First, the incidence of symptoms of powdery mildew in strawberry generally occurs, especially in the protection of the incidence of heavier. The disease mainly damages the leaves, fruits and fruit stems of strawberries. At the beginning of the disease, a thin, creamy white powder appeared on the leaves and spread rapidly to the whole plant under appropriate conditions. As the disease progressed, the leaves curled upwards to form a spoon; after the flower buds and flowers were affected, the petals changed. In red, buds cannot be opened; if the fruit is infected with the disease, the fruit surface will cover a white powdery material, the fruit will stop hypertrophy, and the coloration will be poor.
Second, the incidence of the law of powdery mildew with mycelium or conidia in the sick overwintering over the summer, as the first source of infection. Bacteria belong to low-temperature pathogenic bacteria, infection temperature is 15-20 °C, less than 5 °C and higher than 35 °C are not pathogenic. Dry and high humidity conditions can cause disease spread. Pathogenic bacteria are mainly transmitted by air, and rainfall can inhibit spores from scattering, and they are scattered and scattered in the sunny afternoon. The disease is more serious in protected areas such as greenhouses. Partial application of nitrogen fertilizer in the field, due to the growth of tender, poor resistance to disease, the general incidence of heavier.
Third, the prevention and control methods 1. The use of disease-resistant varieties, such as Baozao Zaoxian. 2. Clearing the garden in winter, burning its diseased leaves and stubbles. 3. In the growing season, the old leaves and diseased leaves on the ground must be promptly removed and the diseased fruits should be removed. They should be deeply buried and should not be thrown away. Pay attention to the ventilation conditions in the garden, and drain it in time after the rain. In the application of fertilizers to increase organic fertilizer, phosphorus and potassium fertilizers, avoid partial nitrogen fertilizer. 4. Chemical control: (1) The right medicine. To use myclobutanil 800-1000 times solution, DuPont Fuxing 800-1000 times solution, thiophanate-methyl 1000 times solution, triadimefon 2000 times solution, and "Shigao" 600-800 times solution. (2) Proper control. To use the drug at the beginning of the disease, give it once every 7-10 days. (3) Improve the quality of prevention and control. Liquid medicine should be sprayed on the foliage and leaves, and alternately use various agents as far as possible. (4) To master the safety interval, use drugs to stop the use of drugs 7 days before harvest to control pesticide residues.
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