Treatment of tomato powdery mildew

Tomato powdery mildew: The disease occurs on leaves, petioles, stems and fruits. Infected with leaves, the leaves appear to fade green dots at the beginning, and then expand into irregular-shaped powder spots with white floc on the surface, which are hyphae, conidiophores and conidia of the pathogen. At first, the mildew layer is sparse, gradually increasing in a felt shape, and the lesions are enlarged or covered with whole leaves. Sometimes, the pink spot can also occur on the back of the leaf, and the front side is a yellow-green plaque with an inconspicuous edge. When the petiole, stem and fruit are infected, the surface of the diseased part also produces white powdery mildew.
Characteristics of the disease: The bacteria are overwintered in the field with the closed capsule and the diseased body, and the winter is mainly wintering on the tomato. When the conditions are appropriate in the second year, the ascospores scattered by the closed capsule are spread by the airflow, and the host disease department produces conidia and then repeatedly invades through the airflow. Where tomatoes are grown all the year round, there is no obvious wintering of the bacteria. The suitable temperature for the development of pathogens is 15-30.
Prevention and treatment methods: (1) Clean up the diseased body and remove the diseased body in time to reduce the bacterial source. Concentrate deep or burn.
(2) early onset optional pesticide WP 50% carbendazim 600-800 times, 15% of triadimefon (triadimefon) WP 1000 times. Spray once every 7-10 days, continuous control 2 to 3 times. The above agents can be used in turn to prevent the resistance of the bacteria.