built up one of the most productive and fertile soils that can be
found anywhere in the world. Formerly, nearly all of the Delta
land was subject to inundation. Enterprising capital, however, has
built large levees and confined the one-time meandering streams and
flood waters to well defined channels ; at present almost all of the land
is protected from overflow. Generally, the level of the asparagus land
is below that of the water in the streams, and irrigation is carried on
by siphoning and pumping the water from the rivers and network of
waterways that surround the islands into large ditches that carry it to a
system of laterals throughout the fields. The soil is open and porous,
and when the water is raised in the ditches the water table is elevated
throughout the entire soil area. The water is raised to within a few
inches of the surface and is then pumped back into the river until
the water level of the land reaches the desired depth, which is usually
from 4 to 6 feet. The time of irrigation and the number of irrigations
given vary with conditions. If rainfall during the winter has been
light, then irrigation will necessarily start earlier in the spring than
if the soil had been well wetted by a heavy rainfall. It is occasionally
necessary to stop irrigation early in the summer especially after
seasons of drought similar to the one experienced during the winter
of 1923-24; for when there is not sufficient fresh water supplied by
the melting snow in the Sierra Nevadas, the brackish water from
Suisun Bay moves up the streams for a considerable distance.
In the lower Delta near Suisun Bay, there is a difference of several
feet between high and low tide. This makes it possible to irrigate at
high tide and drain the land at low tide. At high tide the flcod gates
are opened and the water is run into large irrigation ditches. When
sufficient water has been added, the gates are closed. When irrigation
is complete, at low tide the gates on the levees are again opened and
the water drained off. It takes some time to lower the water table
in the soil after irrigation. The minus tides are not always sufficiently
low to give the desired depth of water table, so some water is pumped
back into the stream. In this region, in seasons of normal rainfall,
irrigation must stop some time in July because of the high salt content
of the water; in seasons of low rainfall, irrigation usually stops
somewhat earlier.
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 65
FACTORS INFLUENCING THE YIELD OF ASPARAGUS
The yield of asparagus from a plantation, considered for any one
year or for a series of years, is influenced by a number of factors,
chief of which are : age of crown, temperature, fertility of the soil,
cultural methods, moisture, variety, fungous diseases and insect
enemies, size of crown at the time of planting, and sex of plants. All
except the first two — age of crown and temperature — are discussed
elsewhere in this bulletin.
Age of Crown. — The yield of an asparagus bed gradually increases
until the seventh or eighth year, after which there is usually a gradual
decline. The average production per acre in California over a period
of eleven years is given below.
Yield per acre
Year (pounds)
First (year planted)
Second 500
Third 1,000
Fourth 2,000
Fifth 4,000
Sixth 4,250
Seventh 4,500
Eighth 5,000
Ninth..., 5,000
Tenth 4,750
Eleventh 4,500
Total 35,000
Loisel (14) gives the annual production per acre at Chen-Saint
Florentin (France) as follows:
Fourth year 2,300 pounds
Fifth to twelfth year 3,100 pounds per year
Thirteenth, fourteenth and fifteenth years, average 2,375 pounds per year
At Cherburg (France) he gives the following annual production
per acre :
Fourth year 1,750 to 2,375 pounds
Fifth to twelfth year 3,170 to 3,300 pounds per year
Thirteenth, fourteenth and fifteenth years, average. ...2,640 pounds per year
Total yield for period 35,030 to 36,697 pounds
The probable life of an asparagus bed is a factor of considerable
economic importance. When profitable production from a large
plantation of this kind ceases, it often imposes a considerable reorgan-
66 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
ization of farming operations. Consequently, the addition of a year
or two to the profitable life of a bed is very significant.
Reference to the literature shows that the average life of a com-
mercial planting, during which period the yields are profitable, is
from 10 to 16 years.
Loisel (14) says that in light soil a bed lasts no longer than 10 years,
but that in heavier and rich soils it may last more than 20 years. He
further points out that when such a bed is exhausted, asparagus
should not be set out in the same place for 25 to 30 years.
In the Delta region of California, the beds in peat soil are shorter
lived than those growing in sediment.
Ilott (12) cites a case of "some beds in a grand old garden of
Devonshire which had a history of at least 90 years, and in Cornwall
I know a bed, the proprietor of which is probably 40 years of age,
this bed having been planted by his father before the present owner
was born, and yet it produces splendid shoots."
The Causes of Aging of the Crowns. — Various explanations have
been offered to account for the' "running out" of an asparagus bed.
Chief of these are the exhaustion of the soils and the elevation of the
crowns.
Exhaustion of the Soil. — It is well known that every plant takes
from the soil quantities of mineral elements, and that any particular
kind of plant has its own peculiar mineral requirements. Reference to
pages 36 and 37 will show the mineral nutrients removed from the soil
by an asparagus crop. It will be observed from these data that of the
three principal nutrient requirements (nitrogen, phosphoric acid, and
potash), the demands are relatively great for nitrogen and potash.
One would naturally reason that if exhaustion of the essential mineral
compounds from the soil were the cause of the deterioration in the
asparagus bed, then the yearly application of these ingredients in the
form of manure or commercial fertilizer, or both, would maintain
the yield. It appears, however, that the proper application of fer-
tilizers increases the yields on certain types of soils, but the profitable
life of the bed is not materially lengthened.
The root system of an asparagus plant, even at the end of the
sixth year, is extensive and forms a very compact mass. As shown on
page 17, a six-year-old crown bore 1,012 fleshy roots with a total
estimated length of 3,414 feet. Most of these roots occupied a soil
volume of approximately 108 cubic feet. When one digs a root system
of this age or older, he is impressed with the fact that the roots
actually do occupy a very large proportion of the space in which
BuL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 67
they are growing, and it is immediately suggested that a condition
similar to that of a "root-bound" potted plant is being approximated.
Possibly, deterioration of asparagus with age is in part due to this
condition. If this is true, one would expect a bed with plants set far
apart to have a longer life duration than one in which the plants are
crowded.
Elevation of the Crown. — It is well known that the asparagus
crown grows toward the ground surface. As the bed grows older,
the shoots arise from higher and higher levels. It was formerly the
practice in some sections to plant the crowns as deep as 18 inches,
believing that by so doing the life of the bed would be prolonged.
The assumption was that deterioration was due, at least in part, to
crown elevation, and that deep planting, therefore, would make pro-
duction profitable over a longer period. This practice of extremely
deep planting has been largely given up, because the crop harvested
from deep planted crowns is late and the rate of elevation the first
few years of a deeply planted crown is much greater than of one
planted shallower. While the branches of a crown planted at the
usual depth of 10 or 12 inches grow diagonally toward the surface,
those of one planted at a depth of 18 inches or more grow almost
vertically for the first few years, or until such time that they attain
a certain level. Consequently, the supposed advantages of very deep
planting are overcome after a few years.
The larger spears develop from buds at the end of the rhizome.
The smaller spears usually come from buds that have been dormant
along the sides of the main rhizome. As the branches come near the
surface, many of the terminal buds are destroyed by cultivation, thus
forcing the lateral buds into growth. This probably accounts, at least
in part, for the great increase in the number of spindly shoots as the
beds become older.
It must be admitted that there are no reliable experimental data
relative to the factors causing the "running out" of the asparagus
plantation. All of the factors mentioned above may play a part. To
these should be added that of senility, about which little is known,
however. Individual plants, as well as animals, grow old. They pass
through a period of productivity, after which there is a decline. The
decline is probably due to inherent internal factors, as well as to
external ones.
68 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
VARIETIES
Early Mention of Asparagus Varieties. — In Greek and Roman
times, it appears that a distinction was made between "wild
asparagus ' r and ' ' cultivated asparagus. ' ' The wild asparagus of the
Greeks was known as orminos and myacanthos, and by the Romans
as corruda. It is quite probable that the only differences between these
two were such as were due to garden care. Cato speaks of the
asparagus which grew spontaneously upon the island of Nesis, off the
coast of Campania, as being the best of all. Further, the asparagus
from the gardens of Ravenna was extolled for its high quality, though
Martial says that it was no better than so much wild asparagus.
These statements probably indicate that there was at that time no
markedly distinct cultural varieties of asparagus.
Origin of the Holland and Argenteuil Varieties. — It was not
until the l$th century that important progress was made in the
improvement of cultivated asparagus. Early in this century there
originated the "violet asparagus of Holland," Purple Holland or
Purple Dutch, a variety supposedly producing much larger spears
than had been grown before. From this Holland variety, there were
obtained from seedling selections the two well-known Argenteuil
varieties, Late Argenteuil and Early Argenteuil. The Late Argen-
teuil was originated in 1860 by Lherault-Solboeuf, an asparagus
grower at Argenteuil, France. The Early Argenteuil was developed
in 1862 by Louis Lherault, also an asparagus grower at Argenteuil.
Present Day Varieties of Asparagus in the United States. — It is
recognized that many of the so-called varieties of asparagus differ
but little. The same variety may present characters sufficiently
different when grown under widely different environmental conditions
to suggest distinct varietal names.
Conover's Colossal (Van Sicklen, Colossal). — This variety origi-
nated with Abraham Van Sicklen of Long Island, New York, and was
introduced by S. B. Conover, a commission merchant of West Wash-
ington Market, New York City, about 1882. It is the oldest known
American variety. It is now being superseded by other more rust
resistant varieties like the Palmetto and the Washington strains.
Palmetto. — This variety was introduced by Peter Henderson &
Company of New York, N. Y., in 1886. It originated on a farm in
South Carolina. The particular advantages of Palmetto are its resist-
ance to rust and its productivity.
BlJL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 69
Columbian Mammoth White. — This variety was introduced by D.
M. Ferry & Company of Detroit, Michigan, in 1893. "It was the
result of patient work and careful selection of the progeny of a single
plant having white shoots found growing in a field of Conover's
Colossal. Seed was sown from this plant, a small percentage of which
came true, and these were planted by themselves and seed from them
saved. This process was continued for a period of fourteen years
preceding the dates of introduction. At the present time only a
relatively small percentage of seeds produced green plants."
(Myers. (17) ) This variety is characterized by its large shoots, which
remain a clear white until 3 or 4 inches above ground.
Reading Giant. — This is an old variety of English origin. It was
formerly grown to a considerable extent in the eastern states.
