Soybean gray spot disease mainly damages the adult plant leaves and can also infect the seedlings, stems, pods and seeds. Half-round or round-brown lesions appear on the cotyledons of diseased seedlings. The lesions on the leaves of adult plants were initially greenish round spots and gradually developed into frog eye-like spots with brown edges, central grays, or gray-brown eyes. It is also known as frog eye disease. Late forms of irregular lesions can also be formed. When wet, the central part of the lesion on the back of the leaf is densely coated with gray mold, which is the conidia of the pathogen. In severe cases, the lesions are covered with foliage, the lesions merge, and the leaves dies off. Stem-spotted spindle or elliptic, freckle round or oval, due to hairy, easy to see mold layer. The lesions on the grain are similar to the leaf spot, mostly round frog eyes.
Control methods:
1. In areas where the seedling stage is relatively humid and rainy, use 50% thiram or 50% carbendazim to seed, 0.3 kg per 100 kg of seeds;
2, for susceptible varieties, densely growing soybean fields, in the early stages of disease or pods and grains susceptible to spraying, in order to control the lesions on the grain. The commonly used agents are 40% carbendazim gel suspension or 50% carbendazim wettable powder, 100 grams per acre, 100% 50% thiophanate-methyl, and 80-100 kg watered. According to the development of the disease, interval 7 days to 10 days, a total of 2 to 3 times.
Control methods:
1. In areas where the seedling stage is relatively humid and rainy, use 50% thiram or 50% carbendazim to seed, 0.3 kg per 100 kg of seeds;
2, for susceptible varieties, densely growing soybean fields, in the early stages of disease or pods and grains susceptible to spraying, in order to control the lesions on the grain. The commonly used agents are 40% carbendazim gel suspension or 50% carbendazim wettable powder, 100 grams per acre, 100% 50% thiophanate-methyl, and 80-100 kg watered. According to the development of the disease, interval 7 days to 10 days, a total of 2 to 3 times.
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