R. H. SCIARONI^ P. A. MINGES W. H. LANGE W. C. SNYDER A. ^ggjf" CALif ORNIA AGRICULTURAL Experiment Station -n Service CIRCULAR 427 The end of the road for the grower— here a hand- truck load of Brussels sprouts is weighed in at the packing shed after being trucked from the farm. PREPACKAGED SPROUTS AND FROZEN PACKS are becoming increasingly popular in the California market. During the past few years more than 50 per cent of the California production has been processed by the freezer industry. As much as 85 per cent of the San Mateo County crop moves to the freezers. THE VALUE OF THE CROP for the past eight years has been between three and four million dollars annually. During 1950 and 1951 the California frozen pack amounted to approximately 20 million pounds each year. Brussels sprouts are expensive to produce, principally because of the long growing season and the high labor requirement of harvesting. IF YOU LIVE NEAR THE COAST you may be able to grow sprouts, which need relatively cool temperatures for best quality and yields. THE AUTHORS: R. H. Sciaroni is University of California Farm Advisor in San Mateo County. P. A. Minges is Extension Vegetable Crops Specialist, Davis. W. H. Lange, Jr., is Associate Professor of Entomology and Associate Entomologist in the Experiment Station, Davis. W. C. Snyder is Professor of Plant Pathology and Plant Pathologist in the Experiment Station, Berkeley. BRUSSELS SPROUTS PRODUCTION IN CALIFORNIA R. H. SCIARONI W. H. LANGE, Jr. P. A. MINGES W. C. SNYDER PLANTING and GROWING THE CROP Xhe coastal districts of San Mateo, Santa Cruz, and Monterey counties produce most of the California crop of Brussels sprouts. Annual plantings here reach 4,000 to 5,000 acres. A small acreage is grown in the Arroyo Grande district of San Luis Obispo County, and occasionally plantings are made in other coastal counties. Most of the Brussels sprouts for the frozen pack and about % of the output for fresh market and a small amount for canning are grown in California. The next largest producing district is in Suffolk County, Long Island, New York, where about 500 acres are planted each year. Scattered plantings are found in the Pacific North- west, New Jersey, Connecticut, and a few other states. What varieties to plant The principal variety of Brussels sprouts planted in California is appar- ently a selection of Half Dwarf. A plant of medium height that produces firm sprouts is desirable, but in these respects the present seed stocks are quite variable. Most of the seed is produced by growers for their own or their neighbors' use. A new variety, 50A, has recently been developed by one of the seed firms. Plants are relatively uniform and produce good- quality sprouts of a darker green color than the type being used. Tests conducted in San Mateo County indicate that this variety is well adapted to the central coast districts. When and where to plant Brussels sprouts, like other members of the cabbage (Crucifer) family, reach best quality if the crop develops and ma- tures during cool weather. A 4-to-5- month harvest period with relatively cool temperatures is needed for good yields. Reasonably high humidity during the period may also be beneficial. Warm weather causes the formation of soft or open sprouts, while the production of any sprouts is stopped by average tempera- tures somewhat below 50 °F. Accordingly, the exposed coastal districts of California afford the best growing conditions in this state. In the main Brussels sprouts dis- tricts, average monthly temperatures sel- dom rise above 58° F in summer, and the moderate winter temperatures seldom av- erage below 50 °F. Although this crop can be grown in other areas of the state, yields are usually rather low because of a relatively short season of desirable tem- peratures — early fall being too warm and late fall and early winter too cold. Brussels sprouts seed will germinate at soil temperatures of 45°F or higher. The plants will withstand frosts at any stage. The firmest sprouts are often formed dur- ing periods of light frosts and sunny days. [3] As this crop is a biennial, the plants will go to seed in the spring after being grown through the winter. Plants started too early in open seed beds may also go to seed later in the spring. This bolting problem tends to preclude spring pro- duction of Brussels sprouts in this state. In general, plantings made in late spring for fall and early-winter harvest are most satisfactory. Soils with both good surface and underground drainage are desirable, to avoid the hazard of drowning out the plants during periods of heavy rainfall. For this reason deep, sandy, or sandy- loam soils are often preferred, especially for winter production. In the central coast districts, decomposed granite soils are also popular. Heavier