Washington Varieties. — The Washington varieties are very promi-
nent and promising American sorts. The history of these is described
by J. B. Norton (18) :
"Varieties from all over the world were collected at Concord,
Mass., and subjected to rust-epidemic conditions. Not one plant was
found to be completely immune to rust. However, selections were
made in 1908 from the most resistant ones and pedigreed seed pro-
duced in 1909. The lots of seedlings grown in 1910 showed one male,
A7-83, from a lot of New American of unknown origin, to be a won-
derful plant in transmitting vigor and rust resistance to the progeny.
A female plant, B32-39, from Reading Giant, procured from Sutton &
Sons, Reading, England, when crossed with this male gave the best
progeny lot of all the hundreds of combinations. From this pair came
our first -named strain, Martha Washington.
' ■ The male plant, Washington, and the female plant, Martha, with
other female plants, have since been removed to the Arlington Experi-
mental Farm, near Washington, D. C, the crowns being separated
into several divisions and planted in an isolated bed for breeding
purposes. Several new female plants have been added from time to
time as they have shown their value as producers of good seedlings.
Notable among these is the giant female taken as a seedling from a
bed of Reading Giant grown by Mr. C. W. Prescott, at Concord, Mass.,
in 1910. This plant has been named Mary, and in combination with
the male plant, Washington, gives our newest named strain, Mary
Washington. "
In Mary Washington, Norton has produced a variety that is much
more uniform in size, shape, and color than any of the older varieties.
The Washington varieties are replacing the older ones in almost all
70 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
asparagus regions which are subject to severe rust epidemics, and also
in some asparagus sections where the rust is almost unknown. In the
northeastern states the growers favor the Martha Washington, but in
most other sections the Mary Washington is the more popular of the
two.
Almost all asparagus varieties can be placed in two groups accord-
ing to the color of the spears : The varieties with light green spears,
of which Conover's Colossal is most representative; before they are
exposed to the light the spears have a violet or reddish tip. The
varieties with dark green spears and a purplish overcast; these
varieties are purple tipped before they are exposed to the light.
Observation seems to show that Palmetto and Argenteuil are very
nearly identical. Some growers claim that Palmetto has spears of a
deeper purple color, is longer lived, and is more productive than
Argenteuil; other growers claim just the opposite. Differences
between the two appear to be due to soil and climatic conditions and
to methods of selection. So far as is known, no pedigree work has
been done on the Argenteuil or Palmetto varieties comparable with
that done by Norton on Mary Washington.
SEED PRODUCTION AND METHODS OF IMPROVEMENT
Seed Selection. — It is well recognized by all asparagus growers that
large, plump, glossy, and fully matured seed is superior to small,
shrivelled, dull, and immature seed. However, the methods of grow-
ing asparagus seed of high quality have not been given the attention
that they deserve.
Age of Plant from Which to Select Seed. — There is a diversity of
opinion among growers as to what the ages of plants should be in
order to yield seed of the best quality. The statement is made by some
that plants must be "not less than four years old" before they have
sufficient maturity and vigor to produce seed of high quality. Other
growers state that seed should be harvested only from plants the
crowns of which were planted the previous year. Plants of this age,
it is reasoned, have not been " weakened' ' by the harvesting of sprouts
during the current year as have the older plants; "consequently, it
has been possible for more energy to be directed to the production of
seed." It is a common practice on California asparagus farms to cut
market asparagus for a period of about three or four weeks the first
year after transplanting ; whereas, in older beds, the cutting season is
for a much longer period. Hence, in the former case, there is a longer
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 71
season of growth after the cutting period than in the older beds. It
is reasoned that seed from plants which have been cut for a few
weeks only will have a better opportunity to fill out and mature. It
should be stated also that by taking seed from young asparagus beds
rather than from old ones, the grower has a better opportunity to make
rapid improvement in his varieties. Other growers claim that there
is no correlation between the age of the mother plant and the vigor of
the seed it produces.
Unfortunately, there are no reliable experimental data which will
enable us to discuss authoritatively the three views presented above
and to make a definite recommendation as to the best age of plants
from which to select seed.
Quality of Seed from Different Parts of the Plant. — Some hold the
opinion that seeds borne on different parts of the same plant vary in
quality. It is stated that the best seed is procured from the lower
part of the plant and that consequently it is advisable to top it by
removing from 8 to 12 inches, after the basal flowers have been
fertilized. The first flowers to open and the first berries to form are
on the main shoot near the base of the plant ; and on the whole plant,
or on any one branch, the order of maturing of berries is from the base
to the apex. At the tips of the branches, then, there may be at harvest
time a considerable number of berries which are not so well developed
as those farther down on the branches and, consequently, the har-
vested seed may contain a certain percentage of seed from relatively
immature berries. It is believed that this condition can be obviated by
cutting back the tops after the basal flowers have been fertilized. It is
also asserted that topping the plants leaves more nourishment avail-
able for the remaining seeds, and that they will thereby become larger
and produce more vigorous seedlings.
Since no carefully conducted tests have been made to ascertain the
value of the practice of cutting back the tops of seed-bearing plants,
the authors are not in a position either to recommend or to discourage
this practice. Careful screening and grading, however, should elimi-
nate the smaller and less mature seeds which are borne near the tops
of the branches. Grading is suggested as being a possible and
desirable substitute for topping.
Methods of Handling for Seed Production. — The commercial
grower who is producing his own seed should observe some of the
fundamental principles of selection. In most of our crops, both male
and female reproductive organs occur on the same plant and usually
in the same flower, but each asparagus plant we have seen is
72 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
almost always of one sex only. It is as important to choose the best
male plants as it is to select productive, healthy, and otherwise
desirable types of female plants. In the past, practically the only
method of seed selection used by the growers themselves has been to
go through the fields in the fall of the year when the seeds are mature
and harvest the seed from the desirable seed-bearing plants. The chief
weakness of this method is that the female parent only is selected.
The flowers of these female plants may have been pollinated by
inferior or mediocre male plants.
The improvement of asparagus by seed selection is an attractive
undertaking and will prove profitable if done properly. Several
methods are given below.
Method 1. — Records of the performance of certain promising indi-
vidual crowns should be kept over a period of several years, The
crowns of the most desirable male and female plants should be dug
and set together in a bed that is isolated. One male plant to about
five or six females is sufficient. It is best to group the female plants
about the male. The desirable female plants will be pollinated only
by the selected male or males.
Method 2. — In the commercial field, a number of the most desir-
able male and female individual plants should be marked in the ratio
of approximately one male to five or six females. These individuals
should be allowed to mature before the main crop, so that pollination
is only between the individuals selected. This method, however, is
not practicable in regions where the ridges are disked or plowed down
periodically to loosen the soil and destroy the weed growth.
Method 3. — A small isolated acreage should be set aside for seed
production only. At the beginning of the blossoming period the
grower should grub out weak and undesirable types of male plants.
If they are left in the field, pollen from them may be carried to the
flowers of the selected female plants and the undesirable characters
of the inferior males transmitted to the progeny of the superior
females. Seed from the superior females only should be harvested.
It is unnecessary to grub out the inferior females, the seed of which
should not be harvested.
In careful breeding work, however, hand pollination is necessary
if the best results are to be obtained. Even when plants are isolated
it is not always safe to conclude that foreign pollen has not been
introduced.
Open Pollination. — Regarding open pollination, Norton states that
"the insect visitors to the asparagus flowers are largely bees of
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 73
different kinds. The honey bee is most plentiful during the blooming
season, and at this time of the year practically all of the pollen that
comes into hives that are near the asparagus fields is the rich, orange
pollen from the staminate asparagus flowers. Apparently a large
amount of nectar is also produced. This is shown particularly in
flowers under bags where the bees have been kept away until the
flower is old, when it is so abundant as to interfere with pollination.
Some of these small bees are a nuisance in the pollination work,
apparently being especially attracted by the extra quantity of honey
in the protected flowers.
"The wind seems to play little part in pollination, as the male
flowers retain their load of pollen until they begin to wither, unless
it is removed by a bee. The pollen hangs together in masses and does
not become powdery until the flower dries up."
Testing of Progeny. — The progeny of the various crosses and
selections should be tested under field conditions ; only those com-
binations giving desirable offspring should be retained for future
breeding.
Desirable Types to Select for Breeding Purposes. — As much care
should be given to the selection of the male as to the female parent.
The plants should be heavy producers throughout the cutting season
and over a long period of years. The spears should not bulge just
below the surface of the soil; they should have a gradual taper from
butt to tip. The leaves or scales should fit snugly against the stem
and should remain compressed against it for some time after coming
through the soil. The color should be a dark green with a purple over-
cast. The dark green varieties appear to be more rust resistant than
those that are of a lighter color.
Selection of the plants for breeding purposes after the stalks have
become fully developed is not as desirable as selection during the
cutting season. Plants with high-branching stalks produce spears
that hold the scale leaves close for a time. It is better to select plants
that have a medium number of large healthy stalks than those that
have a large number of small stalks. Some authors state that those
pistillate plants which bear much seed are not as vigorous or as heavy
yielders of marketable spears as those which produce few seeds. They,
therefore, recommend using for breeding purposes pistillate plants
that do not naturally produce a large number of flowers. So far as is
known, no experiments have been conducted to test this theory.
Harvesting and Grading Seed. — If the berries are harvested before
they are mature, the seed shrivel to some extent. At maturity the
74 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
selected seed-bearing plants are cut and laid on canvas, and the
berries may be placed in burlap sacks and pounded or tramped in
order to break the berry coats and free the seed. This mass of
material is then placed in a barrel or tank of water and stirred well.
The seeds settle to the bottom and the lighter material, such as skins,
pulp, and stems, rise to the surface, where they are skimmed or floated
off. After several changes of water, the seed should be spread out on
a canvas to dry.
After the seed is dried, it should be run over properly meshed
screens and graded as to size. The practice of grading is strongly
recommended.
There is much variation in the weight and number of seed to the
pound in different lots of commercial asparagus seed. Certain lots of
seed contain as many as 28,000 seeds to the pound, while others have
approximately 19,000 seeds. The average run of commercial seed,
however, has about 22,000 seeds to the pound. It is well known that
Mary Washington seeds are of larger size than those of any other
variety, which favors early seedling development and large one-year-
old crowns. There are a number of factors which influence the size
of seed, but most lots of seed may be improved by careful grading.
