Control of three diseases of onion and garlic

First, purple spot. It is mainly harmful to chives, scallions, garlic, onions, leeks and so on. It is the main disease of scallions and garlic, and leaves and pedicels are the main damaged parts. The disease spot is watery at first, grayish white, slightly sunken, and then expanded into an oval or fusiform, purplish brown. When the humidity is high, the disease produces a black mildew layer arranged in the shape of a concentric wheel. When the disease is serious, it causes the leaves and stems to wither or collapse. The disease occurs seriously under warm and humid conditions or lack of fertilizer and drought. The disease is serious in sandy soil, dry land and fields seriously damaged by thrips.

⑴ agricultural control: apply sufficient base fertilizer, increase phosphorus and potassium fertilizer, strengthen field management, and implement crop rotation with non-onion crops. ⑵ seed treatment: soak the seeds with 40% formalin 300x solution for 3 hours before sowing, wash and dry before sowing. The bulbs can be soaked in warm water for 40-45 ℃ for 1.5 hours. ⑶ chemical control: at the initial stage of the disease, spray 70% mancozeb wettable powder 600x liquid, or 75% chlorothalonil + 70% topiramate wettable powder (1:1) 1000-1500 times liquid, or 64% poisonous alum 500x liquid, or 50% Baogong EC 1200 times liquid, spray once every 7-10 days, a total of 2-3 times. Pay attention to alternate use and mixed use.

Second, virus. Garlic and garlic are the most common virus diseases in onion and garlic. After the disease of garlic and onion, yellow and green stripes appeared, the diseased plants were dwarfed, the leaves shrunk and twisted, the bulbs became smaller and stiff, and the tillers decreased, which affected the yield and quality. Viral diseases are mainly transmitted by aphids. The disease is serious in general, such as high temperature and drought, extensive management, large number of aphids, partial application of nitrogen fertilizer, lack of fertilizer, poor plant growth and so on.

⑴ agricultural prevention and control: clean the countryside and reduce the source of poison. Sowing at the right time, strengthen fertilizer and water management, re-apply organic fertilizer, use more compound fertilizer or phosphorus and potassium fertilizer, and avoid partial application of nitrogen fertilizer. Remove and burn the diseased plant in time. Physical control of ⑵: silver gray film is used to avoid aphids, and a silver gray film 3-6 cm wide is hung every 60-100cm above the seedbed, which has the effect of avoiding aphids and preventing aphids. Set up yellow board to trap aphids. Oil on the yellow board is inserted in the field (about 60 cm high) to trap and kill winged aphids. ⑶ medicament prevention and cure: spray 1.5% Qianhongling emulsion 1000 times, or 1.5% virus A wettable powder 1000 times, or 20% virus A wettable powder 1000 times, or 83 antiviral agent 100x, or antiviral agent 1, once every 7-10 days. It was sprayed 2-3 times.

Third, bacterial soft rot. Garlic, onion and onion are the most common bacterial soft rot of onion and garlic. After the garlic is infected, it usually starts from the leaf edge or midrib of the foot leaves to form yellow-white stripes, which can run through the whole leaves. When the temperature is high, the diseased part is yellowish brown and soft rot, and then gradually extends to the upper leaves, causing the whole plant to wither and yellow.

⑴ agricultural control: rational crop rotation. Strengthen fertilizer and water management, apply sufficient base fertilizer, implement formula fertilization; high border planting in low-lying land, timely elimination of stagnant water; pay attention to field hygiene. ⑵ medicament prevention and cure: spray medicine in time at the initial stage of the disease, spray and shower are combined. 23% ammonia copper solution can be used for root irrigation, or 72% agricultural streptomycin 4000-fold solution, or neophytomycin 4000-fold solution, or 77% copper hydroxide (can kill wet powder) 400,500x solution can be used alternately for 3-4 times.