soils have been used quite successfully, particularly in winters of low rainfall, although some growers have expressed the opinion soft sprouts may result on some of the more fertile types. In winters of high rainfall, however, heavy-textured soils will likely give trouble because of poor or slow drainage and muddy conditions for har- vesting. Dates of planting and harvest In the coastal areas seed beds are planted from February to early April, the plants are transplanted into the fields during May, June, and early July, and the harvest season begins in late August or September. Plants are ready for trans- planting in about 75 days from a Febru- ary seeding, and in 45 days from April seedings. From transplanting to the first picking between 90 and 110 days are re- quired. Brussels sprouts are harvested in Cali- fornia from mid-August to early March. The picking season for a given field varies from 150 to 180 days depending on the season and the condition of the field. Peak production occurs generally during October and November. In areas away from the coast, a fair production of good-quality Brussels sprouts might be obtained during Oc- tober, November, and early December. In these areas seed beds could be planted in May and plants set in the field during July. How to care for your plants Fields can be established either by transplanting with plants grown in seed- beds or by field seeding. In California the usual method is by transplanting be- cause this allows more time to prepare the fields in the spring. Also in areas where cabbage maggots are a serious pest to the young plants, this insect can be more easily and cheaply controlled when the plants are concentrated in seed (plant) beds. A desirable transplant is 7 to 8 inches tall, free of disease, and has a stocky, tough stem the size of a lead pencil. From 6 to 13 weeks are required to grow transplants in open plant beds seeded during late winter and early spring. Grow transplants in open plant beds. Use well-drained soils free of dis- eases. It is good practice to locate seed- beds on new land or on land that for sev- eral years has not been planted to cru- cifers. Avoid locations known to be in- fected with the blackleg or clubroot diseases. An area of about 400 square feet is enough to raise plants for one acre. One pound of seed will provide enough good plants to transplant 5 to 6 acres. After the soil is prepared, the usual method of seedbed planting is to drill the seed in rows about 10 inches apart on the flat. Drill from 20 to 25 seeds per foot of row, and cover the seed with % to 1 inch of soil. With a little thinner seeding rate and therefore more space per plant, it might be possible to plant 7 to 8 acres from 1 pound of seed because there would be fewer small or weak plants to discard. Where seedbed land is limited or drain- age is poor, some growers prepare beds [4] 30 to 42 inches wide and 3 to 4 inches above the furrows. The seed is broadcast over the top of the bed. Weeding is diffi- cult with this method of seeding, and the plants may be too close for good growth. Keep the soil moist after seeding to promote rapid germination and emer- gence. Irrigation is generally provided by sprinklers. In some cases spring rains will supply moisture and reduce the num- ber of irrigations needed. If the young plants are very thick, thin them to pro- vide a spacing of 1 inch between plants. As the plants approach transplanting size they should be hardened by with- holding moisture. Pulling the plants. Two or three days before pulling, water the beds to reduce the amount of breakage while pull- ing plants. If any aphids are present, the beds should be dusted before pulling with a 2 per cent parathion dust. Do not prune either the roots or tops of transplants unless they are greatly oversized. Set transplants in the field as soon as possible after pulling. If this cannot be done at once, cover them with moist burlap and store in a cool place, preferably no longer than overnight. Only enough tillage should be done to dispose of crop residues and prepare good conditions for setting the plants. Disking or plowing followed by harrow- ing and floating are usual operations. In some fields leveling may be needed for efficient surface irrigation. Excessive till- age results in unnecessary loss of mois- ture and breakdown of soil structure. If you plan to use surface irrigation, open furrows either before or right after A two-row transplanting machine with water tanks attached. This machine will transplant sprouts and inject mercuric chloride-treated water into the root area. [5] planting; but if sprinklers are to be used, the land can be left flat throughout the season. If land cropped to Brussels sprouts the previous year must be used, it is neces- sary to cut up thoroughly