1、 Disease manifestation
Powdery mildew, also known as white disease, mainly endangers the leaves of cucumber, followed by petiole and stem, but will not endanger the fruit. At the beginning of the disease, there will be white round pink spots on the front and back of the leaves, and then it will become a large white powder area, which will eventually cover the whole leaf. After wiping off the white powder, you will find that the leaves become withered and yellow and brittle. If the situation is serious, the leaves will turn gray and the whole leaf will wither. This disease will affect the photosynthesis of leaves, interfere with metabolism, and thus inhibit the growth of plants.
2、 Cause of disease
There are many possibilities of cucumber powdery mildew. For example, if the planting density is too high and the ventilation and light transmission of plants are not good, it is easy to breed fungi. The lack of soil viscosity may also lead to the reduction of plant disease resistance. In addition, if the fertilizer applied is not fully decomposed, it will also lead to disease. Growing in places with warm and dry climate and insufficient light, or long-term drying after continuous rain, it is also easy to get sick.
3、 Treatment method
In the early stage of the disease, you can mix kaize dry suspension, cuibei dry suspension, Shigao water dispersible granule, Luying EC and other agents into a solution for spraying. It is mainly sprayed on the diseased parts. Generally, it is sprayed once every 7 days, and it can be cured by spraying 2-3 times continuously. In addition to these agents, fumigation treatment can also be carried out with chlorothalonil or a fumigant, usually in the evening.
4、 How to prevent
If you want to prevent it, you must first choose a good variety. Some disease-resistant varieties have strong resistance to this disease. In addition, we should also control the planting density, do a good job in drainage, regularly check and remove the old and diseased leaves, pay attention to strengthening light transmission and ventilation, and properly supplement phosphorus and potassium fertilizer, which can also provide disease resistance.