CALIFORNIA AGRICULTURAL EXTENSION SERVICE CIRCULAR 92 July, 1935 SPINACH PRODUCTION IN CALIFORNIA G. W. SCOTT Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA Digitized by the Internet Archive in 2011 with funding from University of California, Davis Libraries http://www.archive.org/details/spinachproductio92scot SPINACH PRODUCTION IN CALIFORNIA a. W. SCOTT ^ Spinach is the most important crop grown for greens in this country. It has been found to be valuable for so many different reasons, in a nutritive sense, that it has become the symbol of good diet. When raw it contains unusual quantities of vitamins A, B, and C ; and even when cooked or canned it is an outstanding vegetable source of these vitamins. It is rich in minerals, particularly iron, calcium, and phosphorus; and it serves as an excellent blood-forming food. Since its caloric content is low, it may be added to a practically full menu without danger of in- creasing the consumer's weight. Studies on the effect of cooking on vitamin and soluble-mineral con- tent have shown the least loss to occur when spinach is steamed, or cooked with practically no added water. During the commercial canning process vitamins A, C, and G are little affected, although B may be de- stroyed to a considerable extent. On the whole, spinach in any form must be considered one of the richest sources of vitamins A and C, a good vegetable source of B and G, a good source of calcium and of phos- phorus, and an excellent source of iron. The improved quality of the canned product and the publicity given this form of the vegetable have also been important factors in its increased consumption. In the larger city markets fresh spinach is now available in large quantities from early fall until late spring and in smaller quantities throughout the summer. During the cool seasons the fresh vegetable can be made available in the home garden with a small amount of effort. During the warmer season, when true spinach does not thrive, its place in the home garden may be taken by the New Zealand type of spinach (see page 25). A high-quality canned product is, of course, available throughout the year. PRODUCTION AREAS IN THE UNITED STATES The production of spinach can be divided into two classes : that for market and that for manufacture or canning. Spinach for market is grown to some extent in nearly all sections of the United States. Most of the carlot shipments, however, originate in Texas. A section along the Atlantic Coast, consisting of the Norfolk sec- Research Assistant in the Experiment Station. [3] 4 California Agricultural Extension Service [Cm. 92 tion of Virginia and the eastern shore of Maryland is next in importance. Carlot shipments (fig. 1) from California constitute a very small part of the total movement of this crop ; and within the state they comprise only a small part of the total spinach grown for market. The greater part of the California market crop is hauled to the larger markets of the //.ooo /o,ooo 9.000 8,000 ZOOO ^ 6.000 \ ^ s.ooo h 4.000 s.ooo e.ooo /,ooo / ^ p a 1 1 1 1 ■A / f U II 1 1' 1 H 1 1 1 1 1 1 \ 1 1 1 1 I 1 r ii 1 ^-1 1 ii 7- f rr / 1 3 \ I •; 1 L — 1 1 1 ^ '^6 'B7 '23 '£9 'SO '3/ '32 '33 H Ca//for/?/<7 ^^^tra/n/a,Jl^ary/anJ^^^/l// Mers Fig, 1. — Carlot shipments of market spinach in the United States for the yean 1924 to 1933. state by motor truck. Table 1 shows the receipts by months, of spinach, expressed in carlot equivalents, on the Los Angeles market for the years 1929 to 1933, inclusive, and on the San Francisco market for the years 1931 to 1933, inclusive. Evidently the out-of-state shipments represent less than one-tenth of the total crop produced for market in this state. California is the chief producer of canned spinach. Maryland ranks second in importance, with smaller production in New York, Texas, and a few other states. In 1933 California canned approximately 62 per cent and in 1934 approximately 74 per cent of the total spinach pack of the country. Spinach Production in California 5 PRODUCTION AREAS IN CALIFORNIA Spinach production for market in California is localized principally in the winter-vegetable sections of Imperial County, the counties sur- rounding the city of Los Angeles, the coast counties south of San Fran- cisco, and smaller acreages in Sacramento and San Joaquin counties. The principal loading points for carlot shipments are Imperial Valley points, Sacramento, Stockton, Los Angeles, Salinas, San Jose, Niles, TABLE 1 Carlot Equivalent Receipts of Spinach by Months on the Los Angeles AND San Francisco Wholesale Markets* Year Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. Total Los Angeles wholesale market 1929 127 130 172 109 78 76 66 61 69 93 74 100 1,155 1930 102 116 127 111 71 77 71 66 91 120 93 99 1.144 1931 115 123 116 97 117 104 69 45 73 106 99 90 1.154 1932 96 128 211 107 81 101 92 95 110 105 102 125 1,353 1933 111 126 188 133 106 97 78 83 90 86 80 87 1.265 San Francisco wholesale market 1931 1932 30 30 63 435 481 586 * Data from: Fruit and vegetable unload summaries. Federal-State Market News Service, Los Angeles and San Francisco annual issues. (Mimeo.) Santa Barbara County stations, and a few other minor stations. The total acreage, production, and farm value of spinach grown for market in California for the years 1929 to 1934, inclusive, are given in table 2. Similar data for the California canning spinach crops are given in table 3. TABLE 2 Acreage, Production, and Farm Value of Spinach for Market in California FOR the Yfars 1929 to 1934* Production, Yield per