the old woody stumps and turn them under. Several diskings and a deep plowing will usually accomplish this. Cornstalk choppers, with the blades refaced to strengthen them, have worked very well for cutting up the stumps. Row and plant spacing. The usual row spacing for Brussels sprouts is 36 inches. Plant spacing may vary from 28 to 36 inches, but 32 or 36 inches is the most common and the best for cross cul- tivation. A 36" x 36" spacing allows 4,840 plants per acre. Transplanting. Setting out trans- plants should not be attempted on warm, bright days, particularly if hot, drying winds prevail. The best times for plant- ing are cloudy days or cool, foggy morn- ings. Afternoon plantings are satisfactory if coastal fog or low clouds move in. Pro- tection against maggots in the field can be obtained by treating the roots and stems with chlordane (see Pest Control, page 9). Transplanting may be done by hand or with machines. In hand planting the fur- rows and beds are made first and the plants set about halfway up on the sides of the furrows. A short-handled hoe is used to make the holes, the plants are set 1 inch deeper than they grew in the plant bed, and the soil is firmed around the roots by hand. An irrigation should fol- low immediately after planting. With transplanting machines, which are generally used for the larger plant- ings, the ground is left flat, and furrows if needed are made at the time of plant- ing or shortly after. The opening shoe should be deep enough to permit setting the roots straight down, and the packers should be adjusted to firm the soil well around the roots. If plants are set with transplanters water can be supplied to each while planting, and it may not be necessary to water immediately after planting. Field seeding. Direct seeding in the field may have possibilities where mag- gots are not a problem and soil crusting is not serious. The field should be well leveled if furrow irrigation will be used for germinating the seed, and a better- prepared field may be needed than for transplanting. From % to 1 pound of seed will be required to seed an acre. The principal advantage of this method is that the plants are not set back by trans- planting, and therefore less time is needed from seeding to harvest. Also there is less danger of bringing diseases into clean fields. For a late August harvest, the field probably should be seeded in early April. The seed can be drilled in rows with Planet Jr. or similar planters at the rate of 4 to 6 seeds per foot of row. If the fur- row method is to be used the row should be near one edge of the bed to facilitate watering. Cover seed % to 1 inch deep. After the plants are up and well estab- lished they should be thinned to the de- sired stand. Crop rotation. Practice a crop-rota- tion program to prevent build-up of such diseases as blackleg and clubroot. Some growers rotate with such crops as arti- chokes, peas, lettuce, and horse beans. A rotational planting program can help to maintain good soil structure. Cultivation Cultivation is necessary to control weeds, establish permanent irrigation fur- rows, and sometimes to break up heavy crusts. One or more hoeings may be needed to control weeds around the plants. Fertilizers Requirements vary with soil type and previous soil management. Since Brus- sels sprouts are a slow-growing, long- season crop, the heavier, more fertile [6] soils can supply the required nutrients in adequate amounts. Fertilizers are more likely to be beneficial on sandy soils and other soils without much previous ferti- lizer history. Nitrogen is the main additional nutri- ent needed. No response to phosphorus or potash has been obtained in fertilizer tests conducted on this crop, though phosphorus may be beneficial on some soils. Many growers apply 10 to 15 tons of livestock manure or 5 to 10 tons of poul- try manure per acre; this is applied broadcast and worked into the soil before planting. In many cases the manure may take care of the fertilizer needs of the crop. Nitrogen can be supplied in commer- cial fertilizers such as ammonium sul- fate, ammonium nitrate, or anhydrous ammonia. An application of 60 to 100 pounds of nitrogen per acre will usually be adequate. This amount would be sup- plied in 300 to 500 pounds of ammonium sulfate per acre. At least Yz of the ferti- lizer should be applied shortly after planting and the rest during August or September. It can be placed in a band near the plant row or applied in the ir- rigation water as ammonia gas. Nitrogen and phosphorus can be supplied in ferti- lizers such as ammonium phosphate (16-20-0) or the mix 10-10-5. Irrigation Brussels sprouts are a shallow-rooted crop with few roots penetrating the soil below 2% to 3 feet. For good growth the plants must be supplied with plenty of water