Seed Storage and Viability. — Asparagus seed should be stored in
a cool, dry place. Under proper storage conditions it will maintain
its viability for four or five years. However, it is best to plant fresh
seed, as it germinates more quickly than old seed.
FRESH ASPARAGUS FROM THE FIELD TO MARKET
Fresh asparagus may be sold with the spears entirely blanched,
almost entirely blanched (green tip), green throughout except for
white butts, or entirely green. White asparagus is produced by growth
in the dark. When exposed to the light the spears become green because
of the development of the chlorophyll pigment. The longer the time the
spears are permitted to grow above ground before cutting, the greater
will be the percentage of green on the harvested product. In Europe,
nearly all of the asparagus sold in the fresh condition is white. In
some parts of the east asparagus beetles do considerable damage to
the spears after they appear above ground; hilling and cutting the
white product, therefore, greatly reduce the loss from injury. The
greatest demand in this country at present is for the green product,
and the demand for this type is constantly becoming greater. Most
of the asparagus districts in the United States ship the green product.
BlIL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 75
A white butt is desired by most shippers as they claim the spears
wilt less than when green and tender throughout. In the Delta most
of the asparagus is cut for the market before April 10. Some growers,
however, cut during the entire season, that is, up to about July 1, to
supply the local markets. In the Imperial Valley, the aim is to
terminate the main shipping season, prior to the appearance of large
quantities of asparagus grown nearer the main consuming centers.
When harvesting commences in the east and middle west, long dis-
tance shipments may be fewer, though California asparagus is often
sold profitably in competition with early receipts from the Carolinas
and Georgia,
Cutting. — The manner of cutting asparagus varies considerably in
different sections. According to Loisel, (14) two methods of harvesting
are used in France : In the small gardens the soil is removed to some
depth and the spear is given a twist, which severs it at its points of
attachment to the crown. When the spears have been removed, the
mound is again rebuilt. The method is fairly rapid in working with
the lighter types of soil. It also has the advantage of causing no
injury to the young spears which are not in sight. The more common
method is to cut the spears with a gouge knife very similar to the fish-
tailed and chisel-shaped asparagus knives used in this country.
In the Imperial Valley an effort is made to secure as much green
as possible and still have spears with closed heads that will carry
well to the eastern and middle western markets. Only a low ridge
is made over the asparagus row to mark it and prevent flooding at
time of irrigation.
In the California Delta, the spears are cut when they are 3 to 4
inches above ground. There is constant danger of frost during the
early season; in order to prevent a great deal of loss, therefore, the
asparagus is usually cut with less green than is the practice in most
of the other green "grass" districts.
At the beginning of the season when the harvest is light, the
cutters carry the spears in containers and place them in lug boxes at
the ends of the rows. When production becomes heavier, however, the
asparagus is laid on the tops of the ridges, the harvest from six to
eight rows usually being laid on the two center ridges.
In the Delta the cutters are usually in the field at daybreak.
Cuttings are made whenever the spears are sufficiently long ; this may
necessitate harvesting each day, or every second or third day. Cutting
continues until all the fields have been gone over. In the San Fernando
Valley of California and in some sections of the Middle West the fields
76 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
are often cut twice in a day, especially on light sandy loam soils after
a warm rain and following hot nights. On heavy clay soils, the growth
is often so slow that cuttings are made but once or twice a week.
Hauling. — The cut spears which have been laid on the ridges are
gathered and placed in a horse-drawn sled or cart (fig. 29). If the
packing is to be done in the field, the spears are usually stacked loosely
in the body of the cart, with the heads touching the sloping front. If
the packing is to be done at a distance from the field, the asparagus
is usually placed in lug boxes. These are then stacked at the ends of
Fig. 29. — Cart used in hauling asparagus from the field to the washing shed.
the rows or are placed on loading platforms, from which they are
hauled by auto trucks directly to the packing sheds or to the wharves
and later taken to the packing sheds by boat.
Types of Pack. — Fresh asparagus may be packed loose in the
crate or bunched. The loose pack may include the ordinary ungraded
field run of asparagus or only the spears that are difficult to bunch.
The Loose Pack. — Shippers of loose-pack asparagus usually have
their own packing sheds in the field, and the asparagus is hauled
directly from the field into the shed. The spears are laid straight in a
form about 3 feet wide, 2 to 3 feet high, and about 10 inches deep (fig.
30). The tips rest against the back wall of the form. A board moving
vertically in a slot is pressed down and locked to hold the spears
firmly in place. These are then trimmed to a uniform length with a
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
77
large knife, which is usually made from an old cross-cut saw. The
spears are trimmed to a length of 9 or 10 inches or less.
After trimming, the spears are laid loose in pyramid-shaped crates
without partitions (fig. 31). Oiled paper is placed on the bottom and
two sides of the box. On the paper in the bottom of the box is placed
a layer of wet moss. Then, a thin galvanized tin sheet, or wooden
panel, having the dimensions of the bottom of the box and equipped
Fig. 30. — Trimming asparagus in the field shed.
with a handle, is laid on top of the moss. During packing, the crate
is laid on its side. After the box has been filled, the tin sheet is
jerked out, leaving the asparagus butts resting upon the wet moss. The
oiled paper is then folded over the asparagus on the open side and
the side boards nailed on. Sufficient asparagus is placed in the box
to give a good bulge; this prevents movement of spears within the
container and holds the pack firm even if the spears become slightly
wilted.
Bunched Asparagus. — By far the greater proportion of asparagus
which is shipped to the markets is first carefully graded, then bunched,
78
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
trimmed, wrapped and packed. Well-equipped packing houses are
provided for these operations, and some of the larger employ several
hundred workers during the height of the shipping season.
Sorting and Grading. — Asparagus is brought to the packing shed
usually in 50 or 60-pound lug boxes. Here the spears are laid on
tables and sorted by hand into different grades. California shippers
usually pack four or five different grades, which are distinguished
mainly on the basis of size. In addition to these there is another grade
Avhich includes all spears too crooked to fit in the bunch and those
Fig. 31. — This shows the manner of making the loose pack.
that are not green enough. These are not bunched, but are packed
loose, usually in 50 or 60-pound lug boxes or pyramidal crates, and
nearly always shipped to the local markets only.
The following grades and specifications for asparagus have been
adopted by the Bureau of Agricultural Economics of the United States
Department of Agriculture :
I J. S. Grade No. 1 shall consist of clean, fresh stalks of asparagus
which are not wilted or crooked, which do not show broken or spread-
ing tips, and which are free from damage caused by disease, insects,
or mechanical means. (As used in U. S. Grade No. 1 and No. 2, "free
from damage" means that the asparagus shall not be injured to an
extent readily apparent upon examination.) In order to allow for
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
79
variations incident to proper grading and handling, not more than
10 per cent, by count, of any lot may be below the requirements of
this grade but not to exceed one-half of this tolerance shall be allowed
for any one defect.
U. S. Grade No. 2 shall consist of stalks which do not meet the
requirements of the foregoing grade.
Fig. 32. — One type of asparagus buncher. Other types are in the market.
Fig. 33. — Five common grades of green asparagus. From left to right:
Colossal, Extra Selected, Extra Fancy, Fancy, and Choice.
In addition to the statement of grade, any lot of asparagus may
be classified as Small, Medium, or Large, if 80 per cent, by count, of
the stalks in any lot conform to the following requirements for such
Vie to % inch diameter; Large,
sizes: Small, % to % 6 inch; Medium, °
over % inch. The foregoing measurements refer to the diameter of
the spears measured at a point not more than 8 inches from the tip.
80
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Bunching. — The different grades of spears are tied in bunches,
each weighing approximately 2% pounds. When placing the spears
in the buncher, care is exercised to have the top of the bunch even
and the curved tips pointing inward. The bunches are bound tightly
by hand near the base and tip. The tape used generally comes on
1,000-foot spools, is ^-inch wide, and before using is run onto a
cylinder and then cut into 18-inch lengths. Different colors of tapes
are often used to designate the various grades.
There are sometimes complaints on the eastern markets that the
bunches are loose when they arrive. This condition may be due to
Fig. 34. — Green asparagus, bunched and ready for shipment.
high temperatures which increase transpiration and cause a pro-
nounced wilting of the spears. However, there are instances where
bunches reach the market in a loose condition, and yet the individual
spears are still turgid. This is due to the following conditions : Early
in the season when the weather is cool and moist, the asparagus shoots
brought in from the field in the early morning are very turgid. If
they are bunched in this condition, it is difficult to obtain a snug fit
of spears in the bunch. Although the bunch may be firmly tied, the
necessary handling and jostling in packing and shipping, together
with even a slight loss of water, brings about a readjustment of the
position of the spears in the bunch. If the spears are bunched when
they are slightly wilted and pliable, a tight pack can be secured ; and
they are not so easily broken when being tied. When these bunches
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 81
are later stood on moist moss they absorb water, become slightly more
turgid, and remain so.
Trimming. — After they are tied, the bunches are trimmed to a
uniform length, usually of 8 1 /*? inches. Trimming is done by hand
with the aid of a long-bladed knife. The trimmed bunches are
immediately stood in shallow pans in an inch or two of water, which
is usually iced. Here they remain until packed. The trimmed butts
from green asparagus may constiute a waste of 5 to 40 per cent. At
present no use is made of the trimmings.
Packing. — The bunches are removed from the pans and each
wrapped in a parchment paper label, usually measuring about 8 inches
wide and 18 inches long. The tips of the asparagus shoots extend
above the edge of the label. The wrapped bunches are immediately
packed in the pyramidal crates with the butts resting on moist moss.
It is the practice to place parchment paper in the bottom of the box,
so that the moss rests upon this paper, rather than upon the dry
boards of the box. This practice also prevents the rapid evaporation
of water from the moss.
The moss is obtained in bale lots. It is shredded by hand or with
a hair picker operated by man power. About one-half pound of wet
moss is placed in each crate.
When the packer receives the crate it is " mossed" and open on
one side. When packed, the sides are nailed on so that the label of
each bunch is conspicuous and the tips show above the upper strip.
