White spots on Chinese cabbage leaves that look scorched? Control methods for Cercospora leaf spot

    Cercospora leaf spot mainly damages Chinese cabbage leaves. When the disease occurs, many grayish-white, nearly round spots grow on the leaf surface, with 1-2 irregular concentric rings in the center and a pale yellow halo around the outside. On the underside of the leaf, the outer edge of the spot is dark green, but sometimes this is not obvious. The spots finally turn white and semi-transparent, as if scorched by fire. Sometimes the spots rupture or fall out. In the late stage of the disease, they merge into irregular large dead patches. When the air is humid, gray mold-like growth appears on the underside of the spots.

Cercospora leaf spot of Chinese cabbage

    Control methods:

    1. Choose disease-resistant Chinese cabbage varieties.

    2. Treat seeds properly: mix Chinese cabbage seeds with 75% chlorothalonil or 50% thiram wettable powder at an amount of 0.3-0.4% of seed weight; mix Chinese cabbage seeds with 50% iprodione wettable powder at an amount of 0.2-0.3% of seed weight.

    3. Strengthen cultivation management: in severely affected areas, practice a 2-3 year rotation with non-cruciferous vegetables. Level the land, increase basal fertilizer, sow at the right time, and prevent waterlogging in the field. After harvest, remove residual plants and fallen leaves from the field and plow them deep into the soil, which can reduce the pathogen, cultivate strong plants, and reduce disease occurrence.

    4. Chemical control: when scattered disease occurs in the field, spray with any one of the following pesticides: 50% carbendazim wettable powder 500-fold solution, 40% carbendazim suspension concentrate 800-fold solution, 75% thiophanate-methyl wettable powder 800-fold solution, 70% mancozeb wettable powder 500-fold solution. When downy mildew and Cercospora leaf spot occur at the same time on Chinese cabbage, mix 40% fosetyl-aluminum wettable powder 300-fold solution into the carbendazim solution. Spray about once every 10 days, for 2-3 consecutive sprays.