Citrus shred leaf disease is a new citrus virus disease. According to the survey, the disease has existed in our country for a long time. It has occurred in Guangdong, Guangxi, Fujian, Zhejiang, Sichuan, Hubei and other provinces. The damage is serious. An important viral disease after the orange dragon disease, degenerative disease, and split skin disease.
The symptoms of citrus leaf breakage on Rusker oranges are: yellow transparent spots, round or irregular shape, leaf blade edge defects, leaf deformities, and leaf veins. The water-stained longitudinal grooves first appeared on the stems, then became yellowish-white streaks, slightly sunken, peeled off the bark at the macula, and there were no depressions in the xylem of the stems. Sometimes the streaks combined into patches and the branches bent. When severe, the plants dwarf. In citrus infected with leafy virus, fold yellow rings appeared at the grafting site and the base of the scions swelled. Above the ground yellow, deciduous. Plant growth is weak, dwarfing, results are few, and even dead. On the resistant and disease-resistant rootstocks are asymptomatic carriers.
The pathogen of citrus leaf shred is a kind of linear virus. Its size is 600-70015 nanometers. The lethal temperature of the virus is 65-70 degrees Celsius for 10 minutes. The virus is mainly transmitted through grafting, and Cuscuta can also spread. The grafting knife used for grafting is an important way to spread the virus. Citrus leaf virus did not find any insects. Long-distance transmission mainly depends on poisoned seedlings and scions.
The following countermeasures can be taken in the prevention and treatment of citrus leaf breaking disease:
1. Establish a disease-free nursery and cultivate disease-free seedlings
Selecting a healthy individual plant from the field and testing it with the indicator plant Rusker orange proves that the leafless virus can be used as a scion disease-free mother tree. In addition, healthy and excellent individual grafted seedlings can also be selected and treated with 30-44 degrees Celsius for 2 weeks. Then, 0.2 mm micro buds are cut at the growing point for shoot apex grafting to obtain propagation material without leaf virus.
2, using resistant, disease-resistant rootstock
Citrus leaf leaf virus mainly damages anthraquinone citrus. Avoid using quail as rootstock. The use of taro orange, sour orange, red tangerine, etc. as rootstock.
3, replacement stock
For young trees that are infected with leafy virus and appear yellow and grow weak, 2-3 resistant rootstocks can be used. After one year, the tree potential can be restored and a certain amount of production can be obtained.
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