How to treat the latest strawberry powdery mildew?

Strawberry powdery mildew is a major disease in strawberry production. Strawberry powdery mildew can occur in the whole growing season of strawberries. Infection at the seedling stage results in a decline in the quality of seedlings, which is not easy to survive after transplanting. The quality of strawberries is seriously affected and the yield, quality and economic benefits of strawberries are seriously affected. Let's take a look at how to treat strawberry powdery mildew.

Symptoms of strawberry powdery mildew

Strawberry powdery mildew mainly harms leaves, petioles, flowers, pedicels and fruits, but rarely occurs on stolons. In the early stage of the disease, a thin white mycelium layer grew on the back of the leaf. With the aggravation of the disease, the leaf curled upward in the shape of a spoon and produced dark stains of different sizes. After that, the disease spot gradually expanded and a layer of thin frost-like white powder was produced on the back of the leaf. In severe cases, multiple disease spots were connected to the whole leaf. The buds and flowers are infected, the petals are pink, and the buds cannot open. When the fruit is infected, the young fruit can not expand normally and dry up.

The cause of strawberry powdery mildew

The main results are as follows: 1. Strawberry powdery mildew is a disease of low temperature and high humidity, the optimum temperature is 1525 ℃, the optimum temperature for conidia occurrence and infection is about 20 ℃, and the relative humidity is above 90%. If we encounter less sunshine such as continuous overcast, rain, fog and snow from late autumn to early spring, low temperature and high relative humidity are conducive to the continuous production of spores and repeated infection, resulting in the outbreak of the disease.

2. The incidence of strawberry in continuous cropping in greenhouse was early and serious, and the onset period of the disease was about 1 month earlier than that in the newly built greenhouse. The onset of the former is mostly in mid-October, while the latter does not appear until mid-November. Fertilization is closely related to the disease, partial application of nitrogen fertilizer, strawberry growth is exuberant, the leaf surface is large and tender green easy to suffer from powdery mildew. If the appropriate period, appropriate amount of nitrogen fertilizer, increase the application of phosphorus and potassium fertilizer, the disease will be lighter.

How to treat strawberry powdery mildew?

1. Use protective fungicides to prevent the disease twice before flowering, spray with 200 times of 2% Wuyisin water or 600 times of 75% chlorothalonil wettable powder once every 7 to 14 days, and the effect of alternate use of agents is better.

2. After the onset of the disease, drugs with protective and therapeutic effects should be selected for prevention and treatment. 3000 times of 50% ether carbendazim water dispersible granule or 1000 times of 4% tetraflurane water agent should be sprayed once every 7 to 10 days, and the effect of alternate use is better.

Prevention of strawberry powdery mildew

1. Select disease-resistant varieties and cultivate disease-free and strong seedlings.

2. Reasonable crop rotation to reduce the occurrence of diseases.

3. Remove old leaves, diseased leaves and residual leaves in time, and do a good job in field health management.

4. reasonable irrigation, control the humidity in the shed and reduce the disease.

5. Reasonably control the amount of nitrogen fertilizer and apply more phosphorus and potassium fertilizer.