Control methods of powdery mildew of zucchini

Powdery mildew is the main disease of zucchini, which occurs all over the country. it occurs most commonly in spring and autumn, with an incidence of 30,100%, which has a significant impact on yield. generally, the yield is reduced by about 10%, and when it is serious, it can be reduced by more than 50%. Besides harming zucchini, it also harms cucumber, pumpkin, wax gourd, towel gourd, melon and other melon crops. Let's take a look at the prevention and control methods of zucchini powdery mildew.

Harmful symptoms

Zucchini can be infected from seedling stage to harvest stage, mainly harmful to leaves, followed by petiole and stem, followed by fruit. At the initial stage of the disease, white powdery small round spots were produced, and then gradually expanded into irregular white powdery mildew spots (that is, conidia of pathogens). The diseased spots can be connected into pieces, and some of the damaged leaves gradually turn yellow. in the later stage, many small yellowish-brown particles were produced on the disease spot (that is, the ascomycetes of the bacteria). When it is serious, the diseased leaves turn brown and die, and the powdery mildew turns to gray.

Morbidity regularity

The pathogen of zucchini powdery mildew overwinters in the soil with the remains of the disease, or in protected areas. The pathogen in southern vegetable area overwintered and oversummer with hyphae or conidia on the host, and spread by airflow, Rain Water and watering. The disease could occur at 10 to 25 ℃, and the disease developed rapidly with the alternation of high temperature, dryness and humidity. In the later stage of growth, the disease of plant growth is serious. The disease is also serious because of overdense planting and lack of fertilizer during the growing period.

Prevention and cure method

1. Prevention at seedling stage: using chlorothalonil, carbendazim or methyl thiophanate to spray alternately once every 10 days, many kinds of diseases were prevented and the effect was good.

2. Ventilation and light transmission: timely removal of the old leaves, yellow leaves and diseased leaves in the lower part of the plant to increase its ventilation and light transmittance can greatly reduce the incidence of powdery mildew and increase the rate of flowering and fruit setting.

3. Chemical control: at the initial stage of the disease, tetrafluoroether azole + Zhantou + 100 fertilizer formula was evenly sprayed, or Xingnong 50% sulfur suspension 250 times + Zhantou + sea green formula. If the growth is too prosperous, Guanxin + Shigao + Zhantou + 100 fertilizer formula can be used to prevent and cure.