throughout the season. Two or three light irrigations are made about 4 to 6 days apart immediately after transplant- ing. After this, irrigations are made at about two-week intervals. Between 8 and 10 irrigations are necessary during the time from transplanting to the first fall rains. From 1 to 2 inches of water are applied per irrigation depending on the soil type. Most plantings will require Here a grower hoes weeds in a field of young sprouts. One or more hoeings may be needed to control weeds in the field. from 15 to 20 acre-inches of water in addition to fall and winter rainfall. Surface methods or sprinkling can be used. With surface irrigation, the first irrigations are applied in the furrows where the plants were set. After the first 3 or 4 irrigations new furrows are made midway between the rows. Growers with a limited water supply often use a com- bination furrow and flooding method, with the furrows spaced every 3 or 6 rows. Because most of the irrigation water in the sprouts districts is derived from small wells, impounding dams, reservoirs, and creeks, the large heads of water needed for efficient furrow irrigation are not available. Therefore sprinkler irrigation has become popular during the past sev- eral years along the coastal area because sprinklers may permit more efficient use of the available water supply. This method also has advantages on sloping land and other places where good leveling is impossible. Disadvantages of sprin- kling include a higher water loss due to evaporation and the difficulty of obtain- ing good distribution of water during windy periods. [7] OD a a> ;3 i - D I- 3 O D to CO w a to bo be CO Start dusting plants when flowers appear. Repeat dustings every 14 days during seed-pod formation. Soil : Dust on surface at rate of 100 lb. per acre. Rake into upper 2 inches of seed- bed before planting. Tops : Dust every 14 days at 40 to 50 lb. per acre starting when plants emerge. Dust just before transplanting to field. p! © pi •43 © M ft © w So % s cp! jj ■** S M Bt ■s * ©42 £p! IS* Do not apply chlordane or DDT after sprouts start to form or 30 days prior to harvest. Substitute DDD for the southern cabbage worm. New regulations allow the use of para- thion to within 15 days of harvest. Parathion is the most effective under wet, cool, coastal conditions. Repeat as needed. Concentrate at base of plants. "o 1 per cent crude benzene hexa- ] chloride dust 40 to 50 lb. OR 1 per acre 1 per cent lindane dust J 5 per cent chlordane dust, soil and top treatment OR 23^ per cent aldrin dust, soil and top treatment 2 per cent parathion dust, 40 to 50 lb. per acre 1 per cent lindane dust ] Dust roots and OR [ stems of plants be- 5 per cent chlordane dust J fore transplanting. 2 per cent parathion plus 5 per cent DDT ) OR 40-50 lb. 2 per cent parathion plus 5 per cent | per acre chlordane J 1 40 to 50 lb. per acre baits, or 10 per cent ►ounds per acre 2 per cent parathion dust OR 1 per cent TEPP dust OR 3.6 per cent free nicotine dust Arsenical-metaldehyde pelleted metaldehyde dust at 20 to 40 p M O O. »H O O CD CO OT V © © _ 'O »ej © -C © ft w<5 Maggots Aphids OT B Maggots Thrips Cabbage worms Aphids Aphids Slugs and snails be e8 CO O. O O © © OT M O «** OT -** Pi eo T3 © © © 09 OT +a Pi ft OT § Eh OT PI bflcpi § S >* Older plants during har- vest e3 ce >> 'o cp 1 EH March to June February to July Summer and Fall PESTS and DISEASES Pest control Insect control of Brussels sprouts is extremely important as the trade has de- manded a product low in insect damage and insect parts. Aphids are the most important insect pest of this crop. Several aphids occur on sprouts, the cabbage aphid (Brevicoryne brassicae) being most abundant. The bodies of cabbage aphids are covered with a white, powdery wax. During the early part of the season they feed on the leaves causing curling, distortion, and sometimes stunting of the plant. Some mi- grate to the sprouts as these are formed. It is very difficult to kill the aphids after they move into the sprouts, and it is al- most impossible to remove either dead or live aphids by washing. Materials for aphid control are para- thion, TEPP, and nicotine dusts. Start applications when aphids first appear. Frequent applications, at intervals of 15 to 20 days, are necessary for adequate control. Power-ground dusters offer the best method of applying the materials. A 2 per cent parathion dust applied at 40 to 50 pounds per acre is effective under low temperatures and wet condi- tions. TEPP is used as a 1 per cent dust at the rate of 40 to 50 pounds per acre. It is more effective under dry conditions than during wet weather. Nicotine dusts should contain from 3 to 4 per cent nico- tine as alkaloid and are more effective if formulated from nicotine alkaloid or "free" nicotine. Apply