acre. Total farm value. Price per bushel, dollars Year Acreage 20-pound bushels bushels dollars 1929 1,400 1,085,000 775 434,000 0.40 1930 850 640.000 753 275,000 .43 1931 1,000 760,000 760 296,000 .39 1932 930 618,000 665 247,000 .40 1933 1,100 845,000 768 296,000 .35 1934 1,300 800,000 615 312,000 0.39 * Data from: Summaries of vegetable acreages. California Cooperative Crop Reporting Service. Sacramento, annual issues. (Mimeo.) California Agricultural Extension Service [CiR. 92 Most of the acreage for canning is located in Santa Clara, Alameda, and Monterey counties, followed in order by Sacramento, San Joaquin, Stanislaus, and Yolo, with a smaller acreage in southern California and a few other small scattered acreages. The acreage of spinach for canning by districts for the years 1928 to 1934, inclusive, is shown in table 4. TABLE 3 Acreage, Production, and Farm Value of Spinach for Canning in California FOR THE Years 1929 to 1934* Production, Yield per Total farm Price per Total pack. Year Acreage tons acre, tons value, dollars ton. dollars cases t 1929 15,790 90,000 5.7 1,382,000 13.35 4,193,743 1930 8,370 36,000 4 3 515,000 14 30 1,565,496 1931 5,850 28,700 4.9 379,000 13 21 1.339,700 1932 4,040 16,000 4.1 180,000 10 84 816,620 1933 8,200 32,000 3.9 319,000 9.98 1,587,839 1934 13,420 37,600 2.8 415,000 11 03 1,899,731 * Data from: Summaries of vegetable acreages. California Cooperative Crop Reporting Service, Sacramento, annual issues. (Mimeo.) t Data from published reports of Canners' League of California. TABLE 4 Acreage of Canning Spinach in California by Districts FOR the Years 1928 to 1934* District 1928 1929 1930 1931 1932 1933 1934 Average Santa Clara and San Mateo . 2,891 1,897 875 2,433 2,897 2,462 762 3,036 360 562 2,551 1,072 320 1,672 2,166 1,834 282 1,501 60 203 1,386 50 280 605 1,679 1,473 217 1,203 855 739 365 907 1,814 1,119 723 1,627 13 265 1,439 403 240 555 2,815 1,809 1,733 2,536 138 335 2,550 467 23 1,009 2,172 1,619 Monterey, Santa Cruz, and San 708 Sacramento and Yolo 1,892 82 Sutter, Butte, and Yuba . 350 1,827 765 250 1,055 245 Stanislaus, San Joaquin, and 952 746 1,636 Tulare and Fresno 394 260 70 200 227 4.039 225 Los Angeles, Orange, and Ventura 742 Totals 12,343 15,784 8,367 5,854 8,198 13,415 9,714 * Data from: Acreage of specified commercial vegetable crops by counties, California. California Co- operative Crop Reporting Service, Sacramento, annual issues. (Mimeo.) CLIMATIC AND SOIL REQUIREMENTS Spinach, a cool-season crop, will withstand freezing temperatures. It makes its best growth during cool weather, but goes to seed rapidly dur- ing warm weather and long days. Germination of the seed occurs readily at 40° F and below, with good germination from 50° to 60°, and with a decreasing percentage of germination at temperatures higher than these Spinach Production in California 7 The poor growth of spinach during warm weather limits its produc- tion in the Great Valley and Imperial Valley to late fall, winter, and spring. In the coastal regions it may be grown the year round, but the best-quality product is secured during the cooler parts of the year. The canning crop is grown principally during the winter and early spring, with a small acreage in the fall. Spinach will grow well on a wide range of soils, but fertile heavy loams usually give higher yields than lighter soil types. Well-drained river-bottom or lowland soils are excellent. Spinach will make a fair growth on soils containing too much sodium chloride for most other crops. It will not not survive when submerged under water for any length of time. When it is grown during the rainy season, the land should be fairly level and well drained. Spinach is sensitive to the acidity or alkalinity of the soil. On highly acid soils, whose pH value is lower than 5.5, low germination, yellowing of the tips and margins of the seedling leaves, killing of the roots, death, or a poor growth of the plants may result. On soils that are too strongly alkaline, the yellowing of the leaves referred to as chlorosis may occur. This results from a deficiency of available iron, manganese, or other mineral elements in the soil at that reaction. A soil reaction close to neutral, preferably slightly on the acid side (pH 6.2 to 6.8), has been found to give the best results with spinach. CROP ROTATION Since spinach requires only a short growing season, usually 70 to 100 days during the cooler parts of the year, it fits well into rotations with other crops during a season. When spinach is grown in small acreages by market gardeners, more than one crop of spinach may be grown on the same piece of ground during one season. The crop preceding spinach should be kept free from weeds, as hand- weeding the spinach is exceedingly expensive. For this reason, spinach should not follow a grain or forage crop. Morning-glory is ordinarily not a troublesome weed during the time this crop is grown. When weed growth in a canning crop is heavy at harvest time, the entire field or por- tions of it may have to be abandoned because of difficulties in harvesting. When only one crop of canning spinach is grown in a season, a com- mon practice is to place the spinach between crops of canning tomatoes. Any other warm-season crop, such as beans, that would not occupy the ground from the middle of November until the middle of April might also well be used in rotation with spinach for the cannery. Spinach is often interplanted between young trees, young asparagus plantings, or wide-spaced root-vegetable seed crops. California Agricultural