How to control black spot of rape

First, the symptom of rape black spot mainly harms leaves, petioles, stems and pods. Leaves infected with primary brown round disease spot, slightly concentric wheel pattern, sometimes surrounded by yellow halo, when the humidity is high, black mildew. The disease at the junction of petiole, petiole and main stem forms oval to fusiform ring-shaped disease spots, which will lead to the death of lateral branches or the whole plant when they surround the lateral branches and the main stem for one week. 2. ⑴ selected disease-resistant varieties, such as "Yuyou 18", etc.; ⑵ carried out large-area rotation, advocated compost made by retting with enzyme bacteria, adopted formula fertilization technology, avoided partial and excessive application of nitrogen fertilizer, and paid attention to increasing potassium fertilizer; ⑶ seed treatment. Seed dressing with 50% thiram wettable powder of 0.4% seed weight or 0.2-0.3% 50% prohydantoin wettable powder At the initial stage of ⑷, spray 75% chlorothalonil wettable powder 600x solution, or 40% Dafudan or 80% Dasheng M45 WP 500x liquid, or 64% Dabu alum WP 500x solution, or 50% prohydantoin WP 1500 times solution, or 80PQ WP 800x solution, or spray 12% green copper EC 600x solution or 1Glug 150 times Bordeaux solution.