How to identify cucumber powdery mildew?

(1) dangerous symptoms. The main disease site is leaves, followed by petioles and stems, which generally do not harm fruits. In the early stage of the disease, small white spots will be produced on the leaves or back. When the environment is suitable, the spots expand and connect into one piece, forming a large white powder area with inconspicuous edges, and then expanding to the whole leaf. It is covered with white powdery mildew. In the late stage of the disease, many dark brown spots appeared on the diseased leaves, and the leaves turned yellow. In severe cases, the white powder turns gray, the leaves are yellow and curly, and generally do not fall off.

(2) Control technology. Comprehensive control measures were taken, which mainly focused on selecting disease-resistant varieties and strengthening cultivation management, combined with chemical control. Chemical control can be carried out by spraying 49% flusilazole EC with 8000 times solution at intervals of 2 days; Or spraying 900- 10% difenoconazole water dispersible granules every 7- 1500 days; Or spray 2500 times with 12.5% myclobutanil EC; Or spraying 4000 times of 50% azoxystrobin water dispersible granule solution at intervals of 65438+/-0 days; Or spraying 25% pyraclostrobin emulsifiable concentrate 2500 times at intervals of 65438 0 days; Or spray 75- 1% polyoxin aqueous solution; Or spray with 10% ningnanmycin soluble powder 1000 ~ 1500 times; Or spray 1% agricultural antibiotic wuyiencin aqueous solution 107 ~ 160 times.