What Causes Litchi Fruit Cracking? A Full Guide to Prevention and Control

Litchi is sweet in taste and warm in nature, and has the effects of nourishing the brain and strengthening the body, stimulating the appetite and benefiting the spleen, and promoting appetite. However, fruit cracking often occurs during cultivation, bringing economic losses to fruit growers, so what is litchi fruit cracking? What to do? How to prevent it?

1. Causes of litchi fruit cracking

Litchi fruit cracking mostly occurs in the young fruit stage and before the fruit ripens, and cracking at maturity is the most serious, having the greatest impact on yield. The causes of litchi fruit cracking are many-sided; the structure of the fruit, the environmental conditions during the fruit development period, damage by pests and diseases, and cultivation and management conditions all have varying degrees of influence. According to several years of research and observation, the main causes of fruit cracking are:

1. Differences among varieties, such as Nuomici, Tianyan, Guiwei and others, which are cracking-prone varieties, while Huaizhi, Heiye, Feizixiao and other varieties crack less.

2. Abnormally high accumulated temperature during peel development, which shortens the peel development time, leaving the peel development inherently deficient.

3. Unbalanced nutrient supply to the plant in the early stage of fruit development; the nitrogen and calcium content in the leaves and the ratio of nitrogen to potassium content in the fruit are significantly related to the degree of fruit cracking. When the nitrogen and calcium content in the leaves is relatively high and the nitrogen-to-potassium ratio in the fruit is small, fruit cracking is relatively reduced; in addition, the calcium and boron content in the peel is also related to fruit cracking, and if insufficient, it will cause fruit cracking.

4. Uneven soil moisture supply and excessively low atmospheric humidity; when the fruit enters the rapid growth stage of the aril (flesh), if there is a long drought followed by sudden rain or typhoon rain, it often causes the atmospheric pressure to drop and humidity to increase, the transpiration capacity of the leaves to decline, and the osmotic potential of the flesh to decrease, causing the flesh to grow rapidly and exceed what the peel can bear.

5. Damage by pests and diseases, especially damage by downy blight and anthracnose, is one of the important causes of fruit cracking.

6. Improper cultivation and management, including unreasonable measures such as fertilization, irrigation and drainage, which worsen the soil environment and cause fruit cracking.

2. Symptoms of litchi fruit cracking

Litchi fruiting generally shows as the peel splitting open and the flesh being exposed. This situation is not only seen on a single fruit or a single tree; at least it affects several trees, and at most an entire mu. It is generally large-scale fruit cracking. Fruit cracking causes the fruit to drop. After dropping, because there are fewer fruits, the litchi tree will transmit more water and nutrients to the other fruits. In this way it enters a cyclical stage until all the fruits on the tree have dropped. If the drop is due to pests and diseases, the cracked fruits should be dealt with as soon as possible to prevent transmission to other fruit trees.

3. Main measures to prevent fruit cracking

1. Maintain a balanced water supply during the fruit development period: during the fruit development period, when the weather is dry, in addition to irrigation, the canopy also needs to be sprayed with water so that the fruit can grow under stable environmental conditions.

2. Provide a balanced supply of the nutrients needed during the fruit development period: in addition to a balanced supply of the three major elements nitrogen, phosphorus and potassium (N:P:K about 1:0.5:1), it is also necessary to promptly supplement calcium, boron, copper and other elements that are closely related to fruit development. Or apply more organic fertilizer during flower spike development and the young fruit stage.

3. In the middle and late stages of fruit development, adopt measures such as root cutting and girdling, which can weaken the vitality of the root system (its ability to absorb fertilizer and water) and has a relatively significant effect on reducing fruit cracking.

4. Pest and disease control: especially fruits infected by downy blight and anthracnose are prone to peel cracking; therefore, pest and disease control must be carried out well during the flower spike stage and the fruit development period.

5. Use chemical agents to prevent fruit cracking: 10 days, 20 days and 30 days after the female flowers fade, spray once each time with “litchi-specific anti-cracking agent” or “compound cytokinin”, for a total of 2 to 3 sprays; spraying 2 to 3 times in the middle and late stages of fruit development has a significant effect on disease prevention and cracking prevention.,