Citrus rot disease is a disease that occurs in citrus producing areas and can easily cause large economic losses to citrus growers. Moreover, the disease has been easily mistaken for brown spot disease or anthrax disease prevention and control, so the control effect is not good. This article summarizes the symptoms, occurrence regularity and prevention and treatment measures of citrus rot disease for your reference.

Symptoms, occurrence regularity and prevention and treatment measures of citrus rot disease

1, symptom performance

After many years of observation, it is found that the disease mainly harms the citrus leaves and often causes a lot of fallen leaves. In the early stage of the disease, the surface of the leaves produced reddish-brown spots, which gradually expanded into a nearly round reddish-brown lesion. The central part of the lesion gradually changed to white, and the edge of the lesion on the back of the leaf had a yellow halo. In the late stage, the lesions in the center of the leaf are densely dark brown hairy small dots, arranged in a wheel pattern. In severe cases, multiple lesions are combined into large spots, and the diseased leaves are easy to fall off.

2, the law of occurrence

2.1 Mainly harmful to the middle and lower parts of the canopy

Generally, the mature spring shoot leaves are seriously damaged; the summer and autumn shoots are relatively lightly damaged. Symptoms began to appear in mid-December and gradually increased. The peak of the disease occurred from late February to mid-March, and the diseased leaves basically fell in the middle and late March.

2.2 Hazard is closely related to low temperature

According to the survey, the disease is the most serious in the late winter and early spring, and the high temperature season generally does not occur. In the years when cold damage occurs, it is easy to cause the disease to occur. At the same time, from late February to early March, if there is more precipitation, it will easily aggravate the infection and harm of the disease.

2.3 The degree of hazard of different varieties is different

According to the survey, the main citrus varieties in Chenggu County are generally susceptible to infection and damage to the citrus varieties such as rock sugar orange, local early, Nanfeng tangerine, and ponkan, while 'Xingjin' and 'Guanchuan ', 'Ninan No. 1', 'Dapu' and other early-maturing and early-maturing Wenzhou mandarin oranges are relatively mild.

2.4 The severity of the disease is related to the age of the tree

According to the survey, in the various industrial areas of the Chenggu test site in Chenggu County, the occurrence of large trees or old trees over 20 years old is common; young trees and young trees rarely occur.

2.5 related to planting density

The disease occurs in citrus gardens with large planting density, poor ventilation and light transmission, and closed trees.

2.6 related to cultivation level

Where the cultivation management is poor, as well as the low-lying and stagnant water, the fruit hangs for a long time, the fertilizer application is insufficient, and the citrus tree is weak, and the incidence is heavy.

Symptoms, occurrence regularity and prevention and treatment measures of citrus rot disease

3. Prevention and control technical measures

3.1 Strengthening cultivation management and cultivating robust trees

According to many years of observation, citrus rot disease is a weak parasitic pathogen similar to anthrax, and it only occurs when the citrus tree is weak. Therefore, it is necessary to pay attention to the implementation of technical measures such as scientific pruning, formula fertilization, disease prevention and control, drought and flood control, and timely harvesting, in order to cultivate a robust citrus tree body and improve the disease resistance of the tree. The fundamental measure of disease.

3.2 Pay attention to the orchard clearing garden and reduce the source of the disease

Before the germination of citrus spring shoots, combine the spring pruning to cut off the diseased diseased leaves, collect and burn, and reduce the source of the initial infection of the bacteria. After trimming, spray 4 times 45% (w) stone sulfur mixture crystal 150 times to enhance the clearing effect.

3.3 Scientific pruning, reasonable thinning

In the pruning, the "transparent shear" is implemented to open the "sunroof" to make the tree canopy in a good ventilation and light transmission state; if the planting density is too large, the phenomenon of canopy closure should be adopted. Change thin."

3.4 Do a good job in chemical prevention and control to prevent bacterial infection

The prevention and treatment of chemical agents should be based on prevention. The protective fungicides can be sprayed 1-2 times in the canopy of the middle and late August and the middle and late November to prevent the infection of the bacteria. In the Orange Park, where the disease is relatively heavy, the spring shoots are sprayed 1-2 times in the middle and late March or mid-April to protect the spring shoots.

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