Spring rapeseed sclerotinia stem rot control methods and technical key points

Rapeseed sclerotinia stem rot is a major disease harming rapeseed, and control must be taken seriously to reduce the damage and minimize losses.
Symptoms: When this disease occurs, the leaf lesions of rapeseed are round or irregular in shape, with the center grayish brown or yellowish brown, the middle dark bluish green, and the outer edge with a yellow halo. When dry, the lesions crack and perforate; under moist conditions, they expand rapidly, the whole leaf rots, and white mycelium grows on it. Stem lesions are spindle-shaped, slightly sunken, white in the middle, and brown at the edges. Under moist conditions, the lesions develop very rapidly, and white mycelium grows on them. In the late stage of the disease, the stem pith is eroded hollow, the cortex splits longitudinally, the vascular bundles are exposed, the roots break easily, and many black granular sclerotia form inside the stem. Severely affected plants die completely.
Control measures: Control can be carried out when more than 95% of main stems have flowered and about 50% of primary branches have flowered. It should be noted that the pathogen of rapeseed sclerotinia stem rot has generally developed resistance to carbendazim-type fungicides, so using single agents and their mixtures such as junsuijing, procymidone, shibaike, wanmeiling (diethofencarb), and dilituo (propiconazole) is more effective. Per mu, use 100-150 grams of 40% junsuijing wettable powder, or 35-50 grams of 50% procymidone (sumilex) wettable powder, mixed with water for spray control. Alternatively, per mu, use 40-50 milliliters of 25% shibaike, or 100 grams of 50% wanmeiling, or 25-30 milliliters of 25% dilituo, or 80-100 grams of 50% fu·junsuijing (thiram + junsuijing), etc., mixed with water for spray control. During the full flowering stage of rapeseed, remove the yellow leaves and old leaves from the middle and lower parts of the plants and all diseased leaves from the whole plant, and carry the removed leaves out of the field for disposal.