Control of Botrytis cinerea in growing soybean

Botrytis cinerea is a common disease of soybean. when it is serious, it will wither the leaves, cause defoliation and reduce yield.

1) symptom: Botrytis cinerea can occur in the whole growth period of soybean. It mainly harms soybean leaves. The lesion is round to oval or irregular in shape, up to 2 cm in diameter. At the seedling stage, it first expanded from the edge of the leaf to the center of the leaf, forming a "V" shaped disease spot, which was light green at first, and then turned light gray to light brown, with a narrow dark brown or purple band on the edge. A large number of black, needle-sized spots are produced on the old disease spot, that is, the germ-dividing embracing device. Pathogens sometimes spread from leaves to petioles, stems and pods. Disease spots on petioles and stems striate, grayish or light brown, margin brown. The disease spot on the pod is round and the edge is red.

2) pathogen: Botrytis cinerea is caused by fungi. The meristematic embracing apparatus of the pathogen was buried in the leaf tissue, and then broke through the epidermis, scattered or aggregated, spherical, membranous, brown, 64-170 microns in diameter, with openings; the meristematic clasps were long oval or oval, and the single cell was colorless.

3) Control methods: resistant varieties were selected for ①. ② seed treatment. Mix seeds with 50% Fumishuang wettable powder or 70% dimethazone wettable powder with 0.3% seed amount. ③ soybean was used to remove the diseased plant residues in the field in time after harvest. Rotation with Gramineae crops for more than 3 years.