Extension Service [Cm. 92 FERTILIZER PRACTICES Commercial fertilizers are not commonly used for spinach in this state, except as incidental to the fertilization of other crops. The feeling that such a practice would be profitable, however, is growing. According to results in eastern sections where spinach has been produced for a long period, chemical fertilizers, properly applied, are very profitable. To be of highest quality, spinach should grow rapidly and luxuriantly and should have a good green color. For this type of growth a supply of nitrogen in a readily available form is necessary. Soils of low fertility generally respond to the addition of organic material and nitrogen. Organic material may be applied profitably by means of a covercrop or by the addition of barnyard manure, bean straw, or other similar organic fertilizers. Some growers use from 10 to 20 tons of barnyard manure per acre for this crop. To supplement the addition of organic material or to enrich the soil in cases where covercropping and organic manures are not available, chemical fertilizers should be applied in generous amounts. Judging from fertilizer tests conducted on vegetable crops, particularly in southern California, a combination of inorganic nitrogenous fertilizers — for example, a mixture of 250 pounds of sulfate of ammonia and 500 pounds of fish meal per acre — give excellent results, especially if applied to the land before the crop is planted. Inorganic materials such as sulfate of ammonia, nitrate of soda, nitrate of lime, or cyanamid have also been used successfully, especially in combination with covercrops or barnyard manure. They may be applied broadcast before planting, placed below the seed in the planting operation, or used as a side dressing in one or more applications in amounts sufficient to add from 60 to 100 pounds of nitrogen per acre. This last method will probably give the best results. In the case of sul- fate of ammonia one must apply about 500 pounds per acre to add 100 pounds of nitrogen. Complete fertilizers are still being used to some extent on spinach, as on other vegetable crops. As experimental data in California have dem- onstrated, however, these fertilizers are no better than applications of nitrogenous materials when comparable amounts of nitrogen are added, and they generally cost more per pound of plant food. The amount and type of fertilizer that can profitably be applied varies with different soils and under different conditions and must be determined locally by trial. When spinach shows slow growth and poor color, an application of an available form of nitrogen is justified, Spinach Production in California 9 although in some cases the trouble may be more complicated than simply a lack of nitrogen. Animal manures, if available at a low cost per ton, may well be used on all soils. VARIETIES The varieties of spinacli are usually divided into several classes according to shape of seed and type of leaf. Spinach seed is either round or prickly; most varieties have seed of the former type. The marketable leaves of spinach are relatively smooth and flat, or crinkled or savoyed. The flat-leaved varieties are used almost exclusively in California both for canning and market, whereas the savoy types are used principally in the eastern sections and in Texas. Prickly Winter. — Improved strains of this old type are the most im- portant for use in this state. Strains vary considerably as to earliness, size of plant, color, and length of time between attaining maximum size and shooting to seed. All are flat-leaved, have prickly seed, and are very hardy. Hollandia is the name given to early strains of Prickly Winter that have proved most satisfactory for canning in the Sacramento and Santa Clara valleys. Amsterdam Giant strains are later, smaller strains, too slow-growing for best canning use. They may be better suited for late spring and summer planting than the former. Viroflay. — The variety Viroflay is preferred by some to the Prickly types. It is round-seeded and flat-leaved, and matures in point of time between Hollandia and Amsterdam Giant. Viroflay does not have such large leaves as Prickly types, tends to have longer petioles, and is not a long-standing type. Under favorable conditions it probably will not yield so high as Hollandia. Nohel. — This variety, also called Long Standing Gaudry, is a recent introduction, which has been very successful in the East, but has not been satisfactory for a spring crop in this state. It is recommended for trial, however, if spinach is to be grown during warm weather. It is a round-seeded, flat-leaved, long-standing type. Bloomsdale Savoy. — Although the most important of the savoy-leaved types, Bloomsdale Savoy is not used to any extent in this state. It is not used for canning here, but is a high-quality, rapid-growing variety, suitable for market and the home garden. Long Standing Bloomsdale, a later strain, will stand more warm weather without going to seed. It is therefore recommended for home-garden planting during warm weather. Virginia Savoy and Old Dominion. — These are ''blight" or mosaic- resistant varieties used principally for fall planting in the East. They 10 California Agricultural Extension Service [Cm. 92 Fig. 2. — Methods of planting spinach. Upper : a field of young spring can- nery spinach planted on the flat, near Sacramento. Center : fall canning spin- ach planted on lettuce beds, near San Juan. Lower : market spinach on beds, Los Angeles County. The beds on the left were planted dry and are just