Prevention and treatment of citrus Huanglong disease without timely destruction of orchard

At present, Huanglong disease has occurred in a large number of oranges in southern China, which has seriously damaged citrus production, and many orange farmers are at a loss. Once Huanglong disease occurs, if the disease is not treated properly, the whole plant will be dug up and the whole garden will be destroyed. The experience of prevention and control of citrus Huanglong disease is introduced as follows.

Citrus Huanglong disease

First, the yellowing caused by water damage. Citrus roots are extremely intolerant to water. If soaked in water continuously for 48 hours, the capillary root (citrus nutrient root) will be moldy. Therefore, it is suitable for soil with a water content of 60-80%. In case of continuous rainy days, the roots are easy to lack oxygen when soaked in water, resulting in rotten roots. In particular, the citrus orchards cultivated without digging deep holes and high ridges are more likely to rot Rhizopus whiskers, resulting in yellow leaves. Therefore, the citrus orchard should be in the place where the groundwater level is low and the soil is loose and refreshing. During cultivation, it is required to dig deep holes and raise high ridges (higher than 40cm above the ground level). For citrus trees yellowed due to water damage after planting, we should do a good job of drainage around the garden, dig deep 40cm ring ditches at the dripping line outside the trees, put miscellaneous branches and leaves at the bottom of the ditches, add appropriate amount of grass and charcoal ash, and then cover the soil to make the roots have a lot of oxygen and organic matter, which is conducive to the restoration of tree momentum.

Second, yellowing caused by fertilizer damage. The roots of citrus trees, especially the capillary roots, are sensitive to high concentration of fertilizer. If the concentration of fertilizer is too high, the ammonia is too heavy, you will be burned. Therefore, when applying fertilizer, the fertilizer should be applied to the outer line of the branches and leaves of citrus trees as far as possible, and the farm manure which is not retted and mature can not be used. The rotten farm manure should also be drenched thinly. The concentration of chemical fertilizer should be 0.5-0.8. In summer, it is necessary to protect the root plate of citrus trees from exposure, and plant beneficial grass or cover grass in the orchard to improve the root activity of fruit trees.

Third, nutrient deficiency. Most chemical fertilizers (compound fertilizers) contain only three elements (that is, nitrogen, phosphorus, potassium, and some do not even contain potassium), while citrus trees need 12 elements such as calcium, magnesium, sulfur, zinc, manganese, iron, copper, boron and molybdenum. Such as long-term application of a single compound fertilizer, it will cause yellow leaves, withered branches and other diseases. Therefore, the fertilizer used for citrus trees should have comprehensive fertilizer effect and nutrition, such as chronic high-quality fertilizer, which should be retted with peanut bran, soybean bran, rapeseed bran and phosphate fertilizer, and the mixed application of fresh branches and leaves and grass should also be a good organic fertilizer. Quick-acting fertilizer, with more comprehensive nutrition is better, such as imported high potassium, calcium, boron fertilizer, Israel's nutritional potassium nitrate. These new concentrated compound fertilizers contain more than 8 elements and can meet all kinds of nutrients needed by citrus trees. Especially in autumn (September-October), citrus trees need the most nutrients in a year, such as lack of nutrition, it will lead to yellow leaves in winter, many abnormal flowers in spring, and a large number of fallen flowers when blooming, affecting the next annual yield.

Fourth, viral chlorosis (Huanglong disease). The characteristics of citrus trees with Huanglong disease are as follows: the leaf tip is small, hard, dull and yellowing, the veins are swollen, the new branches are short and clumpy, and there is no serous in the skin of the branches. At present, there is no specific cure for the disease, and it can only be prevented for a long time: introduction of ⑴: introduction of virus-free seedlings from scientific research institutions. ⑵ kills citrus planthopper and whitefly (planthopper is the medium that spreads Huanglong virus). Spray tetracycline hydrochloride 2-3 times in spring, summer and autumn (1.5-2.5 kg per tablet to water). ⑶ protects the roots of citrus trees, avoids water damage, fertilizer damage and lack of nutrient elements, and improves tree resistance. ⑷ found that citrus trees with Huanglong disease should be dug up and burned.