Winter jujube is mainly infected with disease symptoms and regular prevention and control measures

Winter jujube is mainly infected with disease symptoms and regular prevention and control measures

Winter jujube is a relatively good economic forest tree species in recent years, the country's existing area of 50,000 hectares, in recent years, with the continuous expansion of jujube planting area and climate changes, the occurrence and harm of winter jujube tree diseases showed a significant aggravation trend, restricting the development of the jujube industry. From 2006 to 2015, on the basis of extensive investigation, the occurrence of 10 major diseases of jujube trees was systematically studied, and after a large number of field experiments, the operating calendar of comprehensive control measures for winter jujube tree diseases was formulated and implemented, and the good fruit rate of the demonstration garden was more than 95%, and the good leaf rate was more than 98%, and the prevention effect was remarkable.

1 The main symptoms and occurrence of winter jujube are infectious diseases

1.1 Date rust

1.1.1 Symptom diagnosis Jujube rust only harms the leaves, and its main symptoms are: the back of the leaf produces a punctate yellow-brown rust, and the front of the leaf is green and flower-like. Causes early leaf defoliation in severe cases (Figure 1).

Fig. 1 Jujube rust summer spore pile

1.1.2 Occurrence of regular jujube rust bacteria mainly overwinter on diseased leaves, and infect hazards through air current transmission. The disease can be reinfected many times in the field. When it is rainy and wet, the disease occurs seriously when there is rain and dew. When the rain is early and the rainfall is high, the onset of the disease begins in late July, and the onset of the disease is peak in late August and September. The jujube garden is closed, the ventilation is poor, and the environmental humidity is conducive to the occurrence of diseases.

1.2 Anthrax

1.2.1 Symptom diagnosis Anthrax mainly harms the fruit, forming brown to black-brown depression spots on the fruit, round or nearly round, and small black spots grow on the surface of the spots in the later stage, and light pink mucus is produced on it when wet. The fruit is prone to early shedding (Figure 2).

Fig. 2 The anthrax plaque is depressed, and black spores are produced in the middle of the spots

1.2.2 Occurrence of regular anthrax pathogens mainly overwinter in the disease residue and tree disease tissue, the pathogen spores are infected by wind and rain to infect the fruit from about half a month after the fall of flowers to the ripe harvesting period, but all of them begin to occur from the late stage of fruit expansion, that is, the disease has obvious latent infection in the field. The impact of the fruit in the morning and evening and the severity of the disease depends on the morning and evening of the rainy time and the duration of the rainy and high humidity environment, and the disease occurs early and heavily when the rainfall is early, the amount of rain is large, and the duration of the high humidity environment is long.

1.3 Rotavirus disease

1.3.1 Symptom diagnosis Rotaviolia mainly overwinters on tree spots and dead branches, and the spores of the pathogen are spread by rain and infect jujube fruit from skin holes or wounds. Young fruits can be infected by pathogens from about half a month after flowering, until the ripening harvest period, but the fruit does not gradually develop disease after the white-backed stage (red circle stage), and the closer to maturity, the more serious the disease. Severe diseases occur in rainy and wet years (Figures 3, 4).

Fig. 3 Jujube rotifer disease, the lesion is not concave, there are concentric chakra

Fig. 4 Rotavirus disease spots on branches

1.3.2 Regular rotifer disease mainly overwinters on tree body spots and dead branches, and the spores of the pathogen are spread by rainwater and infect jujube fruit from skin holes or wounds. Young fruits can be infected by pathogens from about half a month after flowering, until the ripe harvest period; generally after the fruit enters the white ripening stage, the disease gradually occurs, and the closer it is to maturity, the more serious the disease. Rainy and wet years or serious occurrence of environmental diseases.

1.4 Concretosis

1.4.1 Symptom diagnosis of constriction disease is also called "tin disease", "dry waist disease", "fog copy disease", which only harms the fruit. The fruit creases, wilts, and falls off easily from the middle, or turns white from the shoulders, then yellow, and finally brown, and the flesh of the fruit rots (Fig. 5).

