Control techniques of citrus yellow leaf disease

Citrus yellow leaf disease, also known as Huanglong disease, yellow tip disease, yellow blight, green fruit disease, etc., is a devastating disease in citrus production in the world, caused by a gram-negative bacteria limited to the phloem. It can infect many kinds of Rutaceae plants, including Citrus, Fructus Aurantii, Golden Citrus and Jiuli incense. Let's take a look at the control techniques of citrus yellow leaf disease.

Symptoms of citrus yellow leaf disease

1. Mottled yellowing: after turning green, the mottled yellowing leaves fade locally and form mottled yellowing, the mottled position and shape are very irregular, foggy, and there is no clear boundary. Most of the mottled leaves originate from the veins, base or edges of the leaves.

2. Uniform yellowing: uniform yellowing often occurs after the local temperature drop in autumn, and the new leaves do not turn green in late autumn, and gradually form uniform yellowing, mostly in the periphery of the crown, toward the sun and at the top.

3. Element deficiency etiolation: element deficiency etiolation is not a real element deficiency, but is caused by local root rot caused by Huanglong disease, resulting in a decrease in fertilizer absorption capacity and leaf element deficiency, which is mainly similar to the symptoms of zinc deficiency and manganese deficiency, which is an auxiliary symptom for the identification of Huanglong disease.

Incidence conditions of citrus yellow leaf disease

1. There is a disease source in orchard or near orchard, that is, yellow leaf disease tree.

2. There is a virus vector in or near the orchard, that is, citrus planthopper.

3. Citrus planthopper can be infected after feeding on diseased trees for a total of 5 hours.

4. Irregularity occurs in the orchard, and tender shoots occur at any time, which can attract citrus planthopper to feed and transmit virus.

Control techniques of citrus yellow leaf disease

1. Strict quarantine system to prevent the introduction of diseased seedlings and ears into disease-free areas and new planting areas.

2. Cultivate disease-free seedlings.

The ① nursery should choose to be in a disease-free area or a place with good isolation conditions, or use a plastic net shed to raise seedlings.

The citrus virus-free breeding system was established by ②. All selected improved varieties must be tested by indicator plants or polymerase chain reaction (PCR). The stem tip seedlings were obtained by stem tip grafting virus-free technique, and the disease-free seedlings were propagated according to the virus-free procedure.

When the ③ "system" was not established, the seeds of rootstocks should be collected from the fruits of disease-free trees. The seeds were soaked in 50-52 ℃ hot water for 5 minutes, preheated and then soaked in 55-56 ℃ hot water at a constant temperature of 50 minutes. The scion should be collected from the identified disease-free mother tree and soaked in 1000 times tetracycline hydrochloride solution for 2 hours, then rinsed and grafted with clean water.

④ strengthens the management system of nursery.

3. Control citrus planthopper

① strengthens cultivation management, neatly sprouting new shoots each time, and unified spraying control. Pesticides should be sprayed for the first time in the budding period to prevent adults from laying eggs in the bud gap. Organophosphorus is the main pesticide, and isocarbophos, omethoate or oil emulsion can be selected.

It is the key to control citrus planthopper in the whole year that ② strengthens garden cleaning and spraying in winter to eliminate citrus planthopper with poor activity during overwintering.

③ adjusts the variety structure of fruit trees, does not plant Rutaceae plants such as yellow bark and Jiuli incense in citrus producing areas, and prevents citrus wood lice from transferring hosts.

4. give priority to prevention and comprehensive prevention. Adhere to the comprehensive examination of Huanglong diseased plants after each new shoot turned green, and found that one plant was dug up and no residual piles were left. At present, the use of physical and biological comprehensive methods, including the use of low-temperature plasma compound preparation, has a good effect in prevention and control.

5. In order to rebuild the citrus orchard in the disease area, we should dig out the disease and old trees, clean up the environment, plant short-term crops for one year before planting citrus, or we can use isolation planting.

6. to develop citrus production in the way of industrial management, to achieve unified planning of development scale, unified varieties in the park, unified measures in production, unified guidance in technology and unified regulations in management. It can effectively control the incidence.

7. Three-dimensional prevention and control

① growth period (time) three-dimensional control, flower bud stage and leaf expansion stage is easy to be infected in the key period, the traditional Chinese medicine Vofengsu has the characteristics of high safety, at this time, the appropriate high concentration plays an important role in the disease control of the whole growing period. Autumn fruit harvest is the key period for pathogen breeding and hiding, which plays an important role in solving the number of pathogens and the degree of disease damage in the coming year.

Three-dimensional control of different parts (space) of ② plant. Kuifuling, a Chinese herbal medicine, has the characteristics of good conductivity. The roots, bark, leaves and fruits of the tree can absorb the effective components of the liquid, and can kill latent (phloem and overwintering) bacteria in the process of transmission.

③ usage of three-dimensional prevention and treatment, Chinese (herbal) medicine has the characteristics of nutritional rejuvenation, through rejuvenation to improve immunity and sterilization to control diseases, while root irrigation, clear garden (branch spray) and spray are the two three-dimensional ways to achieve the two effects.

8. The combination of Chinese and Western medicine: Chinese (herbal) medicine preparation has the advantages of compound composition, regulating growth, improving crop immunity, sterilizing broad spectrum, long effective period, preventing and treating diseases from inside to outside. the conventional use of single component has the characteristics of quick effect (high drug resistance), and the combination and compound use of Chinese and western medicine is beneficial to complement each other and ensure the effect in critical treatment.