Crates Used for Packing. — Nearly all California asparagus is
shipped in pyramidal crates. It is possible in a crate of this type to
have the bunches standing upright while being shipped. The shape of
the box conforms to the tapering form of the bunches, and, when well
packed, the asparagus has little opportunity to move about. The crate
is divided into two compartments, each holding six 2%-pound bunches.
In the California pyramidal crate, the two end boards are 10%
inches high and % inch thick, 9% inches wide at the top and 11 inches
wide at the bottom ; the partition board is only %g inch thick ; the top,
bottom and side board are % inch thick; the top boards are 4 by
19V2 inches; the bottom boards, 5% by 19% inches; and the sides
(upper) 2 by 19% inches, and (lower) 3% by 19% inches; two cleats
on the top are % by 9% by % inches.
The two compartment pyramidal crate is also used in South
Carolina. In New Jersey, the 32-quart berry crate holding 24 bunches
is used. In Illinois a sectional crate is in use with individual compart-
ments for 24 bunches.
82 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Precooling , Loading, and Refrigeration. — In the early spring
when cuttings are light and before it is possible to obtain a sufficient
number of crates to make carlot shipments, almost all of the asparagus
is shipped by express and without refrigeration. In the Imperial
Valley, as soon as carlot shipments begin, the asparagus is precooled
before it is loaded into iced cars. In Northern California, precooling
is not practiced, the crates being loaded into iced Pacific Fruit
Express cars as soon as packed. The crates are stacked in tiers in
the car and held stationary by bracing. Bunker icing is practiced.
The bunkers are filled with ice several times during transit.
Shipping Seasons. — The shipping season of any locality varies from
year to year. Temperature is the main factor determining the begin-
ning of the harvesting season. California is the first state to start
shipping asparagus in early spring. The Delta region and the Imperial
Valley start shipping about the same time. Asparagus is shipped from
the Imperial Valley until eastern asparagus moves in quantity. This
may be as late as May 1, but is usually about the middle of April.
There is no canning of asparagus in the Imperial Valley or about Los
Angeles. Most of the growers in the Delta stop cutting for shipment
by April 1, or shortly thereafter. Heavy rains in late March or
early April may delay the opening of the canning season. There is
a considerable acreage, however, that is cut for shipment to nearby
markets throughout the season, i.e., until late in June or early in
July. South Carolina and adjoining states usually start shipping
a small quantity of asparagus in less than carlots in March. Most
of the asparagus, however, moves from these states in April and May.
Illinois starts shipping in April and continues throughout the months
of May and June. New Jersey also starts shipping in April, though
the bulk of the crop moves during May and June. New Jersey also
ships a small amount in early July, as does also California and Illinois.
Carlot Shipments.- — Carlot shipments of asparagus by states may
be obtained from the Bureau of Agricultural Economics of the United
States Department of Agriculture. The figures, however, do not show
the amount of asparagus grown near the large consuming centers and
hauled to market by truck. Much asparagus grown in the vicinity of
New York, especially on the New Jersey side, and in the neighborhood
of Boston, Baltimore, Philadelphia, Washington, D. C, Chicago, Los
Angeles, and other large cities is hauled to market by auto trucks and
therefore does not appear in the carlot totals. The apparent gradual
decrease in the amount shipped from New Jersey is due primarily to
the increasing volume being transported by truck.
BUL. 446 J T HE ASPARAGUS INDUSTRY IN CALIFORNIA 83
Most of the carlot shipments in California are from the Delta
region. The grading and packing sometimes is done on the ranches,
but usually it is done in the more densely populated centers where
there is more labor available. Formerly most of the asparagus grown
in the Imperial Valley was shipped to Chicago. The early ship-
ments from the Delta go principally to the large eastern markets.
In March the product is pretty well distributed throughout the
Middle West and East, but when the eastern beds start bearing, the
product from the Delta goes primarily to points in California and
other coastal and Rocky Mountain states. Most of the asparagus
produced in the Los Angeles district is consumed locally.
Changes in the Quality of Asparagus- after Cutting.— Bisson,
Jones, and Robbins (n have shown that changes occur in the structure
and chemical composition of asparagus after it is harvested which
affect its edible qualities. The principal changes concern growth in
length, and weight of dry matter, reducing substances, total sugars,
and crude fiber. These changes are markedly influenced by the
temperature at which the spears are stored.
Asparagus spears grow in length in the crate, if the butts are on
moist moss. If the moss remains moist the chief factor determining
the growth rate is temperature. The growth rate was found to be
least at 33° F, and to increase as the temperature is raised (within
the limits of the experiment). The greatest percentage of increase
in the length of asparagus occurred the first 24 hours, after which
there was a slowing down in the rate. Mold appeared on the asparagus
stored at temperatures of 77° F and 95° F after a few days, and these
samples were therefore discarded.
Asparagus spears stored with their butts in water or on wet moss
absorb water and increase in weight. The rate of weight increase
due to water absorption was least at 33° F, somewhat greater at 41° F,
and still greater at the higher temperatures. Here, again, the highest
percentage of increase in weight occurred the first 24 hours after the
spears were harvested. There is a slight wilting immediately after
harvest, which no doubt accounts to some extent for the rapid increase
in weight during the early storage period.
There is a loss in reducing substances and in total sugars from the
spears at all temperatures. These losses are especially pronounced at
the higher temperatures (56°, 77°, and 95°), the maximum rate of
loss being during the first 24 hours. It should be stated that the sugars
constitute but one group of substances which determine flavor ; among
others may be mentioned esters, glucosides, amino-acids, and proteins.
84 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
The loss of sugars during storage is due to its destruction in respir-
ation, and its transformation to cell wall material, chiefly lignin, and
other substances.
Both microchemical and macrochemical studies showed a general
increase in the number of lignified elements both in the fiber zone and
in the vascular bundles of the spears at all storage temperatures.
Lignification took place the full length of the spear. The percentage
of crude fiber was determined by chemical analysis. The greatest
increase in crude fiber came the first 24 hours after the asparagus was
cut, but was least at the lowest temperature and greatest at the highest
temperature. The amount of crude fiber present is an indication of
the toughness of the spear.
Green asparagus should be bunched and packed as soon after
harvest as is compatible with efficient handling. It should then be
placed and held at a temperature slightly above the freezing point.
Even at this low temperature there is some deterioration as shown in
the reduction in sugar and increase in fiber. It is desirable that the
product reach the consumer in the shortest possible time. It is
advised that the crate, and the parchment wrapper about the indi-
vidual bunches, be marked in some way to indicate to retailers and
consumers that the contents be kept at a Ioav temperature in order
that the edible quality may be retained.
THE ASPARAGUS CANNING INDUSTRY
II. Hickmott built the first large asparagus cannery in the United
States on Bouldin Island, in the Delta of California, three miles
southwest of Isleton, in 1892.
In 1899, The Golden State Asparagus Company was organized.
This company was established first on Grand Island opposite Walnut
Grove, but in 1904 moved to Isleton, where it is still operating. Since
1900, a number of asparagus canneries have been constructed along
the network of waterways of the Delta. By 1902, there were six
canneries in the Delta, chiefly for asparagus, and in 1924, twenty
canneries were packing asparagus.
The Asparagus Canning Regions of California. — The Sacramento
and San Joaquin valleys are the only regions of the state in which
asparagus is grown for canning. The soil of the Delta, particularly,
is well adapted to the growing of canning asparagus, most of it being
peat or muck, mixed with a small amount of sediment. This sediment
was formerly deposited over the land by the overflowing rivers. The
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 85
soil is so light and porous that the spears will grow through 15 to 18
inches of it and remain perfectly straight.
Cutting Season. — In California, the canning season usually starts
about April 1. The fields are usually cut until late in June, making
the cutting season for white asparagus from 12 to 14 weeks.
Preparatory Tillage. — After the green asparagus season is over,
the low ridges are disked down to destroy the weeds and loosen the
soil. Somewhat higher ridges, usually 14 to 18 inches above the
crowns, are then made by the use of 18 or 20-inch disks. As a rule,
the field must be gone over several times to get a sufficiently high
ridge. As the crowns become older, they grow toward the surface
and spread laterally, making necessary the use of more soil each year.
A light harrow, chain, or wooden float is often attached to the rear
of the disk to break the clods and give a smooth surface to the ridge.
The space between the ridges is also disked and harrowed thoroughly,
as it often becomes badly packed by the cutters during the green
asparagus season.
Cutting. — During harvesting for the cannery, the entire field is
cut each day. All the spears that have the tips through the ground
or that are breaking the ground are cut, to a length of approximately
9 inches, with a chisel-shaped knife.
The cutters start at daylight and work until the fields have been
gone over. As a rule, it is possible to can each day's harvest on the
same day it is cut. The cutters lay the asparagus on top of the ridges.
The spears from six to eight rows are laid on the two center ridges.
Usually only one row is cut at a time, as fewer of the spears are missed
than if an attempt is made to harvest the spears from two rows. If
a spear is missed, it will be green by the following day and will
therefore be placed in the green pack. Moreover, it has been found
by pedometer tests that more than twice as many steps are taken
when cutting two rows as when cutting one row at a time.
White asparagus is usually gathered and hauled from the field in
the same manner as green asparagus. From the fields it is carted
or sleded directly to the washing sheds, which are located along the
edges of the fields.
Trimming. — The asparagus is taken from the carts or sleds and
placed in wooden forms so that all the tips touch the back. When the
form has been filled, the spears are held firm by pressure from a*
board clamped on top. They are then trimmed to a uniform length
of about 7 inches by cutting off the butts with a long knife. A large
knife made from a cross-cut saw is generally used. The teeth are filed
86 UNIVERSITY OF CALIFORNLi EXPERIMENT STATION
off and the edge is usually made undulating before it is sharpened.
A few growers are now using machines for both trimming and wash-
ing. When a machine is finally perfected these operations will be
greatly facilitated, at least on the larger ranches.
Washing. — After trimming, the loose dirt is washed off with a
stream of water from a hose. The asparagus is then taken out of the
form, immersed in a trough of water and washed by rubbing the
spears together. A piece of rope about one foot long with a loop on
each end is usually slipped over the thumbs. This makes it possible
for the worker to handle much larger amounts at a time. It requires
skill to clean the spears properly during the washing operation.
