What is the reason why grape leaves turn yellow?

What is the reason why grape leaves turn yellow? The yellowing of grape leaves may be the cause of iron deficiency.

The main manifestation of iron deficiency in grapes is that the young leaves lose their green color, and the leaves on diseased plants are yellow except the veins, while the old leaves are still green, which is a unique manifestation of iron deficiency. When iron deficiency is serious, the leaves appear milky white, or even turn brown to form leaf necrosis, and at this time, the inflorescence also turns pale yellow, the bud falls off, and the fruit setting rate is seriously reduced. Iron deficiency in grapes is closely related to soil pH and ventilation. When the ph value is too high (saline-alkali soil), the iron in the soil is often transformed into insoluble iron that the roots can't absorb and utilize (at this time, the soil analysis does not show iron deficiency, but the iron in the soil can't be utilized by plants), and a similar phenomenon will occur when the soil is too viscous and the irrigation water is alkaline. Therefore, the prevention and treatment of iron deficiency should supplement iron, improve soil and promote the transformation of iron in soil into usable state. Different varieties have different sensitivities to iron deficiency. Among them, Jufeng, Jingya, Tengnian and other European and American hybrid varieties are most sensitive to iron deficiency, and are prone to iron deficiency yellowing.

Prevention and treatment of iron deficiency: ① pay attention to the improvement of vineyard soil, increase the application of organic fertilizer, deepen cultivation to improve the soil, and prevent soil salinization and excessive adhesion. (2) Spraying 0.2% ferrous sulfate solution on the leaves, and spraying 1 time at 7 7- 10/day in the early growth stage for 3-4 times. In order to enhance the absorption of iron by grape leaves, a small amount of vinegar and 0.3% urea solution can be added when spraying ferrous sulfate, which has a good effect on promoting the absorption and utilization of iron by leaves and greening.

I hope you can adopt it. Thank you.

What is the reason why the leaves of Lagerstroemia indica turn yellow and have black spots? There are many reasons why Lagerstroemia indica leaves turn yellow and have black spots. First of all, you have to breed varieties with good traits, such as red plum and red plum, with stable traits.

Secondly, it may be that pests and diseases have occurred. Insect killing and sterilization, pay attention to insect prevention.

It may also be caused by lack of fertilizer.

Brown spot brown spot is also a common disease of garden plants, which often occurs in the growing season of Lagerstroemia indica. The occurrence of brown spot disease often leads to a large number of dead leaves and fallen leaves of plants. Affect viewing and flowering. 1, symptoms-Lagerstroemia indica is also a fungus, which mainly attacks leaves, usually the lower leaves begin to get sick, and then gradually spread to the upper parts. At the beginning of the disease, the lesions were round or nearly round, with different sizes and a few irregular shapes. The focus is purple-black to black with light edge color. Then the color of the lesion deepened, showing black or dark black, and the boundary with the healthy part was obvious. In the later stage, the color of the lesion center becomes pale and small gray-black mildew spots appear. When the condition is serious, the diseased spots become one piece, the whole leaves turn yellow quickly and fall off early. 2. Occurrence regularity-Lagerstroemia indica brown spot is caused by Cercospora rutaecarpa infection. The pathogen overwinters on the diseased residue in the form of mycelium or conidia, and then carries out primary infection and reinfection through conidia in the following year, and spreads through airflow or wind and rain. Brown spot disease in Tianshui area generally begins in early summer and is seriously harmful in autumn. It is easy to break out in hot and rainy seasons, especially in years or seasons with frequent rainstorms; Generally speaking, the lower leaves are more susceptible to infection than the upper leaves. Control method: 1. Early detection of horticultural control, timely removal of diseased branches and leaves, centralized incineration or deep burial, and reduction of pathogen sources. Strengthen cultivation management, plastic pruning, so that plants are ventilated and transparent. It is best to change the soil for family potted plants every year. 2. At the initial stage of chemical control, 500 times of 50% carbendazim wettable powder, 65% zineb wettable powder 1000 times or 800 times of 75% chlorothalonil wettable powder can be sprayed for control.

What is the reason why the grape leaves suddenly turn yellow after continuous rain? In rainy season, poor soil drainage, too wet soil and poor air permeability will all cause partial root system death of grapes, leading to root system weakness. When grapes suddenly encounter high temperature and strong light, the leaves are not transpiration enough, which causes heat damage and the leaves of grapes turn yellow.

What is the reason why the stems on the grape leaves turn yellow? It is caused by a virus strain that produces pigment. At first, it turns yellow along the main vein of the leaf, and then it extends to the inter-row area, and the leaf is slightly deformed and becomes smaller.

What are the reasons why the leaves of vines turn yellow and fall off during the fruit-dropping period, and how to prevent them? There are pests, or the leaves are too dense. You can try microbial fertilizer. The brand "Zhu Youbao" is ok, and it is said that the effect is good.

What is the reason why the leaves of Bodhi tree turn yellow and dry? Are you sick? Typical leaf spot is also one of the main diseases of bodhi trees, which is caused by high ambient temperature and poor ventilation. It is necessary to spray 800 times of methyl acetate and mancozeb in time for prevention and control, strengthen tree management, remove dead leaves, cool down and ventilate, and cooperate with spraying humic acid foliar fertilizer to enhance plant resistance.

What is the reason why the potted cypress leaves turn dry and yellow? What else does Rong have to learn? It is more difficult.

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