Prevention and treatment of citrus chlorosis

Citrus chlorosis is common in citrus orchards in many parts of our province, resulting in tree weakness, yield decline, quality degradation and premature senescence. Some fruit growers think that it is Huanglong disease and adopt the practice of cutting down trees, resulting in unnecessary production losses. In fact, as long as chlorosis is not caused by Huanglong disease, it can be revived through scientific management.

The main symptoms of citrus yellowing are root rot, rare new roots, yellowing of aboveground autumn shoots, smaller leaves, withered shoots, small deformed fruit and sour skin. The disease of mandarin is more serious than that of orange, mandarin and pomelo.

Citrus chlorosis is caused by physiological disorders and pests. The main physiological obstacle factors are poor site conditions, inappropriate fertilization, lack of organic fertilizer, reuse of herbicides, premature senescence of Fructus Aurantii rootstock, disastrous climate, lack of trace elements, unpruned trees, drought and water removal, etc. The main diseases and insect pests are Huanglong disease, anthrax, foot rot, root nematode, branch pests, split skin disease, broken leaf disease, resin disease, decline disease and so on.

Chlorosis caused by physiological disorders can be corrected by "four reforms", namely, land reform, fertilizer reform, tree reform and garden reform. Do a good job of expanding holes to improve soil, increase the application of organic fertilizer, apply more farm manure, pay attention to balanced fertilization, spray trace elements and other work to improve the content of soil organic matter, in order to provide sufficient nutrients for orange trees. Pay attention to the sprouting, tip control, heart picking and pruning of orange trees, cut off overgrown branches, shade branches, weak branches, disease and insect branches, dead branches, make the tree show a natural and happy shape, and adopt the methods of pulling branches and twisting branches to dwarf the "open skylight" of the tree, which is beneficial to ventilation and light transmission. Improve the infrastructure in the garden and improve the drainage and irrigation system to ensure the harvest of orange orchards by drought and waterlogging.

The occurrence of chlorosis caused by diseases and insect pests should be controlled by strengthening comprehensive pest control measures. Only when Huanglong disease is diagnosed by experts, drugs should be prescribed for different diseases, such as anthrax, 600 times of anthrax, 200 times of copper solution after scraping off the diseased part of foot rot, furrows of root nematodes can be applied with furrows of carbofuran 1 and 2 per plant, and branch pests can be cured by "scraping, wiping, painting, plugging, spraying".