Prompt washing after harvesting removes the adhering soil so that
it will not stain the white spears. In addition, it cools the spears and
retards deterioration. When washed, the spears are placed in lug
boxes and the covers nailed on.
Hauling to the Cannery. — The lugs of asparagus are collected
from the washing sheds several times each day by motor trucks, and
are hauled directly to the cannery or to a shipping point. Practically
all of the canneries are located on the waterfront. This makes it
possible to haul the fresh and the canned products by boat.
Grading. — The asparagus is taken from the lug boxes and placed
on the tables in front of the sorters. At the cannery, experienced
sorters, usually women, grade the asparagus. The number of grades
packed varies somewhat among the different canning companies. The
white and green spears are canned in practically every size (fig. 35).
At the present time the demand for the white exceeds that for the
green. The green asparagus referred to in canning has only a small
amount of green when compared with that shipped fresh. This is
usually sold as "green tips." If the spears have loose heads, that is,
are badly "flowered," or are very green, they are cut into short
lengths for soup stock. A small amount of peeled spears are also
canned. Usually only the very large spears are peeled.
As the various grades are sorted out, they are placed in small
wooden boxes holding about three pounds. When the boxes are filled,
they are carried on an endless conveyor to the trimmers.
Filling the Cans. — After the spears have been trimmed, they are
dumped into large wicker baskets. These are then immersed in vats
of water at or near the boiling point. This immersion in hot water
gives the spears a final washing, shrinks them, and makes them more
pliable. When brought to the cannery, the spears are fresh and
brittle ; immersion in hot water makes it possible to handle them
without danger of breaking. The baskets are next immersed in cold
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
87
water, or the spears sprayed with cold water. The asparagus is then
placed in enamel-lined sinks filled with water. A final sorting for
color and size, and an inspection for blemishes and cleanliness are
made.
The cans of asparagus are filled by hand. They are then conveyed
to the "briner" and filled with a hot salt solution. From the briner
they pass through an exhaust box, where the air is drawn from the
tissues and the liquid. The cans are then capped by an automatic
sealer.
Fig. 35. — Grades of asparagus for canning: 1, Giant; 2, Colossal; 3, Mam-
moth; 4, Large; 5, Medium; 6, Small; 7, Tiny. There are both "shorts" and
"longs" of these seven grades.
Square containers are generally used for asparagus. The vacuum
produced within the square can, after cooling, draws in the four sides
and holds the spears so that they cannot move about and rub off
the side leaves and buds. In the round can, where only the ends are
drawn in, there is more freedom of movement of the spears.
Processing. — After being sealed, the cans are collected in iron
trays, loaded on trucks, and rolled into the retorts, which are equipped
with recording thermometers. Care is used to obtain the proper heat-
ing. After processing the cans are stacked in a cool, well-ventilated
room before being placed in the warehouse. In the warehouse the
cans are tested for soundness and are labelled and boxed. Canned
88 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
asparagus seldom moves from the warehouse for several weeks after
canning. After standing for a time, the spears within a can become
uniform in color and become more homogeneous and attractive.
Quality. — Nearly all of the asparagus is canned the same day that
it is cut. The canneries begin to operate about the middle of the fore-
noon, continuing until that day's harvest has been canned. The great
rapidity of deterioration under ordinary storage conditions makes it
necessary to pack soon after harvesting. Bitting (2) found that aspara-
gus packed 3 or 4 hours after cutting had only a very small amount of
fibrous material at the butts of the spears, If allowed to stand 24 hours
before packing a marked increase in the amount of fiber in the "peel"
and at the butt is apparent. If there is a holdover from the previous
day's cutting, it is the custom among the canners to use only the tips
of the spears.
If it is impossible to pack the same day the spears are cut, they
should be stored where it is cool and moist. At ordinary temperatures
there is considerable heating of asparagus in lug boxes. This heating
hastens deterioration.
Asparagus Pack of California and Other States. — Except for a
few years, there has been a steady increase in the California asparagus
pack since the industry was started about 1890. This increase will
probably continue for some time to come because of the exploitation
of foreign markets. Canned asparagus has also been looked upon as
a luxury by most people. It is rightly the aim of the canners to make
it accessible to a greater portion of the population by taking it out of
the luxury class.
Exports of Canned Asparagus.- — Before the development of the
industry in California nearly all of the canned asparagus used in the
United States was imported from France. At present and for some
years past, California has been able to supply the entire domestic
demand and, besides, has shipped canned asparagus to almost every
country and province in the world. Export data obtainable from the
Bureau of Commerce Reports give the destination and the number of
pounds shipped.
In 1923, 8,766,431 pounds of canned asparagus were exported from
the United States, while in 1924, 9,919,680 pounds were exported.
The imports of canned asparagus in 1922 and 1923 were 526 and
6,787 pounds, respectively.
BUL. 446] THE ASPARAGUS INDUSTRY IN CALIFORNIA 89
FUNGOUS DISEASES
Asparagus Rust (Puccinia asparagi D.C.). — Asparagus rust was
first discovered in America in 1896. The same year the disease was
reported on Long Island, in Massachusetts, and in Connecticut.
Probably the rust had been introduced several years before that time
and had spread to a considerable extent before being observed. The
disease spread rapidly throughout the entire country, and within a
few years had reached the Pacific Coast. In California, the spread
of the rust was from south to north. It was first reported in southern
California and in the Milpitas district near San Jose in 1901 ; on
Bouldin Island and the surrounding territory as far up the Sacra-
mento Valley as Grand Island, in 1902, and about Vorden and the
city of Sacramento, in 1903.
Injury to the Host. — The organism does not injure the young
shoots that are cut for the market or for canning purposes. It makes
its first appearance in the producing fields on the asparagus stalks
after the cutting season is over. As is well known, the synthesis of
plant foods takes place in the green tissue of the asparagus plant, and
these foods are translocated to the fleshy roots and rhizome and there
stored in large quantity. Pood that is stored in the crown after the
commercial crop has been harvested furnishes energy for the growth
of the crop the following season. If the aerial shoots are injured
and the tissue used for synthesis of food is reduced in amount or in
effectiveness, less reserve material will be stored in the crowns. The
succeeding crop will be reduced in proportion as the reserve food
supply is diminished. The injury caused by the rust organism is due
mainly to destruction of the tissues that carry on the process of
food synthesis. When the rust organism attacks a plant, little or no
injury is appareunt until the spore clusters rupture the epidermis.
The ruptured areas become dry and take on a brownish color. When
the attack is severe, the entire plant or the entire field becomes brown
and dead in appearance.
Life History. — In asparagus rust there are four spore forms, as
follows: (1) teleutospores, (2) sporidia, (3) aecidiospores, and (4)
uredospores. All of these occur on the asparagus plant. They arise
from a mycelium which penetrates the tissues of the host. The rust
winters over in the soil or on the old asparagus plants in the resting
or teleutospore stage. These resting spores are two-celled (fig. 36).
They germinate in the spring of the year at about the same time that
90
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Fig. 36. — A cluster of teleutospores (winter spores) breaking
through the epidermis. (From Bui. 165.)
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
91
the asparagus plant starts to grow. From each cell of these thick-
walled spores there normally arises a short segmented filament or
promycelium bearing four small sporidia. These sporidia are carried
by wind, water or other means into contact with young shoots. Here,
in the presence of moisture, they germinate upon the surface of the
plant, and the mycelium grows through the epidermis and establishes
itself in the underlying tissue. This mycelium, after a growing period
Fig. 37. — Left, three separate germinating uredospores. The other figure
shows a uredospore germinating on the surface of the plant and entering the
stoma. (From Bull. 165.)
of less than a month, varying with climatic conditions, starts to
produce spores. These spores appear grouped under the epidermis,
each aggregation being known as a cluster cup or aecidium. The
aecidia appear in rather long, light green areas. The aecidiospores
are one-celled and orange colored. The developing spores of the
aecidium finally rupture the epidermis and are liberated. The aecidio-
spores are produced in series or chains. The outside cells of the chains
become rounded, are cut off, and are finally set free.
92
UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION
The aecidiospores are carried mainly by the wind and may fall
upon the stems and cladophylls of the same or other asparagus plants.
In the presence of moisture, these spores germinate and produce a
mycelium that grows through the stomata opening into the chloro-
phyll-bearing tissue below (figs. 37 and 38). The fungal threads are
localized mainly in the chlorophyll-bearing tissue, and in their growth
force the cells of the host apart. Food is absorbed from the cells of
Fig. 38. — Uredospore germinating on the surface of the plant, and penetrating
the stoma. Portion of asparagus stem shown in cross-section. (From Bui. 165.)
the host plant, for the nourishment of the parasite, by the special
absorptive organs known as haustoria. This mycelium produces the
summer rust, red rust, or uredospore stage, which is the one in which
the greatest amount of damage is done. The first signs of the summer
rust appears two or three weeks after infection by the aecidiospores.
The clusters of developing, single-celled uredospores rupture the
epidermis (fig. 39), and the spores are carried by air currents, gravity
or other means to reinfect other plants or different portions of the
same plant. At this stage, especially in regions of excessive summer
rainfall or where summer dews are prevalent, the spread of the rust is
very rapid. Under favorable conditions of temperature and moisture,
the life cycle from uredospore to uredospore is reported as often being
less than twelve days. These spores are the chief means of distribut-
Bul. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
93
ing the disease during the growing season. According to Smith the
uredospores when dry retain their viability for a period of three or
four months.
Fig. 39. — A cluster of uredospores (summer spores) breaking through the
epidermis of the host. Note the fungus threads in the tissue of the host.
(From Bul. 165.)
Accompanying the uredospore stage and sometimes occurring
alone, is the teleutospore stage, also known as the fall or winter rust
stage. The teleutospores appear in greatest abundance in the late
summer and early fall and arise from the same mycelium as the
uredospores. Most of the teleutospores adhere to the plant and prob-
94 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
ably provide the only means of carrying the disease over winter. They
remain dormant until temperature and moisture conditions are favor-
able for their development the following spring. The teleutospores
probably lose their viability after about one year. Smith (21) (Cali-
fornia) collected teleutospores from the previous year's crop on
June 27 and in a number of tests was able to get only one spore to
germinate. Either the spores had lost their viability or they had
germinated previously.
