1. Planting management techniques
(1) Appropriate density
Select a high, flat, easy-to-drain, deep, fertile sandy loam plot, with deep furrows and high ridges. The ridge width is 120 cm, with 2 rows per ridge, and the hole spacing is about 25-30 cm. There are 2-3 plants per hole, and about 10,000 plants are planted per mu. Dig furrows in the ridges and apply base fertilizer deeply. Keep the field dry and water-free, and ventilated and light-permeable. Apply 75 kg of compound fertilizer or (2000-2500 kg of farmyard manure and 25 kg of compound fertilizer) per mu.
(2) Cultivate strong seedlings
Cowpeas are easy to germinate and generally do not need to be soaked for germination. The bottom soil of the seedling bed should be compacted, preferably 6 cm thick loam, to prevent the taproot from penetrating into the soil and growing multiple fibrous roots. This will cause serious damage to the root system when transplanting the seedlings. Therefore, when the seedlings have a pair of true leaves, they can be transplanted with soil. It is not suitable to transplant large seedlings. If conditions permit, seedlings can be grown in nutrient pots or plug trays, with two or three seedlings per pot.
Use insulated beds or nutrient pots for seedling cultivation, and disinfect the seedling facilities to prevent the seedlings from being infected. Transplant before the first compound leaf develops. Transplantation in nutrient pots can be delayed until the seedlings have 2-3 compound leaves. Transplantation should be done on sunny days.
When direct seeding is done, intertillage should be carried out every 7-10 days after the seedlings have emerged or after transplanting to loosen the soil and conserve moisture, and the seedlings should be allowed to grow to promote root growth. Intertillage should be stopped after the vines have stretched.
(3) Reasonable racking
When the plant sprouts vines, it is necessary to rack it. Use a herringbone rack or an X-shaped rack, 2-2.5 meters high, 10-15 cm away from the base of the plant, one pole in each hole, 15-20 cm deep, and when two racks intersect, place a horizontal pole at the intersection of 4/5 of the upper middle part and tie it tightly. Leading the vines to the rack is usually done at noon or in the afternoon on a sunny day. Do not do it when the dew has not dried or it is raining to avoid breaking the vines and leaves. Leading the vines should be done in a counterclockwise direction.
(4) Prevent excessive growth in the early stage and premature aging in the later stage
In the early stage of cowpea, it is not advisable to apply too much fertilizer to prevent excessive fertilizer and water from causing excessive growth. Generally, manure water is applied once after the plant is alive. After buds, flowers and harvest, fertilizer and water supply should be strengthened. Generally, topdressing is applied 2-3 times, and 750-1000 kg of human and animal feces and urine are applied per mu each time. If manure cannot be applied due to heavy rain, 5-10 kg of urea can be applied in the middle hole of the row spacing. In autumn, it is promoted all the way.
After the plants bloom and set pods, especially after the first batch of pods are harvested, more fertilizer and water should be applied. A total of 50 kg of 45% compound fertilizer and 4 kg of urea should be applied per mu, and fertilizer should be applied every 8-10 days to promote flowering, extend the harvest, and increase yield. For topdressing, the principle of thin application in the early stage and dense application during the flowering and setting pods should be followed. Note that after the first batch of pods are harvested, urea must be applied to increase nitrogen fertilizer, which has a greater impact on yield.
(5) Reasonable pruning
② Prune the vine waist. Most nodes above the first inflorescence have both flower buds and leaf buds. The characteristics of flower buds and leaf buds are: flower buds are hypertrophic, bracts are wrinkled and rough, two buds grow side by side, leaf buds are small and torch-shaped, and bracts are flat and smooth. During the seedling stage, the young leaf buds on each mixed node should be removed in time to promote the growth of flower buds. When the side branches grow out, one leaf can be left and pinched, and the first node of the side vine can be used to form inflorescences.
④ Main vine topping, when the main vine is 2.2-2.3 meters long, topping promotes the formation of secondary flower buds on each inflorescence and facilitates the harvesting of pods.
(6) Timely harvesting
After sowing, young pods can be harvested after about 60 or 40 days. After flowering, pods should be harvested in time when they are fully grown, tender and the seeds are just exposed after about 7-12 days.
2. Disease and pest control techniques
(1) Cowpea rust
Rust is a common disease on cowpeas. It often occurs in the middle and late stages of cowpea growth. It mainly harms the leaves. In severe cases, stems, petioles and pods can all be affected. In the early stage of the disease, small yellowish spots appear on the back of the leaves, which are slightly raised and then expand to form reddish-brown blisters. After the blisters rupture, reddish-brown powder is released. It is a very easy-to-identify disease.
①Agricultural control: Rotate with other non-leguminous crops for 2 to 3 years. Cultivate on high ridges, plant at reasonable density, dig ditches for drainage, and apply more phosphorus and potassium fertilizers to enhance plant growth and disease resistance. Prune branches in time, remove diseased and damaged plants in time after harvest, and take them out of the field for centralized destruction to reduce the source of bacteria in the field.
② Chemical control: Spray pesticides at the early stage of the disease, with an interval of 7 to 10 days between applications, and control 2 to 3 times in a row. The pesticides can be 40% flusilazole emulsifiable concentrate at 6000 to 8000 times dilution, or 10% difenoconazole water-dispersible granules at 1000 to 1500 times dilution, or 15% triadimefon wettable powder at 1000 times dilution, etc.