being irrigated. The spinach on the right is nearly ready for harvest. Spinach Production in California 11 are recommended for trial for market use wherever "blight" or mosaic is a limiting factor. Most of the spinach seed used in this country is produced in Holland. American-grown seed, though of equally good quality, cannot be pro- duced so cheaply nor so easily. CULTURAL PRACTICES Soil Preparation. — For a good crop of spinach, a well-prepared seed bed is important. The land should be plowed deep, and any refuse from the previous crop should be well turned under. After plowing, the land is commonly disked, harrowed well, and floated if not smoothed suffi- ciently by harrowing. Most growers prefer to plow the land in the fall when dry, working it after the first rains. Planting. — Spinach may be planted either on the flat or in double rows on lettuce beds. Nearly all the winter and early-spring acreage is planted on the flat, whereas the late spring, summer, and fall plantings for market are usually planted on raised beds to facilitate irrigation. A greater use of raised beds is probably justified, since they provide better drainage during wet periods and facilitate irrigation in case of insuffi- cient rainfall. For the different methods of planting, see figure 2. When spinach is grown on the flat, the seed is ordinarily drilled in rows 12 to 20 inches apart, 16 or 18 inches being the most common dis- tances. For the larger acreages a four-row bean or beet planter of the shoe or disk type is used. This allows for cultivation with a two or four- row cultivator. For smaller areas the planting is commonly done with a single-row drill-type hand-planter. If cultural practices are to be car- ried on with tractors, the rows must be spaced accordingly. When planting on the flat, some growers prefer to work the soil and plant while it is dry, allowing the first rains to germinate the seed. Others complete the preparation of the seed bed and plant after the first rains. The latter system has the advantage of destroying the large number of weeds that spring up after the first rain, which may be an important factor on weedy land. When planted on beds during the dry season, the seed is usually placed in dry soil and irrigated up. In this case sled-type planters like those used for lettuce are employed. A four-row, two-bed sled planter is shown in figure 3. Time of Planting. — The winter-spring canning crop is sown from the latter part of November to the middle of January. Most growers prefer to plant during December if possible. The fall canning crop in the Salinas Valley is usually put in during September, although plantings may be made continuously up to the middle of December. 12 California Agricultural Extension Service [Cm. 92 Spinach grown for market may be planted the year round unless the weather becomes too warm. Plantings made during the dry season are put on raised beds and irrigated up, whereas those made during the wet season may be on raised beds or on the level and may require no irriga- tion. In regions where the weather is cool enough to grow spinach throughout the year, small plantings may be made at frequent intervals •^*» Fig. 3. — Equipment used for seeding spinach and lettuce in the San Fernando Valley. This equipment is generally homemade or built by the local blacksmith. to provide a continuous supply; during the spring and summer months, plantings of smaller areas should be made at more frequent intervals than during fall and winter. This procedure is necessary because the spinach that matures during the summer and early fall w^ill not remain in marketable condition so long as that which matures during the cooler months. Amount of Seed to Plant. — For the canning crop, 8 to 15 pounds of prickly seed or 8 to 10 pounds of round seed per acre is used. The amount required depends on the spacing of the rows and the desired spacing of the plants in the row. The smaller figures probably represent the better amounts to be used for a canning crop if planted under con- ditions favorable for germination. Heavier plantings tend to crowd the plants excessively, making them small, spindly, and more difficult to handle in the cannery. Plants spaced about 2 inches apart in the row will probably produce the most satisfactory product for canning as well as the highest total yield. Thinning of the plants is not practiced. Spinach Production in California 13 When the crop is grown for the market, more seed is usually planted — as much as 25 to 30 pounds of the prickly and 20 to 25 pounds of the round seed per acre. In this case the plants are harvested when small and sold by the bunch, and the crowding mentioned above may be advantageous. Seed Treatment. — When losses from damping-off may be expected to cause poor stand, the seed should be treated before planting. This is best done by shaking the seed with red cuprous-oxide powder at the rate of Fig. 4. — Cultivating spinach with a four-row riding cultivator. Tin guards are used to prevent covering the small plants with soil. A flat, shallow weed cutter on each side of the row is used. a teaspoon of the powder to each 50 pounds of seed. The seed should be shaken with the powder until each seed is covered with a fine coating of the dust. The dusting of cabbage seed with a mixture of equal parts of mer- curous chloride (calomel) and wheat flour has proved helpful in con- trolling the cabbage maggot on plants in the seed bed. This treatment has been tried by several Los Angeles County growers on spinach seed for the control of the seed-corn maggot. The results so far have been fairly satisfactory. The treatment is recommended when replanting fields in which the stand has been destroyed by the seed-corn maggot or when planting fields known to be infested. A thorough coating of the seed with the dust mixture is essential. Crust Prevention. — With soils that tend to form a hard crust it may be necessary to go over newly planted acreages with a roller after a rain. This should be done only before the seedlings have emerged or while they are still small. 