Environmental Relations. — The prevalence of asparagus rust is
closely related to environmental conditions. Moisture is necessary for
the germination of the spores. In the east, where dews are prevalent
throughout the entire growing season, the spread of the rust from plant
to plant and from field to field is very rapid. In the dry, semi-arid
regions of the west, the asparagus rust does not spread so rapidly.
Smith (22) states "that the amount of rust varies directly and exactly
with the amount of dew, and that so long as there is little or no dew
there can be no rust." The Imperial Valley of California is notably
free from dew and also free from asparagus rust. In the San Fer-
nando Valley, where dews are frequent, the rust does considerable
damage. Also, in that part of the Santa Clara Valley adjacent to the
lower end of San Francisco Bay, summer dews are prevalent, and the
asparagus fields are subject to severe epidemics of rust. This region
is now a much less important asparagus producing center than it was
two decades ago. In the Delta there is very little or no summer rain,
dew, or fog, and rust is of minor importance during most years,
except on the young beds which are harvested for only a short time.
The prevailing winds on the California coast are from the west, but
in the great interior valley the general direction of the winds is
changed to "up valley." A strong westerly breeze usually blows
inland through the Straits of Carquinez, which is the outlet of both
valleys. The "summer trade winds" set in regularly some time in
May and continue with but an occasional interruption by a " norther ' '
until October. This strong westerly wind blows over the Delta
throughout the summer and prevents the deposition of dew except
behind windbreaks or in other wind protected situations. It is in these
sheltered places that rust usually makes its first appearance.
Resistant Varieties, — Martha Washington is claimed to be the most
highly rust-resistant variety of asparagus grown in America today.
While Mary Washington may be slightly less resistant to rust attack
than the Martha Washington, it does not suffer appreciably from rust
attack. Mary Washington seems to be somewhat more susceptible,. to
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 95
attack of rust in California than in the eastern states. These two
varieties, however, have almost replaced all other varieties where rust
is prevalent. Mary Washington is becoming very popular in nearly
all of the important asparagus growing regions, not only because of its
rust resistance but because of its earliness, large size, and tendency
for the growing spears to hold a tight head longer than other varieties.
Spraying and Dusting. — In the eastern states much experimental
work was done to determine the best methods of dusting and spraying
but the results were never entirely satisfactory. Smith, VZI> working
in California, found that dusting with sulfur gave satisfactory control.
When rust appears early, one application of 25 to 30 pounds to the
acre about three weeks after the cutting season, and another about a
month later, should usually be sufficient. On newly planted beds or
when cutting stops early in the season, more than two applications
may be necessary. However, it is impossible to give specific directions
that will cover all conditions. Finely divided sulfur gives the best
results. The plants should be thoroughly covered with dust.
If the acreage is small, the sulfur can be applied with a hand
duster; in large fields, however, a power duster should be used that
will cover several rows at a time.
Other Methods of Control. — Burning the stalks of infested fields
in the fall will kill many of the spores. This does not add greatly to
the preventive methods, however, as the "needles" which have become
infected fall off after severe frosts and usually before the tops are
cut and burned. Volunteer plants about the edges of the fields, in
fence rows, and on the levees and ditch banks, should be grubbed out
so that they will not harbor the disease.
The fields should be planted so that they will secure good aeration ;
the rows should run in the direction of the prevailing winds. It is
usually inadvisable to plant windbreaks about the asparagus fields.
In regions, such as the Delta, where rust usually does not appear on
the older beds until fall, the best and cheapest method of rust control
is to secure good field aeration.
Violet Root Rot (Rhizoctonia crocorum var. asparagi (Pers.)
D.C.). — In parts of Europe the losses from violet root rot of asparagus
have been widespread and sometimes severe. The disease has been
reported in the United States, but has occasioned no losses worthy of
note.
In the asparagus bed, violet root rot is usually first noticed attack-
ing only a few plants, but every year, unless the disease is checked,
new surrounding plants are infected and die. On newly infected
96 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
plants, the mycelium shows itself on the roots as a violet-colored mass
of filaments. In badly infected plants, the soft tissue of the roots is
largely destroyed, and they have the appearance of hollow, withered
tubes, sometimes covered with characteristic small violet or dark tufts.
INSECTS AND OTHER PESTS
The asparagus plant, both in Europe and America, is host to a
number of very destructive insect pests.
The Common Asparagus Beetle (Crioceris asparagi L.). — The
common asparagus beetle is found in almost all of the asparagus
growing regions of Europe and America. In the United States the
damage caused by it appears to be less in the southern than in the
northern states. So far as known, it has not been reported as occur-
ring in the Imperial Valley of California.
Description. — The adult beetle is a slender and graceful insect,
slightly less than one-fourth inch long. It is blue-black in color with
red thorax and dark blue wing covers, marked with lemon yellow and
with reddish borders. The markings of the wing covers are quite
variable, the pale color sometimes forming submarginal spots, while
in other specimens it becomes so diffused as to form the principal color
of the wing covers. Like a squirrel, it commonly hides on the opposite
side of the branch when approached. The egg is dark brown and
oval, is nearly one-sixteenth of an inch long, and is laid on end. The
eggs are deposited upon the stems or foliage, usually two to seven or
more in a row. The mature larva is about one-third of an inch long,
soft and fleshy, much wrinkled, and of a dark gray or olive color, with
shining black head and legs. The mature larva drops to the ground
from the asparagus plant, and just beneath the soil surface forms a
small, rounded, thin, earth-covered cocoon (fig. 40), within which it
changes to the pupa, The latter is yellowish in color.
Life History. — The insect winters over in the adult stage, hiber-
nating in rubbish and other protected places. In the latitude of the
District of Columbia (Chittenden), the beetles usually appear in
April, but as a rule in most districts they appear about the same time
as the asparagus in the spring. The beetles soon start to lay eggs.
These hatch in from three to eight days, depending on the tempera-
ture. The larvae soon become full grown in from ten to fourteen
days, and then pupate in the soil. The adult beetle emerges in about
a week. The insect may pass through its entire life cycle in as short a
time as three weeks, though it may take a month or more. In its
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA
97
Fig. 40. — Cocoons of asparagus beetle. Observe the adult beetle.
98 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
northern range, usually two generations are produced in a season ;
farther south, as many as four broods may be produced. In California
(Essig (9) ) there are many overlapping generations each year.
Nature of Injury. — Both the larval and adult stages of the aspara-
gus beetle feed upon the marketable spears as well as upon the
foliage and stems of the mature stalks. During the cutting season the
adults do the greatest amount of damage by depositing their eggs
upon and eating holes in the spears, making them unsightly and
lowering their market value.
Control. — Asparagus beetles are held in check to a certain extent
by natural enemies. Several species of ladybird beetles feed upon the
eggs, while numerous soldier-bugs and small dragon flies prey upon
the larvae. According to Johnston (13) at times the beetle is kept under
control by a parasitic wasp-like fly, Tetrastichus asparagi Cwfd. The
parasite deposits its eggs on those of the asparagus beetle ; the beetle
egg hatches, the larva grows to maturity, enters the soil and forms a
pupal cell but does not pupate because the pupa is entirely consumed
by the parasite. The parasites pupate and later come forth as adults
from the cell which the beetle larva has constructed.
In the Concord, Massachusetts, district Chittenden (6) has observed
that large numbers of hibernating beetles are killed during the winter,
especially when extremely low temperatures follow a period of warm
weather. During extremely high temperatures, exposed larvae, as
well as eggs, are destroyed. This injury by extremes of temperature
probably holds this pest in check in the far northern and the extreme
southern districts and probably accounts for its not being found in
the Imperial Valley.
Chickens and ducks feed upon both the adults and the larvae and
do not injure the plants; however, their use is limited to small areas.
Air-slacked lime dusted on the plants, when wet with dew, will kill
the larvae but not the adults.
In certain districts where the attacks are especially severe, the
spears are cut white; as soon as the tips appear, they are harvested
before the beetle has an opportunity to do any great amount of
damage. When cutting white asparagus, trap hills or trap rows of
asparagus can be used to good advantage. The beetles are forced to
congregate and feed on the rows or hills that are not being cut. These
should be thoroughly dusted or sprayed with an arsenical every week
or ten days. It will also be necessary to grub out the volunteer host
plants about the edges of the fields and ditches if good results are to
be expected.
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 99
Where green asparagus is being cut, trap crops are not so effective,
as the beetles can feed and lay their eggs upon the young spears before
they are harvested. The spears are cut, however, before the eggs
hatch. On the young beds, and after the cutting season on the older
ones, an excellent method of control is to spray with lead arsenate,
using 4 pounds of lead arsenate paste and 4 pounds of resin fishoil
soap to 50 gallons of water. A dust comprised of 1 part of powdered
arsenate and 8 to 10 parts of air-slaked lime applied while the plants
are wet with dew will also give excellent control. Young larvae are
effectively killed with 5 per cent nicodust.
A number of asparagus growers in the Delta report complete
extermination of hibernating beetles in fields that have been flooded
during the winter.
To obtain the best control, community action is necessary.
The Twelve-spotted Asparagus Beetle (Crioceris duodecimpunc-
tata L.) has not been reported as occurring in the western United
States and is probably confined to the eastern half.
Asparagus Miner (Agromyza simplex Loew.). — The asparagus
miner has a wide distribution and has been reported as occurring in
many sections of the country, including Florida, Texas, Washington,
and California. At times it becomes very abundant in the north.
Description. — According to Fink (14) the adult is a glistening
metallic black fly about one-sixth of an inch in length and with a wing
expanse of about one-fifth of an inch. The males are somewhat smaller
than the females, and have a more or less triangular shaped abdomen.
One of the striking features in the adult is a picture of a face on the
thorax. When first laid, the egg is glistening white in color. It
measures 0.5 millimeters in length and 0.12 millimeters in width. The
egg is elongate-oval, slightly widened at one end, and more or less
pointed at the other. The egg shell is at first viscid and transparent
so that the embryo is clearly visible through the shell. When first
hatched, the larva is pure white, but when fully grown is cream-Avhite.
When mature it is 4-5 millimeters long, about five times longer than
wide, of nearly uniform diameter throughout a greater portion of its
length, and narrowing slightly toward either end. When first formed,
the pupa is light brown ; later it becomes dark brown. It is flat and
curved when viewed from the side. A pair of hooks is borne at each
end of the pupa, by means of which it attaches itself firmly beneath
the epidermis of the asparagus stalk.
