Control of three soybean diseases

Soybean root rot: the disease can occur and cause damage throughout the growth period of soybean, with a yield reduction of 25% to 75% or more. The protein content of the damaged seeds decreased obviously, and the main symptom was that the dark brown disease spot appeared at the base of the stem and spread upward to the lower lateral branches, which made the pith of the diseased stem brown, the base of petiole constricted and the leaves drooping, but did not fall off. The main application of chemical control is 58% Ruidu Manganese Zinc or 72% Kelu wettable powder, the dosage is 0.3% 0.4% seed dressing. Soybean Sclerotinia sclerotiorum: soybean Sclerotinia sclerotiorum mainly infects the stem and begins to occur in late July. there are brown spots on the stems at the initial stage of infection, and then there are white cotton-like mycelium and white particles on the spot, and then turn black particles (sclerotia). In the longitudinal section of the stem of the diseased plant, the black cylindrical mouse fecal sclerotia could be seen, and the diseased plant was grayish white after death. Spray 50% sulfamethoxazole wettable powder 1000 times or 1000 times of Sclerotinia sclerotiorum or 50% methyl topiramate. Soybean gray spot: also known as spot disease, generally began to occur in the first and middle of June, and entered the peak period in mid-July. The disease of pods began from the tender pod stage, the grain filling stage was the peak stage, and the disease was serious in high temperature and rainy years from July to August. Mainly harmful leaves, when the disease is serious, almost all leaves are covered with disease spots, resulting in premature shedding of leaves, a yield reduction of 20% to 30%, and a decline in quality. Chemical control: in addition to sowing seeds with 70% dimethazone wettable powder or 50% thiram wettable powder according to 0.3% of the seed amount, 40% carbendazim glue suspension 1.5 kg per hectare was sprayed with 450 kg water.