nicotine dusts at 40 to 50 pounds per acre. Worms. Several different types cause damage to Brussels sprouts. The most common are worms of the diamond-back moth (Plutella maculipennis) , loopers {Trichoplusia spp.), the imported cab- bage worm (Pieris rapae) , and cutworms (family Noctuidae). The caterpillars of the diamond-back moth are about % inch long and yellow-green, and they wriggle nervously when disturbed. They feed not only on leaves but on the sprouts them- selves. Looper larvae are green with a thin white line on either side and a line down the back. They are characteristically humped-back at rest or while moving. The imported cabbage worm is a velvety green caterpillar about one inch long that feeds on the foliage. The commonest cut- worm on sprouts is the variegated or black cutworm (Peridroma margaritosa) . This worm is 1% inches long when ma- ture, black, and has characteristic dia- mond-shaped markings down the back. All of the worms are satisfactorily con- trolled with a combination dust contain- ing 2 per cent parathion and 5 per cent DDT. Cabbage maggot. Small white mag- gots of the cabbage maggot {Hylemya brassicae) tunnel into the roots and underground parts of the plants. Infesta- tions first occur in the seedbeds, but the transplants in the field may be attacked. The damage retards growth or may even kill the plants. Control in the seedbed consists of dusting the surface of the soil with a 5 per cent chlordane dust at the rate of 100 pounds per acre, which is raked into the upper 1% to 2 inches of soil before planting. When the plants emerge, apply a 5 per cent chlordane dust at 14-day intervals concentrating 50 pounds per acre along the rows. Dusting the roots and stems of trans- plants with a 5 per cent chlordane dust gives some protection from later maggot attacks in the field. Some growers prefer to dip the roots and stems in a chlordane solution. Use 4 to 5 ounces of a 40 per cent chlordane wettable powder or 3% to 5 fluid ounces of a 50 per cent emulsion per 10 gallons of water. Slugs and snails. The gray garden slug (Deroceras reticulatum) is the most destructive on Brussels sprouts. It is about % to 1 inch long, gray, and lacking a [9] Left: Damage to roots of Brussels sprouts by cabbage maggot; plant on left Is undamaged. Right: Damage to seed by seedpod weevil; pods on left are normal, those on right show 100 per cent loss. shell. The greenhouse slug (Milax gaga- tes) is 1 to 1% inches long, dark gray, with a keel down the back. The European brown snail (Helix aspersa) often dam- ages sprouts along the edges of fields. Control is obtained with arsenic-metalde- hyde baits in pelleted form, applied broadcast at the rate of 20 to 40 pounds per acre. Several applications are often necessary. Thrips. The onion thrips (Thrips tabaci) is very injurious to sprouts. Thrips feed on the undersides of the leaves causing them to dry and become red. They enter the sprouts and cause swellings, and in addition are difficult to remove by washing. Either a 2 per cent parathion dust or a 5 per cent DDT dust applied at the rate of 40 to 50 pounds per acre will give good control. Seedpod weevil. This small weevil (Ceutorhynchus assimilis) is a new pest of the seed crop, and unless adequate control is practiced losses of 25 to 30 per cent may occur. A 1 per cent crude benzene-hexachloride dust or a 1 per cent lindane dust used at the rate of 40 to 50 pounds per acre gives good control. Dust- ings should start when the flowers first appear and should be continued at 14-day intervals until the pods are well devel- oped. From four to eight dustings are necessary because of the constant move- ment of weevils from native mustard host plants. Gophers. Pocket gophers commonly infest Brussels sprouts fields, where they cause damage by burrowing under the plants and cutting roots. Gopher popula- tions often build up more in sprinkler- Damage caused by slugs (left) on leaves, and (right) on heads. irrigated fields than where furrow irriga- tion is used. Some growers use furrow irrigation early in the season to drive gophers to the edges of the fields. Trap- ping and poisoning by baits are com- monly used for control measures. Details on control are given in California Exten- sion Circular No. 138. Field mice. The white-footed mouse and the meadow mouse have caused dam- age in plantings located in canyons where brush surrounds the fields. They climb up on the plant and feed on the center head and sprouts. Control measures are outlined in the Circular listed under gophers, above. Nematodes. Certain species of nema- todes are known to attack members of the cabbage family. Brussels sprouts will probably be attacked when grown in the warmer areas on soil infested with root-knot nematode {Meloidogyne spp.) . The sugar-beet nematode {Heterodera schachtii) has also been found on crops of this group in the coastal areas where the crops have followed sugar beets. In- vestigational work being carried on at present may prove that other species of nematodes are also important pests of Brussels sprouts. Plant diseases Clubroot is caused by a soil-borne fungus, Plasmodiophora brassicae. Af- fected plants are stunted and have swollen and distorted roots. These plants wilt readily on hot days. Recently clubroot has been spread to many farms in the Half Moon Bay area. Once the soil is infected the disease will remain for many years. Clubroot can be introduced into clean fields by infected plants, by in- fected soil such as on farm equipment, and by surface waters. Extreme caution is necessary to prevent the introduction of this disease into clean fields. Do not use infected areas for seed- beds, and do not obtain plants from dis- tricts where clubroot is known to exist. In fields already infected good control RESIDUES AND HAZARDS Be careful in handling and applying chemicals suggested in this circular. Parathion and other phosphates are very poisonous to man and animals. Follow accurately the manufacturer's directions on the label. Do not apply insecticides such as DDT, lindane, and chlordane to plants within 30 days of harvest. New regulations allow the use of parathion to within 15 days of harvest on Brussels sprouts in San Mateo and Santa Cruz counties. has been obtained in experimental tests by using mercuric chloride at 1-2,000 in the transplanting water. About % pint of the solution applied at planting time gives control until late in the season. Ma- chine transplanters with water tanks will Adult of the cabbage seedpod weevil. The actual length of these weevils is about one- eighth of an inch. [ii] Examples of clubroot on Brussels sprouts plants; plant on the right is healthy. have to be used to apply the mercuric chloride solution. Blackleg, Phoma lingam, is a soil- borne fungus causing serious losses in some years. Affected plants are stunted, lower leaves often become red, the roots are rotted, and the plant may fall over in the field. A black area in the wood is seen if the underground stem is cut. Young plants in the seedbeds may show a small, dry, rotted area on the stem around the ground line. Warm soil favors this disease. In other regions, blackleg disease is carried on the seed, but this is not the case in California. Locating seedbeds every year on new ground or on ground that for several years has not been planted to sprouts or other cabbage crops is suggested. Plant- ing following a hot spell while the soil is still fairly warm favors the development of the disease in the field. Root rot is caused by any one of sev- eral fungi such as Phytophthora spp. and Pythium spp. which are favored by over- watering and poor drainage. When in- fected plants are pulled from the soil, the root system and part of the lower stem slips off. It is best to avoid poorly drained soils for planting. On some soils drainage ditches, mole balling, or subsoiling may help water penetration and drainage. White blight, caused by the fungus Sclerotinia sclerotium, produces a cot- tony, white fungus growth on the head and leaves. Small, black, hard bodies called sclerotia are found with the cot- tony fungus. White blight is particularly bad late in the season during wet weather. The sclerotia when worked into soil serve [12] to keep the fungus alive from year to year. No practical control is known. Fusarium and Verticillium wilts. These two wilt diseases are caused by two soil-borne fungi, Fusarium oxysporum f. conglutinans, and Verticillium albo- atrum. Either fungus, or both, may enter the roots and grow upward inside the plant causing yellowing, dwarfing, wilt- ing, and sometimes death. When the stem is cut open, brown to black streaks indi- cate the presence of the fungi. The wilt diseases show up most prominently dur- ing periods of warm weather. The only control at present consists in preventing infection by avoiding infected soils for both seedbeds and field plantings. Rhizoctonia, Wire stem, is a dis- ease caused by Rhizoctonia solani and is most severe in seedbeds where af- fected plants are stunted and sometimes reddish. The stem is shrunken and pinched — hence the name "wire stem." Control it by discarding all plants showing decay or wire stem at trans- planting time. On other crops good con- trol of Rhizoctonia has been obtained with an Arasan drench, applied to seed- beds with a watering can. Two applica- tions 10 days apart should give adequate control. The 50 per cent powder of Arasan is used at 1 to 1% pounds per 25 gallons of water. Botrytis rot or "slime" is caused by an air-borne fungus, Botrytis cinerea. Many times the entire head rots, and the sprouts slime