Life History. — Fink (10) reports that in the vicinity of Ithaca, New
York, the adults probably make their appearance about the middle of
100 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
May, the males appearing several days before the females. The female
starts to deposit eggs within a week after she emerges. Eggs are
usually laid at the base of the stalk, at or near the surface of the
ground or below the surface, if the soil is loose. The eggs are deposited
individually just below the epidermis. It is rather difficult to find
the eggs unless the female is found ovipositing. If a stalk on which
the oviposition has been observed is pulled out and examined carefully
with a hand lens, tiny punctures leading to raised areas will be^seen.
If the epidermis is carefully peeled from these raised areas, the egg
is found adhering either to the peeled epidermis or to the tissues of
the stalk below. It is more difficult for the female to penetrate old
stalks, and in case eggs are deposited on these part of the egg may
remain protruding from the epidermis.
The entire life cycle, except the adult stage, is passed in conceal-
ment beneath the epidermis of the asparagus stalk.
The eggs hatch in twelve to eighteen days. When hatched the
larvae begin to mine their way up the stalk for a foot or more above
the surface of the soil and then work downward again, thus producing
zigzag mines. Usually a number of larvae are found on the same
stalk. When nearly full-grown, the larvae direct their mines down-
ward. During the summer they may pupate anywhere along the
stalk; later they pupate at depths of one inch or more below the soil
surface. The pupae are found in the mines where larvae have stopped
feeding. During the summer, the insects remain in the pupal stage
two to three weeks. The fall brood, however, winters over in the
pupal stage.
In California, according to Essig, (9) the flies appear early in the
spring ; there are at least two generations a year.
Nature of Injury. — The injury to the asparagus stalks is done by
the larvae which mine at the base of the stalk under the epidermis.
Chittenden (6) reports finding pupae under the outer skin of the roots,
also. Cases have been reported in which entire beds have been
destroyed by the ravages of this insect. The adult does not lay eggs
on the young spears (Fink) during the cutting season, but by prefer-
ence oviposits on the stalks in the new beds and in the nursery.
Control. — Methods of control used at the present time are not
entirely satisfactroy. Fink (10) recommends the addition of syrup as
an attractant to an arsenical spray, which is used to kill the adults.
He also recommends pulling and destroying the infested stalks in late
fall or early spring. These stalks generally turn yellow and in severe
cases die before the non-infested.
Btjl. 446]
THE ASPARAGUS INDUSTRY IN CALIFORNIA
101
The Asparagus Fly (Platyparea pocciloptera Schrank). — So far
no mention has been made of this pest in the United States.
The Garden Centipede (Scutigerella immacidata Newport). — The
garden centipede is found widely distributed throughout the world.
It is an economic pest in many of the important truck crop regions
of California, Oregon, and Utah. So far as known, it has not been
reported as a serious asparagus pest except in the Delta region of
California.
Fig. 41. — Asparagus or garden
centipede (adult). X 10.
Fig. 42. — Eggs of the garden
centipede (much enlarged).
Description. — The adult (fig. 41) is small and unusually white in
color, though its body is often tinged by colored food material in the
digestive tract. When feeding on young asparagus shoots, however,
they are almost transparent white. According to Wymore, (28) the
adults vary in length from 2.7 to 6.7 millimeters; they have one pair
of many-jointed antennae, an eye-like body just back of each antenna,
four pairs of mouth appendages; twelve pairs of well-developed legs,
the first pair four-jointed, all the rest five-jointed.
Life History. — According to Wymore, (28) "When first laid the
eggs are a pearly white and as the time for hatching approaches they
become a dirty white color (fig. 42). They are % to % millimeter in
diameter and are covered with tiny ridges giving the appearance of a
net work.
"When just hatched the larvae are hairy, vary from 0.9 to 1.1
millimeters in length, and have six pairs of legs." The first molt
occurs three to five days after hatching.
102 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
Fig. 43. — Injury to asparagus due to garden centipede.
BuL. 446] TPIE ASPARAGUS INDUSTRY IN CALIFORNIA 103
The life history has not been worked out in detail. Wymore was
able to find adult specimens in the soil about the asparagus crowns at
almost any time of the year. During the first part of June, the young
greatly outnumber the adults, but by the middle of August, 90 per
cent of the individuals taken in the field were mature.
The centipedes feed beneath the surface of the soil, eating small
holes in the spears and making them unfit for canning.
Control. — Wymore (28) recommends flooding for a period of two
weeks where the ground is kept covered to a depth of a foot or more
and all asparagus tops, stubble, and other debris are entirely sub-
merged. He states that where the soil, but not the stubble, was covered
with four or five inches of water, very good results were obtained by
stirring up the muddy soil with a potato hook, thus disturbing the
centipedes and allowing water to reach them more quickly. If this
was not done, it seemed impossible to drown the pests, although the
soil was kept covered for three or four weeks with several inches of
water. Evidently in this case, the insects found lodgment in and
about the stems and received sufficient oxygen which was conveyed
down the stems that projected above the water surface. Flooding as
a means of control cannot be used in many of the asparagus districts
outside of the Delta, except where a large supply of water is available.
To date, satisfactory control methods by use of repellants and soil-
fumigants have not been developed.
Other Pests. — Other insects reported by Essig as feeding on
asparagus in California are : the Harlequin Cabbage Bug {Murgentia
histrionica Hahn.), Orange Tortrix (Tortrix citrana Fernald), and
the Yellow Bear Caterpillar (Diacrisea virginica Fab.). Wymore
observed that the tops of several acres of asparagus in the Delta in
the late autumn of 1922 turned white from the injury of pentotomids
(chiefly Chlorochrou sayi Stal. and Thyanta eitstator Fab.). The bugs
were found in large clusters on the stems about 18 inches from the
tips of the branches, where they were girdled by the many punctures
from the mouth parts.
The authors have observed red spider and thrips in considerable
abundance on the asparagus plants, especially during late summer.
Thrips injury has been found to be very serious in nursery beds in
the San Fernando Valley. In early spring Aphis sp. are often found
on the spears and on the young seedlings in the nursery. Gophers
feed upon both the fleshy roots and stalks and do considerable damage
if not trapped.
104 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION
LITERATURE CITED
i Bisson, C. S., H. A. Jones, and W. W. Bobbins.
1926. Factors influencing the quality of fresh asparagus after it is har-
vested. California Agr. Exp. Sta. Bui. 410:1-28.
2 Bitting, K. G.
1917. Deterioration in asparagus. Nat. Canners Assoc. Bui. 11:1-18.
s Borthwick, H. A.
1925. Factors influencing the rate of germination of the seed of Asparagus
officinalis. California Agr. Exp. Sta. Tech. Paper 18:1-17.
* Bottner, J.
1921. Praktischer Lehrbuch des Spargelbaues 122: p. 74, figs. 1-74.
Trovitsch, Frankfurt.
5 Brooks, W. P., and F. W. Morse.
1919. A fertilizer experiment with asparagus. Massachusetts Agr. Exp.
Sta, Bui. 194:231-257.
6 Chittenden, F. H.
1917. The asparagus beetles and their control. U. S. Dept, Agr. Farmers'
Bui. 837:1-13.
< Close, C. P.
1903. Report of the horticulturist. I. Nitrate of soda on asparagus.
Delaware Agr. Exp. Sta. Ann. Kept. 14:89-90.
s Close, C. P., T. H. White, and W. R. Ballard.
1911. Fertilizers on asparagus. Maryland Agr. Exp. Sta. Bui. 151:135-
146.
9 Essig, E. O.
1915. Injurious and beneficial insects of California, (Ed. 2.) Monthly
Bui. California State Comm. Hort. Supplement, pp. 1-541.
io Fink, D. E.
1913. The asparagus miner and the twelve-spotted asparagus beetle.
Cornell Agr. Exp. Sta, Bui. 331:411-435.
ii Greene, W. J.
1891. Asparagus. Ohio Agr. Exp. Sta, Bui. 24 (2nd ser. 2):241-244.
12 Ilott, Chas.
1901. The book of asparagus. 108 pp. John Lane, London and New York,
is Johnston, Frederick Andrew
1915. Asparagus-beetle egg parasite. Jour. Agr. Res. 4:303-314.
i^Loisel, M.
1924 L'Asperge, culture naturelle et artificielle. Librairie Agricole de la
Maison Rustique. (10th ed.) 136 pp. F. Lesourd, Paris,
is Meyer, E. H.
1913. Spargelbau und Konservegemiise nach Braunschweiger Methode.
(ed. 2.) 63 pp. Paul Parey, Berlin,
ic Morse, Fred W.
1913. Some effects of fertilizers on the growth and composition of
asparagus roots. Massachusetts Agr. Exp. Sta. Ann. Rept. 25:156.
BUL. 446] T HE ASPARAGUS INDUSTRY IN CALIFORNIA 105
17 Myers, C. E.
1916. Experiments with asparagus. Pennsylvania State College Ann. Rept.,
pp. 557-578.
is Norton, J. B.
1919. Washington asparagus: information and suggestions for growers of
new pedigreed rust-resistant strains. U. S. Dept. Agr. Off.
Cotton, Truck and Forage Diseases Circ. 7:1-8.
is Rousseaux, E., and C. Brioux. x
1906. Recherches sur la culture de l'Asperge dans l'Auxerrois. (Memoirs
Societe d 'encouragement pour l'industrie nationale) 112 pp.
Siege de la Societe, Paris.
20 Rudolfs, W.
1921. Experiments with common rock salt. I. Effect on asparagus. Soil
Sci. 12:449-456.
2i Smith, R. E.
1905. Asparagus and asparagus rust in California. California Agr. Exp.
Sta. Bui. 165:1-99.
22 Smith, R. E.
1904. Report on asparagus rust investigations. California Agr. Exp. Sta.
Circ. 9:1-20.
23 Tiedjens, Victor A.
1924. Some physiological aspects of Asparagus officinalis. Proc. Amer.
Soc. Hort. Sci. 21:129-140.
24 Walker, E.
1905. Asparagus and salt. Arkansas Agr. Exp. Sta. Bui. 86:31-36.
25 Warren, G. F., and Jennie A. Voorhees.
1907. JSTew Jersey Agr. Exp. Sta. Ann. Rept. 27:189-223.
26 Working, E. B.
1922. Physical and chemical factors in the growth of asparagus. Carnegie
Inst. Wash. Year Book 21:63-64.
