What causes abnormal winter leaf drop in citrus? How to prevent and control it

Citrus is one of the most common fruit trees in our lives. It is an evergreen fruit tree that rarely sheds leaves in autumn and winter. Once abnormal leaf drop occurs, it is bound to affect the yield and quality of the coming year. So what causes abnormal winter leaf drop in citrus? Let's take a look together with the editor.

I. Causes of abnormal winter leaf drop in citrus

1. Nutrient deficiency

When citrus lacks nitrogen, phosphorus, potassium and trace elements such as calcium and boron in winter, it can cause leaf yellowing and shedding. This is one of the main causes of citrus leaf drop.

2. Water imbalance

When the soil is too dry, the root growth of the plant is inhibited, and when the transpiration of the plant exceeds the absorption of the root system, the leaves will wilt and curl, and in severe cases the petioles will fall off. In addition, when water accumulates, the soil permeability is poor, which inhibits root respiration, and over time the roots will rot, which will also cause the aboveground branches and leaves to yellow and drop, and in severe cases the plant will die.

3. Poor light

The growth and development of leaves cannot do without photosynthesis. If the plant is too dense and the light is insufficient, the inner leaves will become larger and thinner, and the leaf color will be dull or even yellow. Winter light is inherently weak, and if it is not improved for a long time, a large number of inner branches will drop their leaves.

4. Pest and disease damage

During the citrus growing period, red spiders, scale insects, anthracnose and yellow spot disease all cause the greatest damage, and if not controlled in time, they will cause a large number of leaf drops in spring and winter.

5. Other reasons

In addition, pesticide damage, fertilizer damage, strong wind, freezing damage and girdling may all cause abnormal leaf drop in citrus.

II. Control measures

1. Strengthen tree vigor

In production, phosphorus and potassium fertilizers and organic fertilizers should be applied in combination with deep plowing, so that the root system grows deep, and foliar fertilizer should be sprayed, pruning should be reasonable, and drainage and irrigation should be timely, so as to cultivate strong tree vigor and improve the tree's resistance. For plants with pesticide damage, foliar fertilizer and brassin can be sprayed on the crown branches and leaves to alleviate it, while for leaf drop caused by improper girdling, foliar fertilizer should be sprayed in time or electrical tape should be used to seal the girdling wound, and within one month after girdling, avoid spraying pesticides such as lime sulfur mixture that easily cause leaf drop.

2. Do a good job in pest and disease control

Before overwintering, a comprehensive orchard cleaning should be done to reduce the base number of pests and diseases. Adding 2,4-D to the orchard cleaning is beneficial for preventing freezing and protecting leaves. For a large number of leaf drops caused by anthracnose and yellow spot disease, once found, they should be controlled in time to reduce the damage, and pesticides should be sprayed in time during the growing season to protect the leaves.

3. Pay attention to freeze prevention

In addition to measures such as planting in suitable sites, applying sufficient base fertilizer and whitewashing the trunks, in production attention should also be paid to spraying for citrus winter leaf drop after fruit harvest and before freezing; second, emergency freezing measures should be taken, and before frost, potassium dihydrogen phosphate solution should be sprayed in time to slow down tree thawing and restore leaf function.

4. Supplement nutrients

In production, attention should be paid to deficiency symptoms, and once found, they should be controlled in time, applying the right remedy, and applying whatever fertilizer is lacking.

  The above is an introduction to the causes of abnormal winter leaf drop in citrus and the control measures. We hope it can help you. To learn more related knowledge, please follow us.