and decay. This fungus is secondary and usually attacks only leaves that have been injured mechanically or by aphids and other insects. Some serious losses have been observed in fields where leaves and the central head were injured by insecticidal dusts. No practical chemical control is known at present. Keeping aphids from develop- ing in the center head by dusting on schedule may help. Be careful not to ap- ply too much dust by hand duster to the center head. Ring spot. Black spots, often showing a ring pattern, appear on the foliage and sprouts. This is a cool, wet-weather dis- ease. When very numerous, the spots run together and cause a black, scorched con- dition, or blight. The fungus which causes the trouble, Mycosphaerella bras- sicicola, lives on the dead, infected leaves left on top of the ground. In rainy weather spores or "seeds" of the fungus are shot into the air from these dead leaves and spread by the wind. No control has been worked out, but crop rotation and sanita- tion would probably prevent much of the damage. If all the dead, infected leaves were destroyed or buried in the soil the fungus spores could not reach the healthy leaves. Downy mildew. Young plants in seedbeds are often attacked by the downy mildew fungus, Peronospora par- asitica. It is easily recognized by the yellowish areas and the white mildew growth on the underside of the leaves. In severe attacks seedlings may be seriously delayed and even killed. Downy mildew is not generally serious in the field. The disease may be controlled by dust- ing seedbeds with a 5 to 8 per cent Par- zate or Dithane Z-78 dust at 35 to 45 pounds per acre. Spraying with a solu- tion containing Parzate or Dithane Z-78 wettable powders at 1% to 2 pounds per 100 gallons of water should also be suc- cessful. It will be necessary to dust or spray once every seven days until the trouble is corrected. A spreader-sticker must be added to sprays because sprout leaves are difficult to wet. Seedbeds with widely spaced rows are bothered less with downy mildew, be- cause the plants can dry quickly. When plants are closely bunched in rows, thin- ning out some of the weaker plants may give better aeration around the remain- ing plants. Black spot. Although this leaf-spot disease closely resembles ring spot, it is caused by one or more species of Alter- [13 naria. The spots are usually covered with black or brown mold growth, which consists of spores of the fungus. These spores or "seeds" are splashed from leaf to leaf during wet weather and cause new spots. The fungus may infect seed pods and in this way get on the seed. Seedlings started from diseased seed show a dark, shrunken stem, resembling wire stem, and are usually stunted. Spores that develop on diseased seedlings spread to the leaves of near-by plants, and in this way the dis- ease is carried to the field on transplants. Avoid using seed from infected seed plants. The fungus may also be present on diseased crop refuse left on the land — another reason for selecting clean land for the seedbed. Mosaic and other virus diseases occa- sionally occur on Brussels sprouts but seldom cause losses. They result in mot- tling or yellowing, distortion, and stunt- ing. These diseases are spread by insects, especially aphids. HARVESTING and HANDLING Sprouts form in the axils of the leaves starting with the lowest. They should be picked after they reach full size and be- come fairly firm but before they become tough or yellow. The first sprouts are ready in 3 to 3% months after planting; hence harvest usually starts in the earliest fields midway in August. At the first pick- ing the sprouts are normally of rather poor quality, and much of the work con- sists of cleaning off the large, soft Harvesting Brussels sprouts from a mature plant during January. Only one or two more pickings remain on this plant. sprouts from the plants. These are known as "faloppi," of which only a small per- centage is usually marketable. First pull off the leaves below the ma- ture sprouts, and then remove the sprouts by twisting them from the stem. Sprouts are picked into hampers or baskets, which are then emptied into burlap sacks for immediate hauling to the packing shed. Pickings are made at intervals of 2 to 4 weeks, depending on growing con- ditions. The heaviest production of good-qual- ity sprouts is obtained from the third to the sixth picking. Harvesting can be con- tinued as long as good sprouts are formed — usually from 20 to 22 weeks. The har- vest season may be terminated by heavy rains, disease or insect conditions, cold weather, or unseasonably warm weather. A seasonal total of about 160 hours of labor is required to harvest an acre. Yield The average yield is around 4.0 tons per acre, 4% to 5 tons being considered good. Occasionally during