27 Working, E. B.
1924. Physical and chemical factors in the growth of asparagus. Arizona
Agr. Exp. Sta. Tech. Bui. 5:85-124.
28 Wymore, F. H.
1924. The garden centipede, Scutigerella immaculata (Newport), a pest
of economic importance in the West. Jour. Econ. Ent. 17:520-
526.
STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION
No.
253. Irrigation and Soil Conditions in the
Sierra Nevada Foothills, California.
262. Citrus Diseases of Florida and Cuba
Compared with those of California.
263. Size Grades for Ripe Olives.
268. Growing and Grafting Olive Seedlings.
273. Preliminary Report on Kearney Vine-
yard Experimental Drain, Fresno
County, California.
276. The Pomegranate.
277. Sudan Grass.
278. Grain Sorghums.
279. Irrigation of Rice in California.
283. The Olive Insects of California.
294. Bean Culture in California.
804. A Study of the Effects of Freezes on
Citrus in California.
310. Plum Pollination.
312. Mariout Barley.
813. Pruning Young Deciduous Fruit
Trees.
819. Caprifigs and Capriication.
324. Storage of Perishable Fruit at Freez
ing Temperatures.
825. Rice Irrigation Measurements and
Experiments in Sacramento Valley,
1914-1919.
328. Prune Growing in California.
331. Phylloxera-Resistant Stocks.
835. Cocoanut Meal as a Feed for Dairy
Cows and Other Livestock.
839. The Relative Cost of Making Logs
from Small and Large Timber.
840. Control of the Pocket Gopher in
California.
343. Cheese Pests and Their Control.
344. Cold Storage as an Aid to the Mar-
keting of Plums.
346. Almond Pollination.
347. The Control of Red Spiders in Decid
nous Orchards.
848. Pruning Young Olive Trees.
349. A Study of Sidedraft and Tractor
Hitches.
850. Agriculture in Cut-over Redwood
Lands.
853. Bovine Infectious Abortion.
354. Results of Rice Experiments in 1922.
857. A Self-mixing Dusting Machine for
Applying Dry Insecticides and
Fungicides.
858. Black Measles, Water -Berries, and
Related Vine Troubles.
361. Preliminary Yield Tables for Second
Growth Redwood.
362. Dust and the Tractor Engine.
863. The Pruning of Citrus Trees in Cali-
fornia.
864. Fungicidal Dusts for the Control of
Bunt.
365. Avocado Culture in California.
866. Turkish Tobacco Culture, Curing and
Marketing.
367. Methods of Harvesting and Irrigation
in Relation of Mouldy Walnuts.
368. Bacterial Decomposition of Olives dur-
ing Pickling.
369. Comparison of Woods for Butter
Boxes.
370. Browning of Yellow Newtown Apples.
371. The Relative Cost of Yarding Small
and Large Timber.
373. Pear Pollination.
374. A Survey of Orchard Practices in the
Citrus Industry of Southern Cali-
fornia.
375. Results of Rice Experiments at Cor-
tena, 1923.
376. Sun-Drying and Dehydration of Wal
nuts.
377. The Cold Storage of Pears.
379. Walnut Culture in California.
BULLETINS
No.
380.
382.
385.
386.
387.
389.
390.
391.
392.
393.
395.
396.
397.
399.
400.
401.
402.
404.
405.
406.
407.
408.
409.
410.
411.
412.
414.
415.
416.
417.
418.
419.
420.
421.
422.
423.
424.
425.
426.
427.
428.
429.
Growth of Eucalyptus in California
Plantations.
Pumping for Drainage in the San
Joaquin Valley, California.
Pollination of the Sweet Cherry.
Pruning Bearing Deciduous Fruit
Trees.
Fig Smut.
The Principles and Practice of Sun-
drying Fruit.
Berseem or Egyptian Clover.
Harvesting and Packing Grapes in
California.
Machines for Coating Seed Wheat with
Copper Carbonate Dust.
Fruit Juice Concentrates.
Crop Sequences at Davis.
Cereal Hay Production in California.
Feeding Trials with Cereal Hay.
Bark Diseases of Citrus Trees.
The Mat Bean (Phaseolus aconitifo
lius).
Manufacture of Roquefort Type Cheese
from Goat's Milk.
Orchard Heating in California.
The Blackberry Mite, the Cause of
Redberry Disease of the Himalaya
Blackberry, and its Control.
The Utilization of Surplus Plums.
Cost of Work Horses on California
Farms.
The Codling Moth in Walnuts.
The Dehydration of Prunes.
Citrus Culture in Central California.
Stationary Spray Plants in California.
Yield, Stand and Volume Tables for
White Fir in the California Pine
Region.
Alternaria Rot of Lemons.
The Digestibility of Certain Fruit By-
products as Determined for Rumi-
nants.
Factors Affecting the Quality of Fresh
Asparagus after it is Harvested.
Paradichlorobenzeno as a Soil Fumi-
gant.
A Study of the Relative Values of Cer-
tain Root Crops and Salmon Oil as
Sources of Vitamin A for Poultry.
Planting and Thinning Distances for
Deciduous Fruit Trees.
The Tractor on California Farms.
Culture of the Oriental Persimmon
in California.
Poultry Feeding: Principles and
Practice.
A Study of Various Rations for
Finishing Range Calves as Baby
Beeves.
Economic Aspects of the Cantaloupe
Industry.
Rice and Rice By-products as Feeds
for Fattening Swine.
Beef Cattle Feeding Trials, 1921-24.
Cost of Producing Almonds in Cali-
fornia ; a Progress Report.
Apricots (Series on California Crops
and Prices) .
The Relation of Rate of Maturity to
Egg Production.
Apple Growing in California.
Apple Pollination Studies in Cali-
fornia.
The Value of Orange Pulp for Milk
Production.
The Relation of Maturity of Cali-
fornia Plums to Shipping and
Dessert Quality.
Economic Status of the Grape Industry.
CIRCULARS
No. No.
87. Alfalfa. 259.
117. The Selection and Cost of a Small 261.
Pumping Plant. 262.
127. House Fumigation. 263.
129. The Control of Citrus Insects. 264.
136. Melilotus indica as a Green-Manure
Crop for California. 265.
144. Oidium or Powdery Mildew of the 266.
Vine.
157. Control of the Pear Scab. 267.
164. Small Fruit Culture in California.
166. The County Farm Bureau. 269.
170. Fertilizing California Soils for the 270.
1918 Crop. 272.
173. The Construction of the Wood-Hoop
Silo. 273.
178. The Packing of Apples in California. 276.
179. Factors of Importance in Producing 277.
Milk of Low Bacterial Count.
202. County Organizations for Rural Fire 278.
Control.
203. Peat as a Manure Substitute. 279.
209. The Function of the Farm Bureau.
212. Salvaging Rain-Damaged Prunes. 281.
215. Feeding Dairy Cows in California.
217. Methods for Marketing Vegetables in
California. 282.
230. Testing Milk, Cream, and Skim Milk
for Butterfat. 283.
231. The Home Vineyard. 284.
232. Harvesting and Handling California 285.
Cherries for Eastern Shipment. 286.
234. Winter Injury to Young Walnut Trees 287.
during 1921-22. 288.
238. The Apricot in California. 289.
239. Harvesting and Handling Apricots 290.
and Plums for Eastern Shipment. 291.
240. Harvesting and Handling Pears for
Eastern Shipment. 292.
241. Harvesting and Handling Peaches for 293.
Eastern Shipment. 294.
243. Marmalade Juice and Jelly Juice from 295.
Citrus Fruits.
244. Central Wire Bracing for Fruit Trees. 296.
245. Vine Pruning Systems.
248. Some Common Errors in Vine Prun- 298.
kig and Their Remedies.
249. Replacing Missing Vines. 300.
250. Measurement of Irrigation Water on 301.
the Farm. 302.
252. Supports for Vines. 303.
253. Vineyard Plans.
254. The Use of Artificial Light to Increase 304.
Winter Egg Production. 305.
255. Leguminous Plants as Organic Fertil- 306.
izer in California Agriculture.
256. The Control of Wild Morning Glory. 307.
257. The Small-Seeded Horse Bean. 308.
258. Thinning Deciduous Fruits. 309.
Pear By-products.
Sewing Grain Sacks.
Cabbage Growing in California.
Tomato Production in California.
Preliminary Essentials to Bovine
Tuberculosis Control.
Plant Disease and Pest Control.
Analyzing the Citrus Orchard by
Means of Simple Tree Records.
The Tendency of Tractors to Rise in
Front; Causes and Remedies.
An Orchard Brush Burner.
A Farm Septic Tank.
California Farm Tenancy and Methods
of Leasing.
Saving the Gophered Citrus Tree.
Home Canning.
Head, Cane, and Cordon Pruning of
Vines.
Olive Pickling in Mediterranean Coun-
tries.
The Preparation and Refining of Olive
Oil in Southern Europe.
The Results of a Survey to Determine
the Cost of Producing Beef in Cali-
fornia.
Prevention of Insect Attack on Stored
Grain.
Fertilizing Citrus Trees in California.
The Almond in California.
Sweet Potato Production in California.
Milk Houses for California Dairies.
Potato Production in California.
Phylloxera Resistant Vineyards.
Oak Fungus in Orchard Trees.
The Tangier Pea.
Blackhead and Other Causes of Loss
of Turkeys in California.
Alkali Soils.
The Basis of Grape Standardization.
Propagation of Deciduous Fruits.
The Growing and Handling of Head
Lettuce in California.
Control of the California Ground
Squirrel.
The Possibilities and Limitations of
Cooperative Marketing.
Coccidiosis of Chickens.
Buckeye Poisoning of the Honey Bee.
The Sugar Beet in California.
A Promising Remedy for Black Measles
of the Vine.
Drainage on the Farm.
Liming the Soil.
A General Purpose Soil Auger and its
Use on the Farm.
American Foulbrood and its Control.
Cantaloupe Production in California.
Fruit Tree and Orchard Judging.
The publications listed above may be had by addressing
College of Agriculture,
University of California,
Berkeley, California.
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