When the leaves of grapes become Huang Shi, the overall growth will be weak. It may be caused by the lack of elements. If nutrients such as nitrogen, phosphorus and potassium cannot keep up, the leaves will turn yellow. Improper fertilization, fungal diseases and insect pests will also cause leaves to turn yellow, wither and fall off. In the process of growth, bad weather and rotten roots will gradually lead to yellowing of leaves in rainy days. Next, let's look at the lack of elements, diseases and other reasons.

1. Missing element

Potassium deficiency will cause bad spots on the edge of leaves, which look like burnt leaves. Branches and vines are also fragile and easy to break and shorten. Magnesium deficiency leads to yellowing between veins of old leaves, but has little effect on new leaves. Iron deficiency is the opposite, and the veins of new leaves gradually turn yellow, which has no effect on old leaves. Lack of nitrogen will cause the leaves to turn yellow-green, gradually turn yellow, gradually expand the yellow area, and the branches will be very thin. When zinc is deficient, the veins are very clear, but gradually turn green and yellow until necrosis.

2. Disease and fertilizer damage

Viral diseases can cause scattered yellow spots on leaves instead of continuous large areas of yellow. Fungal diseases can also cause yellowing of leaves and yellow spots, which are lighter than viral diseases. Improper fertilization will lead to root damage, and the leaves will gradually turn yellow and dry.

3. Other reasons

When the ph value of the soil is high, the iron in the soil will be converted into other compounds under alkaline conditions and cannot be absorbed by the roots of plants. Because the soil is alkaline, there is no way to absorb these nutrients in the soil even if fertilizer containing more iron is applied. Drought and high temperature environment, more water in rainy season will also lead to yellowing of grape leaves.