seasons fa- vorable to an extended picking season, yields of 6 to 8 tons have been obtained on the best soils. Marketing Being a highly perishable product, sprouts should be marketed promptly while maintained at as low a temperature as possible. Ideal conditions for main- [14] taining high quality are temperatures of 32° to 34°F and a relative humidity of 90 to 95 per cent. The part of the crop that is marketed fresh is shipped to all parts of the United States. Most out-of-state shipments origi- nate in Santa Cruz and Monterey coun- ties. The Los Angeles market is supplied largely from San Luis Obispo, Santa Cruz, and Monterey counties, while San Mateo County supplies much of the com- modity for the Bay markets. Preparation for fresh market. Sprouts must be cleaned and trimmed of loose leaves and sorted to remove soft, large, or damaged sprouts. This may be done in growers' sheds or in cooperative packing houses. The sprouts are usually prepared by hand while spread out on sorting tables. Some growers have a machine with a large, rotating cylinder similar to an almond huller, which removes the loose leaves and sorts out oversized sprouts. Damaged and otherwise low-quality sprouts can be removed from a moving belt, which carries sprouts from cleaner to packer. The 25-pound drum is the main con- tainer used for eastern shipment. The lettuce crate and the standard carrot crate holding about 80 pounds are the prin- cipal containers for local markets. In the San Luis Obispo district the apple or artichoke box holding about 40 pounds is also used for local market. Sprouts for prepackaging are cleaned and sorted in growers' sheds and then trucked to a special packing shed. They may be precooled by holding under re- frigeration at 32° to 34°F for several hours. The product is trimmed and re- sorted by women and then run through a cold-water bath (34 to 40°F). Blowers take off loose leaves and excess moisture. The sprouts move on conveyor belts into the packaging machines, where they are placed in cellophane bags. Net weight of the packaged sprouts is approximately 12 ounces. They are then placed in boxes of a dozen packages each for trucking to local markets. Packaging operations for fresh sprouts. The finished product, in a cellophane bag, with label attached, is similar to the one shown on the front cover. [15] Precool sprouts for eastern shipment by carrying them on a conveyor belt through a cold-water spray for 8 to 10 minutes. Put from 12 to 16 pounds of ice into the drum with the sprouts. Without precooling, more ice will be needed. Both top icing and bunker icing are used in the refrigerator cars during shipment. Sprouts for local market are seldom iced, though precooling and perhaps package- icing would be desirable during warm weather. To prepare sprouts for freezing. Sprouts for freezers are sold either field- run or after sorting and cleaning. Some large operators sell field-run rather than go to the expense of hiring additional labor for cleaning. Cleaned and sorted sprouts generally bring about 1 cent more per pound than field-run. Sprouts are trucked to the freezers in field crates or cannery lug boxes. The freezer industry demands excep- tionally good quality and low insect counts. For this reason the control of insect pests has become of major impor- tance in the production of sprouts for freezing. Aphids are the most serious pest because they get inside the sprouts and cannot be washed out. Deliver the crop to the freezer as rapidly as possible. If sprouts must be hauled some distance, put crushed ice in the containers. Seed production Growers produce most of their own seed. Make individual plant selections from the commercial fields during the winter. Dig these plants, and replant in a convenient spot. Protect them from wind and birds. Split the sprouts and the center head with a knife to permit seed stalks to emerge. Pods are well developed in July, and the seed is threshed by hand. The cabbage seed-pod weevil causes severe losses to seed plantings and must be controlled (see Pest Control, page 9) . Four good plants will produce about 1 pound of seed. In order that the information in our publications may be more intelligible it is sometimes necessary to use trade names of products or equipment rather than complicated descriptive or chemical identi- fications. In so doing it is unavoidable in some cases that similar products which are on the market under other trade names may not be cited. No endorsement of named products is intended nor is criticism implied of similar products which are not mentioned. Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, University of California, and United States Department of Agrieultnre 114. J, Earl Coke, Director, California Agricultural Extension Service. 10m-4,'33(A5633)A.A.