14 California Agricultural Extension Service [Cm. 92 Cultivation. — Spinach plants have a much-branched, spreading root system, with the majority of the feeding roots from 2 to 10 inches below the soil surface. Cultivation must therefore be very shallow, especially after the plants reach some size, and should be practiced only when weed control is necessary; two or three cultivations are usually given. Shallow weed cutters are used, with a two or four-row riding cultivator, a hand wheel-hoe, or special implements designed for use on raised beds. A four-row horse-drawn riding type is shown in figure 4. Cultivation to form a soil mulch after a light rain may do more harm Fig. 5. — Irrigating late spring canning spinach with an overliead sprinkler system. A tractor furnishes power for the pump. Photographed near Sacra- mento. than good for it may cause a greater loss of moisture; it is primarily for the purpose of weed control. Irrigation. — Spinach should grow rapidly and without a check until harvested. It therefore requires an adequate supply of moisture through- out its season. Since the root system is confined mainly to the upper foot of soil, frequent rains or frequent irrigations are necessary for maximum production, especially with light sandy soils of low water-holding capac- ity. Crops planted on raised beds may be irrigated by the furrow method if the land is sufficiently level. This is the usual practice with late spring, summer, and fall market crops. The canning crops planted on the flat depend on rainfall for their moisture. Often this is insufficient for best growth during March and early April. Within the last few years some growers have used a port- able overhead sprinkling system (fig. 5) with success. As the margin of profit in growing spinach for the cannery is usually small, this added expense should be avoided by earlier planting and by selection of soils with a better moisture supply if possible. Overhead sprinkling may also cause an increase and spread of downy mildew. Spinach Production in California 15 HARVESTINa FOR THE CANNERY Time of Harvest. — The winter-spring crop of canning spinach is usually harvested in the Santa Clara Valley from March 10 to April 1, and in the Sacramento district from March 15 to April 15. The fall crop in the Salinas Valley is harvested from December 15 to April 1. Fig. 6. — A two-row spinach cutter popular in the Santa Clara Valley. This cutter is light, cuts at a uniform depth below the soil surface, and is easily guided. Methods. — Spinach for canning is harvested in two ways. One may either harvest the entire plant at one time by cutting the root slightly below the surface of the soil, or remove only the larger leaves, allowing for a second and possibly a third crop of leaves to develop. The former system is used almost exclusively in the Santa Clara and Sacramento valleys. The latter is generally followed in southern California and to some extent in the Salinas Valley. When the entire crop is removed at one time, the cutting may be done with various types of horse-drawn cutters or by hand with flat push hoes. The former method is generally used. Growers in the Santa Clara Valley have developed an all-iron, cultivator-type, two-row cutter drawn by one horse with a man walking behind to guide it. This type of cutter, though especially adapted to the heavy soil types in that district, works equally well on lighter soil types. These cutters (fig. 6) are made and 16 California Agricultural Extension Service [CiR. 92 offered for sale locally in San Jose. In the Sacramento area two-row sled- type cutters, drawn by one horse with the driver riding, are commonly used. A battery of such cutters is shown in figure 7. Four-row riding m . ^S^^!j* ^m %^ ^^n ^^^^^f ^|MM|pg| MM|||. m ' '^^^P^S ^H ~i^^^LSidi<>^ le^fl^^H •' JHI IK ^ .ff,"*^^ ,^ 'fci-*j|^M| m lliili'iiiiiiiTj '^''^^'^i^llllilV -^^ f^ii i^^^«f «™JIi^i«.i*^JS ^fflin '^^i^'^^MsB^r^m^'^^ ^K^M 9^pP^. fflmmV ^g^3|^^lB pi ^y '' » 1 ^Kj^^j^^^^HEHj ^H IKlBi^^^^^^B^^Kj^^jy^! ^^ ^.,,^,->^ * *»». iftlirliflr Hh VMI nIhhHHIII IBiBiil ■^^**WI^^II^^^X>^^^^^P<| HH ^i^^^m Hum jfex^%jiBlprlSBfec^^**^^Hill H I^M ^H II^^MHllKs^^^BHHKr^ In BB0 SHHI bh Fig, 7. — Two-row sled type of spinach cutter used largely in the Sacramento district. The cutter at the left is elevated to show the position of the cutting blades. ^^^^^^^^BmJ^M ra^ra^i^^^^^i^^^^R T^^WT'^ ^^^S^S^^^^^m^^^m Fig. 8.