Control of Gray Leaf spot of Soybean

Grey leaf spot is common in all soybean producing areas in China, but it is the most serious in Northeast China, all parts of the plant will be damaged, the damaged soybean seeds will become smaller and the oil content will decrease.

Main symptoms: the disease spot was formed after the plant and some pods were infected, and the disease spot of the adult leaf was round, oval or irregular, mostly grayish brown, gray or reddish brown, dark brown around the disease spot, and the boundary between the disease spot and healthy tissue was obvious. The disease spot on the stem is round or spindle-shaped, gray, and the margin is dark brown. Disease spots can also be formed on pods, seed coats and cotyledons.

The disease is a fungal disease, which overwinters with conidia or mycelium on diseased seeds or diseased plants. after diseased seeds grow out of seedlings, disease spots are formed on cotyledons to produce conidia, which spread with wind and rain and harm all parts of adult plants. In the northeast, the disease generally occurred in the first and middle of June and entered the peak period in mid-July, with high temperature, high humidity and heavy rain, and the disease occurred seriously. In August and September, when there were more Rain Water, the seed-carrying rate was high.

Control methods: first, select disease-resistant varieties; second, select soybean seeds produced in uninfected fields; third, chemical control. 50% carbendazim wettable powder plus 50% thiram wettable powder (3:2) can be used, and the total amount of medicine is 0.5% of the seed weight. Seed dressing After the seedling stage, 40% methomyl glue suspension 100ml per mu can be used, and 50% carbendazim wettable powder or 50% methyl thiophanate wettable powder can be sprayed with 100g water.