Main diseases of Welsh onion

Green onion purple spot disease 1, symptoms: damaging leaves and pedicels, the initial drought water stains white spots, and then become light brown network or spindle-shaped slightly sunken spots, continue to expand dry brown or dark purple, often surrounded by yellow halo, the disease is dark brown or black-gray with concentric wheel-like arrangement of mildew, the disease continues to expand, resulting in the whole leaf yellowing, withering or breaking. At the initial stage of the disease, spray 75% chlorothalonil, or 64% disinfectant alum, 40% Dafudan, 58% metalaxyl, manganese zinc wettable powder 15000 times, or 50% prohydantoin wettable powder 15000 times, once every 7-10 days, 3-4 times in a row. 2. Symptoms of green onion downy mildew: green onion downy mildew is mainly harmful to leaves and pedicels. Pedicel on the primary yellow-white or milky yellow larger infection spots, fusiform or oval, on which white mold is produced, and later becomes yellowish or dark purple. In the early stage of the disease, spraying 90% triethylphosphonate aluminum wettable powder 500 times liquid or 75% chlorothalonil wettable powder 600 times liquid, 50% nail cream copper wettable powder 800 times liquid, 64% poisonous alum wettable powder 500 times liquid, 72.2% Pulicol water agent 800 times liquid, 70% manganese wettable powder 500 times liquid, 60%, ethylphosphine aluminum wettable powder 500 times solution, once every 7-10 days, continuous prevention and treatment for 2-3 times. 3, onion, onion gray mold symptoms: the first white spots on the leaves, oval or nearly round, 1-3 mm in diameter, mountainous leaf tips developed downward, gradually connected into pieces, so that the onion leaves curled and withered. When the humidity is high, a lot of gray mold is produced on the withered leaves. At the initial stage of the disease, spraying 50% carbendazim 70% methyl thiophanate wettable powder 500x solution, you can choose. 50% carbendazim or. 50% propofol and 50% nonglide wettable powder 1000-1500 solution, or 80% carbendazim wettable powder solution has a good effect. 4. The symptoms of green onion rust are mainly damaged leaves, pedicels and green stems. In the early stage of the disease, oval slightly raised orange blister spots were produced on the epidermis, and the posterior epidermis ruptured and turned outward, spreading orange powder, that is, bacterial summer spores and summer spores. After autumn, the blister spot becomes dark brown, and when it breaks, it spreads dark brown powder, namely teliospore pile and teliospore. At the initial stage of the disease, 15% triadimefon wettable powder was sprayed with 2000-2500 times, or 50% triadimefon EC, 3000 times, 1000 times mancozeb wettable powder and 1.5% triadimefon wettable powder 2000 times, once every 10 days, for 2-3 times in a row. Symptoms of Welsh onion blight: green and white spots did not appear at the beginning of the disease of leaves and pedicels, and became gray and white spots after enlargement. causing the leaves to wither. When the rain is continuous or the humidity is high, the disease grows white cotton hairy mildew; when the weather is dry, the white mold disappears, and cotton-like white mycelium can be seen by tearing open the epidermis. The method of prevention and treatment was sprayed with 60% spray at the initial stage of the disease. Ethyl phosphine aluminum wettable powder 500 times liquid or 70% B. manganese wettable powder 500 times solution, 58% metalaxyl. Manganese zinc 500 times solution, 64% poison alum M8 wettable powder 500 times solution, 72. 2% Purek water agent 800 times liquid, once every 7-10 days, continuous prevention and treatment for 2-3 times. Insect status: onion fly, onion maggot occurrence regularity: onion fly produces 2-3 generations a year. They lay eggs on the green onions near the ground, or under the clods near the green onion plants. Onion flies like warmth and sunshine, but sooner or later they often lurk in the soil crevices. Onion fly larvae harm the white base of green onion roots, wither in light and die in heavy ones, resulting in lack of seedlings and broken ridges. Mainly in divination harm onion, stem disk and roots, causing the upper leaves to turn yellow and dry, with 40% methyl isophos emulsion 500 times solution 50% phoxim 400 times solution irrigation root, in the harm side trench irrigation drug seal. Onion thrips (Fig. 18) damage leaves, sucking