^ — Cutting spinach by hand in a weedy field near Sacra- mento. Note the large number of cutters used when the cutting is done by hand. cultivators with properly placed knife blades and guards may also be used. Harvesting spinach by hand is shown in figure 8. The harvesting procedure is simple. The plants, having been cut, are gathered by hand and placed in field crates supplied by the cannery and holding from 50 to 70 pounds of spinach. The crates are placed in rows in the field, loaded on trucks by hand, and delivered to the cannery as Spinach Production in California 17 soon as possible. If the spinach is to be delivered in good condition, it must be picked up and placed in crates as soon as possible after it is cut. That is, the horse or hand cutters should not get far ahead of those plac- ing it in the crate, especially if the weather is warm. Fig. 9. — Implement used in southern California to cut canning spinach above the ground. Either the crop is harvested under contract at so much per ton, or the workers are hired directly by the grower on an hourly wage basis. The former practice is more general. In this case individual workers are paid by the contractor according to the number of crates they fill, but the cutting is done by the grower. The size of the crew required for harvesting varies with the acreage to be harvested and with the yield obtained. Under the most favorable conditions one man can pick up nearly 2 tons per eight-hour day, but the average is nearer IV2 tons. One two-row horse-drawn cutter will keep 15 to 20 men busy placing the spinach in crates. When the cutting is done by hand one cutter is required for each 8 or 10 men. 18 California Agricultural Extension Service [CiR. 92 When the plants are cut above the ground, as in southern California, a large straw fork with a V-shaped knife inserted in the center and with upright tin sides and back for catching the cut leaves, or a modification m^ m$ WILl ms. :J ^M ip V X ■ "^ . ,fi ^m^ mm m-m. *-'i*, i,^-'- mm JliISi ■^- *-r< i I' ^1 ^m f:*^^ ^' ^y'Z^^-% 'miM IIH Fig. 10. — A spinach-harvesting scene in the San Fernando Valley near Van Nuys. This field produced 14 tons of spinach per acre. This is the first crop; the second crop was obtained in February of the following spring. Fig. 11. — Spinach may be cut aboveground by hand, using a small knife. The loose leaves are sorted and trimmed in the field ready for canning. of this idea, is used (fig. 9) . The fork is pushed along astraddle the row, the plants are cut just above the ground, and the leaves are gathered until the fork is full. The loose leaves are then dumped into a crate pulled along by a partner, and the crates hauled to the cannery as soon as pos- sible (fig. 10). If the crop is grown on beds, the leaves may be cut with Spinach Production in California 19 a large knife (fig. 11). Then the loose leaves are gathered by hand and placed in crates. This system is not generally used. The presence of large weeds, such as mallow or mustard, is a serious handicap in harvesting. It may even necessitate abandoning the entire Fig. 12.— A field of canning spinach near Sacramento with a heavy gro-wth of volunteer grain which completely obliterated the rows. This field was abandoned after a small portion had been cut, because of difficulties in harvesting. Fig. 13, — A field of canning spinach near Santa Clara with a heavy growth of mallow. A part of this field was harvested, but the largest part was abandoned because of the weeds. crop or portions of the field where the weed growth is heaviest (figs. 12 and 13). For this reason land free from weeds should be selected for growing spinach for the cannery. Yields. — The average yield of canning spinach for this state for the years 1931, 1932, 1933, and 1934 has been 4.9, 4.1, 3.9, and 2.8 tons per acre respectively. These figures do not represent what are considered good yields of spinach nor average yields in the better areas. A yield of 20 California Agricultural Extension Service [Cir. 92 5 to 6 tons per acre may be considered as average for the better districts, with yields of 8 to 10 tons fairly common, and 12 to 15 tons considered very good yields. The prices to the grower for the same years averaged $13.21, $10.84, $9.98, and $11.03 per ton respectively. Fig. 14. — Spinach bunched, crated, and ready for delivery at the market the following morning in Los Angeles. HARVESTING FOR THE MARKET Fresh spinach is sold by the bunch, by the pound, or by the crate of four or five dozen bunches. When the plants are to be bunched, they are usually pulled by hand from moist soil and tied in bunches of four to eight plants, according to their size. The tap roots may be trimmed off, but usually are not. The bunches are thoroughly washed to keep them fresh and turgid. Harvesting is usually done in the afternoon to permit delivery to the market early the next morning. Spinach ready for the market is shown in figure 14. In harvesting by hand for the market a common practice is to go over the patch several times, removing only the larger plants at the first pickings. Spinach for market may also be cut underground with a push hoe, and the plants placed loosely in crates and sold by the pound. If the acreage to be harvested is large, the cutting may be done with a horse- drawn cutter; but this procedure is not common unless the crop is to be shipped in carlots to distant markets. When the field is cut by hand, the areas with the larger plants are cut first (fig. 15) . Spinach Production in California 21 In preparing spinach for the fresh market, one should remove all yellow or dead leaves, as well as all plants or parts of plants damaged by insects or disease. All market spinach should be harvested before seed stalks appear; the market preference is for young, small, tender plants with small stems and roots. When shipped to distant markets, the spinach is placed in paper-lined lettuce crates, preferably loose and unwashed; a shovelful, or about 10 pounds of crushed ice is added; and the crate is sealed and shipped under refrigeration. Carlot shipments of spinach under refrigeration are relatively unimportant in