Leaf surface greenish yellow spots, high humidity when the back of the leaf with gray-white mold. Is downy mildew: high humidity is the main condition of the disease, temperature control, control of humidity, proper ventilation of the greenhouse to reduce humidity can effectively reduce and mitigate the occurrence of downy mildew.

Frosty mildew as far as possible before the onset of drug prevention, or in the early stages of the onset of drug prevention and control.

Preventive and curative agents: Fenitrothion hydrochloride, Fenitrothion cyanide, Manganese zinc, Allylmorph. Manganese zinc, allylmorpholine, flumioxazin. Fenpyroximate, mefenoxam, manganese zinc. Flumethrin, Kite (enoyl. Pyraclostrobin) or Degin (20% allyl.27% azoxystrobin). Combined with potassium dihydrogen phosphate spray. 7 days once, used 2 to 3 times in a row