white spots formed by mesophyll and, in severe cases, grayish-white due to chlorosis. The above two kinds of insect pests use internal inhaler 40% omethoate emulsion 800 times, spray 100 jin per mu, spray once every 7 days, spray 2-3 times continuously. Symptoms of soft rot of onions and onions: during the bulb expansion period in the field, translucent gray spots were produced in the lower part of 1-2 outer leaves, and the leaf sheath softened and rotted at the base, causing the outer leaves to fold and the disease spots expanded downward; the bulbs were water-immersed at the beginning, and then began to rot inside, giving off a stench. In the early stage of the disease, 50% copper succinate wettable powder was sprayed at the initial stage of the disease. Or 77% can kill particulate wettable powder 500x liquid, 14% complex ammonia copper water agent 300x liquid, 72% agricultural streptomycin sulfate soluble powder 4000 times solution, neophytomycin 4000-5000 times solution, depending on the disease once every 7-10 days, prevention and treatment once or twice. Symptoms of yellow dwarf disease of scallions and onions: the growth of diseased leaves is inhibited, the leaves are twisted and thinner, resulting in uneven leaf surface, leaf tips gradually yellowing, sometimes producing yellow-green mottled or yellow stripes of different length, onion tubes twisted, growth stagnant, waxiness reduced, leaf sagging yellowing, serious whole plant dwarfing or wilt. At the initial stage of the disease, 1.5% Zhiyanling emulsion was sprayed, or 20% virus A wettable powder 1000 times, 83 resistance enhancers 100 times, once or twice every 10 days. Symptoms of garlic leaf blight: mainly harmful leaves or pedicels. Most of the leaves are infected with the tip of the ten leaves or other parts of the leaves, showing small white dots of flowers at first, and irregular or oval gray-white or grayish-brown spots after enlargement, on which black mildew occurs, and in severe cases, the diseased leaves die. At the beginning of the disease, the prevention and treatment methods began to spray 75% chlorothalonil wettable powder 600x liquid, or 50% prohydantoin wettable powder 1500 times liquid, 64% alum wettable powder 500x solution, 50% succinic acid copper acid wettable powder 500x solution, 60% sodium dimethylidene. Ethyl phosphine aluminum wettable powder 500x liquid, 14% ammonia copper water solution 300x liquid, 1jade 100 Bordeaux solution, once every 7-10 days, continuous prevention and treatment for 3-4 times. Symptoms of Sclerotinia sclerotiorum disease of scallions and onions: mainly harmful leaves and pedicels, primary leaves or pedicel tip discoloration, gradually expanding downward, causing onion plants to die locally or completely, leaving only new leaves. Peel off the diseased leaves and produce white cotton floss-like aerial hyphae, small yellow-brown or black sclerotia scattered under the epidermis of the diseased part, with a size of 0.5-7 mm. Sulfur suspension 500x solution, or 50% methyl thiophanate wettable powder 400500x solution, 50% propofol wettable powder 100x 1500 fold solution, 50% nongliposide (ethinolide) wettable powder 1000 times 1000 times of methylisofos EC, once every 7-10 days, 2-3 times in a row. Symptoms of white rot of onions and onions: the leaves turn yellow from the top down and die, and the young plants usually wither. When the mature plants are weak, withered and humid a few weeks later, many fluffy discolored bacteria grow on onions and adventitious roots, and the hyphae recede to reveal black spherical sclerotia. The root or bulb is rotten in the field and is immersed in water. The bulb can continue to rot during storage. Control methods (1) 3-4 years rotation should be carried out, and continuous cropping should be avoided in diseased fields. (2) strengthen the field inspection, dig out the diseased plants and bury them in time. (3) before sowing, the seeds were mixed with 50% prohydantoin wettable powder with 0.3% seed weight. (4) about 5 weeks after sowing, the diseased field was sprayed with 50% carbendazim wettable powder 500x solution, or 50% thiophanate methyl wettable powder solution 1000-1500 times solution to irrigate the rhizome. The above fungicides can also be sprayed during the storage period, in which 50% of the hydantoin has a good wettability. In addition, it can also be sprayed with 1000 times of methylisofos EC, about once every 10 days, once or twice.