(2) Cowpea root rot
① Agricultural prevention and control: select early-maturing varieties, sow early at the right time, and plant in ridges; increase the application of phosphorus and potassium fertilizers, and the organic fertilizers must be fully decomposed; and implement 2-3 years of crop rotation with cabbage and onion and garlic vegetables.
② Chemical control: To prevent and control root rot, the soil must be disinfected first. Use 50-120kg of quicklime per mu of land combined with land preparation for application, or use 3-5kg of 70% soil fungus elimination wettable powder, add 50-100kg of fine soil, mix well, and evenly spread in the sowing hole, cover with a layer of fine soil, and then transplant or sow seeds. In the early stage of the disease, use 500 times of 70% methyl thiophanate and 300 times of 50% carbendazim to irrigate the roots.
(3) Cowpea blight
The disease mainly harms stems, leaves or pods. The disease occurs in stems, mostly near nodes, especially near the ground. In the early stage of the disease, the diseased part appears as water-soaked dark brown spots, which then spread around the stem and turn brown and constrict. The stems and leaves above the diseased part wilt and die. When the humidity is high, white mold grows on the surface of the diseased part. After the disease occurs, the leaves appear as nearly circular or irregular dark brown spots with sparse white mold on the surface.
①Agricultural prevention and control: Implement crop rotation for more than 2 years. Use ridge cultivation in low-lying wetlands, plant at a reasonable density, and drain water in time after rain. Burn the diseased branches in batches after harvesting.
② Chemical control: At the beginning of the disease, spray 200 times of 40% aluminum triethyl phosphate wettable powder, or 500 times of 70% ethyl manganese wettable powder, or 500 times of 58% metalaxyl. manganese zinc wettable powder, or 500 times of 64% chlorpyrifos wettable powder, or 800 times of 50% metalaxyl copper wettable powder, or 600 times of 72.2% purike water solution. Spray once every 10 days, for a total of 2 to 3 times.
(4) Cowpea wilt
Cowpea can be affected from seedlings to adult plants, and the disease is more severe during the flowering to pod-setting stage. When the disease occurs, it usually starts from the leaves closer to the ground from bottom to top. In the early stage, it wilts and droops at noon, and returns to normal in the morning and evening, as if it is dehydrated. Then it wilts and cannot recover, and finally the whole plant dies. The vascular tissue at the base of the stem and the root turns brown, and the root rots. When it is humid, a pink mold layer grows on the surface of the diseased part.
①Agricultural prevention and control: Rotate with non-leguminous crops for more than 3 years, and apply organic fertilizer that is not bacteria-carrying and fully decomposed for better results; mix seeds with 50% carbendazim wettable powder accounting for 0.5% of the seed weight, or soak seeds in 40% formaldehyde 300 times liquid for 4 hours, rinse with clean water after soaking and then sow.
②Chemical control: Spray urea, potassium dihydrogen phosphate, humic acid and other foliar fertilizers on the leaves to promote the vigorous growth of plants and improve their disease resistance; when the plants are sick, the most direct and effective method is to irrigate the roots. In the early stage of the disease, use 800 times of 70% thiophanate-methyl wettable powder, 500 times of 50% carbendazim wettable powder, 600-800 times of 70% dichlorodiphenyltrichloroethane wettable powder, or 500-600 times of 40% chlorpyrifos wettable powder, and irrigate once every 7-10 days, with 250 ml of liquid per plant.
(5) Coal mold disease of cowpea
It can occur from seedling stage to adult plant, and the disease is more serious in the middle and late growth stages, mainly harming leaves and causing leaf fall. Initially, red or purple spots appear on both sides of the leaves, which then expand into light brown nearly circular spots. The surface is densely covered with soot-like mold, with more on the back of the leaves than on the front. In severe cases, the diseased leaves dry up and fall off early.
②Chemical control: After the disease occurs, spray with 64% antimicrobial alum wettable powder 600 times liquid, or 25% carbendazim 400 times liquid, or 5% triadimefon 500~1000 times liquid, or 70% mancozeb wettable powder 600 times liquid; spray once every 10 days, and spray 2~3 times in a row.
(6) Cowpea virus disease
It is caused by infection with three viruses: cucumber mosaic virus, cowpea aphid mosaic virus and broad bean wilt virus. It is a common and serious disease in production. After the plant is infected, yellow-green spots appear on the leaves at first, and then the dark green parts gradually protrude and become warty. Leaf deformity is the most typical feature. Severely diseased plants grow slowly, are short, and have few flowers and pods.
The virus likes a high temperature and drought environment, and the suitable temperature range for development is 15-38 degree , because the virus usually invades through wounds. Therefore, when aphids occur heavily, it is easy for the disease to occur and spread.
①Agricultural prevention and control: Reasonable crop rotation, choose virus-free seeds, soak the seeds in clean water for 3-4 hours before sowing, and then soak them in 10% trisodium phosphate plus 800 times diluted new lipid film for 20-30 minutes; sow in appropriate amounts, and spray 800 times diluted new lipid film in time after sowing to keep warm and moist, prevent soil crusting, and improve seedling emergence rate.
② Chemical control: During the aphid outbreak, spray with 2000-3000 times diluted 10% imidacloprid wettable powder. When sporadic diseased plants are found in the field, spray with 500 times diluted 20% Virus A wettable powder or 1000 times diluted 1.5% Plant Disease Elixir emulsion.
