1. Mango physiological leaf blight is a physiological disease, which is related to malnutrition, poor root activity, poor environmental conservation and poor management.
2. It may also be malnutrition. The potassium content of diseased leaves is higher than that of healthy trees, and there is excess potassium ion, which leads to leaf edge burns.
3. Root activity and the surrounding environment, dry climate, high soil temperature, moisture can not keep up with the season or microclimate with high salt concentration, directly affect root activity. When there is proper precipitation and rhizosphere conditions are improved, plants gradually return to normal.
4. There may be pests. The black and withered bud is caused by mango transverse tail moth and leaf cherry mosquito, or it may be mango anthracnose, which is a common disease of mango. Spodoptera striata is a moth-eater. If it is invisible, the leaf cherry mosquito is even smaller and invisible. The pathogen of mango anthracnose mainly overwinters in infected leaves, branches, dead branches and weeds under fruit trees. When the temperature rises and the humidity increases, anthracnose will produce a large number of conidia, which can penetrate from the wounds of tender leaves and buds, bark cracks and cuticles of mango trees through wind and rain. The pathogen of anthrax has rapid infection ability, strong explosive force and strong survival rate. Every year, when the temperature reaches 20-30℃ and the humidity is high, it breaks out in the tender bud stage, flowering stage and young fruit stage of mango. At this time, the treatment method is spraying, using wanling powder and dichlorvos. After mixing in proportion, be sure to mix thoroughly and evenly.
The symptoms of mango seedling leaf blight are as follows: 1-3 When new shoots of young trees appear, brown wavy spots with water stains appear on the tip or leaf edge, which spread transversely to the midvein and the leaf edge gradually dries up. In the late stage, the leaves on the diseased branches gradually fall off, leaving bare branches, which generally do not die. The new shoots can still grow in the second year, but the growth potential is poor, the root color is slightly dark and the root hair is less.