How to control downy mildew of rose

Downy mildew is a fungal infectious disease. Rose downy mildew is a destructive disease with rapid incidence and serious harm. It mainly harms the new branches and leaves in the middle and lower part of the plant. In the early stage, the lower leaves appeared on the back of the chlorosis spot, and the spot was irregular, and covered with frost-like mildew layer, in the later stage, it was dark purple, like water immersion, until it turned brown. The disease spot is polygonal and gradually turns into a burning shape. when the damage is serious, all the leaves fall off and the plant dies.

Prevention and control measures 1. Reasonable close planting, not more than 12 plants per square meter, at the same time, leaves should not shoulder to shoulder. two。 Reasonable fertilization, balanced nutrition, more application of organic fertilizer, under the premise of sufficient nitrogen fertilizer, enter the reproductive growth period to apply more phosphorus and potassium fertilizer to enhance plant resistance. 3. Clean up the residual branches and fallen leaves in time and destroy them centrally. Or spray 2000-fold solution of desenamine during dormancy to prevent the invasion of bacteria. 4. After the plant is susceptible to disease, metalaxyl, chlorothalonil and Kelu are used alternately. Usually spray once every 7 to 10 days, three or four times in a row.