California. Fig. 15. — A field of market spinach near Sacramento. Note how irregular the course of harvesting has been. The plants were cut below ground with a push hoe or knife. Yields of 600 to 800 crates per acre are common. The market price varies from 30 to 70 cents per crate, according to the season. Average yields and returns are given in table 2. DISEASES AND THEIR CONTROL Spinach is attacked by few serious diseases, but because of its habit of growth and the nature of the diseases, satisfactory control measures are not available. Downy Mildew. — This mildew, sometimes called leaf-mold or blue- mold, and caused by Peronospora ejjusa, is the most serious disease of the spring spinach crop. It may be absent in certain seasons; but under favorable conditions it may appear, spread rapidly, and destroy whole fields, particularly for canning. It may also be present on the fall crop. The disease is manifested by pale-yellowish spots on the leaves, vary- ing in size from small to fairly large. The lower leaves are ordinarily attacked first, but the disease may be scattered over the entire plant. The spots are usually bare on the upper surface of the leaf and covered with a gray to violet-gray mold on the underside. This is the sporulating 22 California Agricultural Extension Service [Cib. 92 fungus tissue. The affected parts decay or dry up, and the whole leaf may soon succumb. In severe cases the entire plant may be affected. Under favorable conditions of temperature and humidity the fungus fruits abundantly. The spores are splashed by rain or blown by the wind to other plants, and thus the spread of the disease is very rapid. Although the spores require free moisture and a temperature of 40° to 50° F for germination, they will continue to grow at higher tempera- tures. The disease is therefore most destructive during a rainy or foggy Fig. 16. — Spinach plants affected with mosaic or "blight." From left to right are a plant infected at a fairly late stage, a healthy plant, and three plants infected when small. period when the nights are cool. Drying winds and temperatures con- tinuously above 50° or below 40° will check the development and spread of the downy mildew fungus. Thick- walled resting spores, capable of liv- ing from one crop of spinach to the next, are formed in the tissue killed by the disease. They serve as a source of infection each fall and spring. Copper salts are very toxic to the spores. For satisfactory control, however, the foliage would have to be covered before the appearance of the disease and kept covered throughout the infective periods. Since one cannot predict when the disease will appear, and since it may be natu- rally checked at any time by warm weather and drying winds, control measures are not considered practical. Any sanitary measure, such as crop rotation and plowing under deeply all diseased plant refuse, may help avoid the occurrence of the disease. The development and use of resistant varieties is the most satisfactory means for preventing losses from this disease. The flat-leaved prickly types generally used in this state are the most resistant of the commer- cial varieties. Further breeding work is, however, required to develop more highly resistant selections satisfactory for canning and market. Spinach Production in California 23 Mosaic. — The disease commonly called "blight" or yellows, is a seri- ous trouble of the fall crop in central and northern California and of the fall and spring crops in southern California. It is not a factor in the spring canning crops of the Santa Clara and Sacramento valleys. Mosaic is one of the so-called virus diseases, the nature of which is not known. The first symptom is a slight mottling of the small inner leaves, which later turn yellow and finally die. The outer leaves finally turn M^iMlteMK:. '... ^... ;.^*-% a ^ 1 fillBl^lHIiiii^ p*-^^^^^^^^^S«^^M^^^^^^P^^^^^^^^^^&t^^^^^ ^^^^•«^ ~ ^^^^s^f^^mm^^ ' - «f j?*?^- -. Fig. 17. — A field of fall market spinach near Racramento in which nearly all plants were unmarketable because of mosaic. yellow and may become curled and wrinkled. If the plant is affected when young, it remains much dwarfed and finally succumbs (fig. 16). Older plants are less severely affected, but may be made unfit for mar- ket. In severe cases, entire fields may be an almost total loss (fig. 17) . Spread of the disease in the field is by the feeding of aphids, or plant lice, on healthy plants after previously feeding on diseased plants. A small number of aphids may spread the disease rapidly, so that control of the disease by spraying or dusting is impractical. As mentioned before, the savoy-leaved varieties, Virginia Savoy and Old Dominion, are resistant to mosaic. Unf ortuntely they are not suited to the market or canning needs of this state. The development of suitable resistant varieties is now^ under way. Curly Top. — A common virus disease of beets, curly top, may also affect fall spinach crops. The plants are affected more severely than beets, and serious losses may occur in a short time. The virus is carried by various leafhoppers, and infection is accomplished by their feeding. 