Color difference of Strawberry and Leaf cloth Powder Prevention and treatment of Strawberry powdery mildew in greenhouse

Powdery mildew is an important disease of strawberry in greenhouse, mainly damaging leaves, flowers, fruits and fruit stems, petioles will also suffer. At the initial stage of leaf damage, white powder grows on the back of the leaf. With the aggravation of the disease, the whole leaf is covered with white powder, the leaf edge rolls up, and the leaf gradually turns yellow; the flower bud is damaged, the petals are purple, and they do not normally open or cannot open; the strawberry fruit surface is covered with white powder, colored, and the young fruit stops expanding, loses luster and hardens.

strawberry powdery mildew

The occurrence factors of strawberry powdery mildew: (1) climatic factors. The disease is of low temperature and high humidity type. The optimum temperature for onset is 15~25℃, and it does not occur when it is lower than 5℃ or higher than 30℃. The lowest humidity was 40%. The higher the humidity, the more serious the disease. From late autumn to early spring, in case of continuous rainy days, low temperature and low light, humidity is high, conidia of pathogens are continuously produced and repeatedly infected, which is easy to cause disease epidemic. (2) Variety factor. The disease degree of different strawberry varieties was different, Mingbao and Yixiang were more resistant, Fengxiang was susceptible. (3) Cultural factors. Continuous cropping greenhouse disease early, serious disease; partial application of nitrogen fertilizer, strawberry growth tender green, poor disease resistance, serious disease.

Agricultural control: (1) Select disease-resistant strawberry varieties according to local conditions. (2) Rice rotation can be used in the field with powdery mildew disease. (3) Clean the countryside. After strawberry harvest, timely clean up and burn the sick and disabled bodies; before planting, remove weeds in the field; during the growth period, timely remove the diseased leaves, diseased fruits and old leaves, take them out of the shed, and burn them in a centralized manner. (4) Strengthen cultivation management. Cultivate strong seedlings and transplant them in due time; ensure proper plant spacing and reasonable dense planting; ventilate in due time, drain water in time after rain, reduce field humidity; apply fertilizer reasonably, take decomposed organic fertilizer and phosphorus and potassium fertilizer as base fertilizer, apply appropriate amount of nitrogen, phosphorus and potassium compound fertilizer during growth period, and do not apply nitrogen fertilizer partially; water scientifically, pay attention to water management after bud emergence, fruit expansion period and harvest peak period, and it is best to use drip irrigation under film instead of flood irrigation.

Chemical control: in the early stage of disease, timely application of drugs, with Shigao 10% difenoconazole water dispersible granules 1000~1500 times, or 12.5% myclobutanil EC 1500~2000 times, or 75% chlorothalonil wettable powder 600 times spray, once 7~10 days, continuous control 2~3 times. Spray evenly and thoughtfully, both sides should be sprayed. In case of continuous overcast and rainy days, chlorothalonil smoke agent should be used to reduce humidity in the shed. Do not use drugs during flowering to prevent phytotoxicity. Strictly implement the pesticide safety interval, generally stop using 7 days before strawberry harvest to control pesticide residues.