First of all, symptoms
Diseases of tree trunks often occur where the sun shines. In the early stage, the phloem of the root was brown and sunken, and gradually turned black or even burnt, and the diseased skin cracked and tilted in the middle and late stage. On the fruit, the pinholes are different in size at first, and the dents are dark brown and small. With the aggravation of the disease, the lesions gradually expanded and dents gradually increased. If it is naturally ventilated and dried, the damaged part of the fruit surface is dry, the dent is dry and the color is dark brown; If the natural environment is wet and cold, the damaged part of the fruit is easy to rot, accompanied by juice overflow. Leaf damage mainly shows that some or all leaves turn dark brown and wither;
Second, the characteristics of concurrency
1, onset period
Fruits often change color in the mature stage, and most loquat fruit planting areas are from mid-May to mid-June. From June to September, under the high temperature and strong light, the branches and leaves suffered more.
2. Parallel standards
(1) species maturity. For example, the mature big five-star is easy to get sunburned by the sun, while the medium and early-maturing big species and release clocks are not easy to get sunburned by the sun.
(2) Fruit type. Generally 1 batch of fruit is easy to get sunburned, but 2 or 3 batches of fruit are not easy; Large fruits and discolored fruits are easy to get sunburned, while small fruits and dense fruits are not easy.
(3) Everywhere. Fruits in the sunny, upper and outer parts of the trunk are vulnerable, while fruits in the inner, lower and rear parts are not vulnerable.
(4) tree potential. The artificial forest has good fertilization and water management methods, effective plastic and cosmetic pruning, appropriate fruit retention, strong trees and many spring shoots, and those who cover fruits with leaves are slightly injured; Extensive management methods, weak trees, few spring shoots, and fruit-exposed people are seriously affected.
(5) temperature. When the temperature changes slightly and the precipitation is evenly distributed during the discoloration and ripening of loquat fruit, the occurrence of sunburn is relatively light or does not occur; If you encounter ultra-low temperature and rainy weather in the mature stage of color change, and then suddenly encounter high temperature and strong sunshine, your condition will be more serious.
(6) plastic surgery. After fruit picking, the plastic surgery is unscientific, and the opening angle is very large, which leads to the large gap between the trunks, and the sunbathers are easy to get sunburned; Plastic and cosmetic pruning is effective, trunk branches can be seen everywhere, and it is not easy to get sunburned.
Third, the way of prevention.
1, choose the appropriate one. When planting new varieties and replacing excellent varieties, resistant varieties should be selected according to local climatic conditions to prevent them from encountering high temperature, strong light and bad weather at the mature stage of discoloration.
2. Improve field management methods and increase tree potential. Improve subsoiling soil, apply more organic fertilizer, and use nitrogen, phosphorus and potassium together to make the soil layer fertile and loose, with good water and fertilizer conservation, thus promoting the vigorous growth and development of trunk and improving its stress resistance.
3. Scientific research bears fruitful results. Comb the fruit immediately and leave the fruit properly, so that the spring shoots are early, numerous, neat and strong, which is beneficial to avoid sunburn of the leaf cover fruit.
4. Effective integer adjustment. After fruit picking or high grafting, scientific research on plastic and cosmetic pruning will make the trunk branches evenly distributed, the concave-convex indoor space suitable and the branches not exposed.
5. Fruit and fruit bagging. In the middle and late April, after the fruit is combed for the second time or before the fruit changes color, it is bagged with loquat or made into paper bags.
6. Avoid high temperature. When the weather is hot, you can water the plantation continuously, hang trees on the surface of the trunk or shade it with wet wheat straw to cool down.