24 California Agricultural Extension Service [Cim. 92 Infected plants show progressive yellowing of the leaves from the younger to the older, with killing of the inner leaves and eventual death of the entire plant. Affected plants are unfit for market even though they may not be killed. The disease may be confused with mosaic or blight. The curly-top disease may be expected to occur wherever leafhoppers are found, particularly in the vicinity of sugar beets. There are no suitable control measures except to avoid planting spinach in localities where, or at the seasons when, infection may occur. Malnutrition or Physiological Trouhles. — Various physiological troubles may cause yellowing and poor growth of spinach plants. These troubles are discussed under soil requirements. INSECTS AND THEIR CONTROL Spinach is relatively free from the serious attacks of insects. Aphids. — Green plant lice, or aphids, may be troublesome on the fall or late spring crop. When sufficiently numerous they may injure the plant by direct feeding; they cause a curling of the leaves and stunting of the plants. They do more damage, however, as carriers of the mosaic virus and by attracting the larvae of the syrphid fly. These larvae, com- monly called "worms," are predaceous feeders on the adult aphids. They are whitish, green, brown, or striped in color and % to % inch long. Aphids may be washed from spinach during the canning process, but the larvae cling tightly to the leaves when immersed in water and can- not be removed. Aphids on canning spinach at any time after March 1 may attract the syrphid fly larvae. The presence of even a small number of the larvae or "worms" may cause the spinach to be rejected at the cannery and the crop abandoned in the field. Aphids are not common on the early spring canning crop but may appear if harvest is delayed until after the weather warms up. They may be controlled with a nico- tine dust, but this method is not practicable on spinach, especially near harvest time. Spinach Leaf Miner. — The leaf miner {Chortophila hyoscyami Pan- zer) may infest summer and fall crops but does not appear early enough in the season to infest the spring canning crop. The small gray flies lay their white eggs in April and May on the undersides of the leaves. The maggots emerge in four or five days, work their way into the leaf be- tween the two outer layers of tissue, and there excavate their mine, causing an irregular blotch. The maggot deserts the leaf after a week to fifteen days and enters the ground for pupation. Several generations Spinach Production in California 25 may appear during the summer. The maggots may be seen in the blotch if they are in the leaf. There are no satisfactory field control measures. Field sanitation and crop rotation may help; but growing the crop during the late fall, win- ter, and spring is the best way to avoid this insect pest. Seed-Corn Maggot. — The late fall spinach crop may be infested with the seed-corn maggot {Hylemia cilicrura Rond), sometimes called the spinach-bud worm. The maggots feed only in the portion of the plant that is in the ground or in the lower portion of the stem and upper por- tion of the root. Small seedling plants are especially susceptible to attack and are easily killed. Growers in southern California have experienced occasional severe losses from this pest. Several entire 10-acre fields were destroyed in Los Angeles Count}^ during the fall of 1934, and losses have been suffered in previous years. Reseeding with seed treated with the mercurous chloride as outlined in the section on seed treatment appar- ently gave results, for an excellent stand of plants was obtained and a satisfactory yield secured. Very few experimental data on the seed-corn maggot are available. Diabrotica or Cucumber Beetle. — This beetle may cause some damage to fields of spinach during the early life of the plant. The damage that has occurred has been largely done by the larvae, which live and feed within the upper portion of the root and the lower portion of the stem. These insects destroy seedling plants very quickly. In addition to the common Diabrotica soror and the Diabrotica trivittata we now have the Diabrotica balteata, a recent addition to the insect kingdom in southern California. CULTURE OF NEW ZEALAND SPINACH New Zealand spinach (Tetragonia expansa) is an entirely different plant from true spinach. It grows in a sprawling manner, and only the tips of its many branches are harvested for use. Since it thrives only during hot weather, it can be used when true spinach is difficult to grow. Its chief use is for the home garden, although it may be grown on a small scale for the local market. The crop is started from seed sown in the field during April or May. The seeds are large and have a hard coat. Soaking them for 24 hours in warm water before planting hastens germination, but even then the plant may not appear for two weeks or more. An abundance of moisture is required for germination. Since the plants have a spreading habit of growth, the rows should be spaced 3 to 4 feet, with the plants a foot apart in the rows. The crop requires a deep, fertile soil and responds well to manuring 26 California Agricultural Extension Service [C'ir. 92 and fertilizers. One or two applications of nitrate of soda durin<>' the summer may stimulate succulent new <>rowth. Only the tips of the Fig. 18. — Only the young, succulent tips of New Zealand spinach are harvested. branches (fig. 18) are harvested. As the tip of each branch is removed, more lateral branches develop, so that production continues throughout the summer. The tips may be sold loose by the crate, or tied in bunches of 6 to 8 inches in diameter and sold in crates by count. ACKNOWLEDGMENTS The author is indebted to F. H. Ernst, Assistant Farm Advisor of Los Angeles County, for information on fertilizer practices, for methods of controlling seed-corn maggot, and for figures 3 and 10. 14m-8,'35