Fig. 5 Jujube fruit has yellow shoulders and then turns brown

1.4.2 The occurrence of regular fruit shrinkage fungus is a weak parasitic fungus, which is widely present in jujube gardens and mainly affects the fruit through wind and rain. The young fruit stage can be affected from the fruit stage to the fruit stage, but the fruit onset gradually begins from the white ripening stage, and the near-ripening stage enters the peak period of the disease. Rainy and wet, foggy and heavy dew are the main conditions that induce the disease, and the low-lying terrain and densely planted jujube gardens have a more serious incidence.

1.5 Nigra

1.5.1 Diagnosis of black spot disease mainly harms fruits and leaves. Generally, the top leaves of the branches occur first, and brown or black necrotic spots appear on the diseased leaves (Figure 6); the main feature of jujube fruit is the formation of black spots on the fruit surface (Figure 7), which can be divided into four symptom types: reddish brown, gray brown, dry rot, and scab.

1.5.2 Occurrence of regular black spot fungus is a weak parasitic fungus, mainly overwintering on the tree body, with the help of wind and rain and air transmission, mainly through wound infection hazards, especially green blind bugs and other stinging harm to wounds is the most important. From the young fruit stage (when the fruit grain is the size of a bean grain) to the white ripening stage, it can be infested. Serious diseases occur in rainy and humid environments, severe diseases occur in green blind bugs in jujube orchards, and diseases occur in jujube trees with iron deficiency yellow leaves.

1.6 Dry rot

1.6.1 Symptom diagnosis of dry rot disease is also called rot disease, branch blight, dry rot mainly harms the branches, generally less caused by dead trees, but the spread of the disease spreads very quickly. In the early stage, yellow lesions appear in the cortex, but the epidermis is necrotic, and then it deepens year by year, and the color deepens year by year, and generally does not rot to the xylem. The perennial disease spots are black and partially cracked, and the texture of the spots is hard, and when the spots rot to the xylem and the spots circle the branches for 1 week, the branches die (Figure 8).

Fig. 8 Dry rot spots in 1 to 2 years, the color deepens year by year

1.6.2 Regular decaying pathogens mainly overwinter in the branches and spots, spread by wind and rain, and infect from the wound. The pathogen is a weak parasitic bacterium that lurks on dead branches, dry piles, around wounds and necrotic tissues, and expands to form spots when the tree is weak. Extensive management of jujube orchards and weak tree strength are the main factors that induce decay.

2 Comprehensive prevention and control measures

2.1 Cultivation measures

2.1.1 Reasonable pruning through pruning, to remove diseased insect branches, dead branches, aging branches and over-dense main branches. Adjust the tree structure by pruning to keep the garden ventilated and transparent.

2.1.2 Strengthen fertilizer water management Strengthen the fertilizer water management of jujube orchards and improve the disease resistance of trees. After the autumn application of base fertilizer, the base fertilizer is mainly decomposed farm manure, the germination stage topdressing is mainly fast-available nitrogen fertilizer, and the amount of nitrogen fertilizer should be reduced during the expansion of the fruit, and the potassium fertilizer and phosphorus fertilizer should be increased.

2.2 Artificial control

2.2.1 In the autumn and winter of Qingyuan, the garden shall be cleared in time to remove the cut off branches, zombie fruits and fallen leaves, and burn them in a concentrated manner, and at the same time, combined with deep turning, destroy the wintering sites of diseases and insect pests and reduce the overwintering base.

2.2.2 The bark-scraping trunk and the warped skin slit at the main branch are the main overwintering sites for pathogenic bacteria. In winter and spring, the thick bark of the main trunk and the lower part of the main branch is scraped off and burned in a concentrated manner.

2.3 Chemical control

2.3.1 Do a good job in disease and pest detection and reporting Scientific medication according to the occurrence of diseases and insects combined with the natural enemies of orchards, and make accurate monitoring and reporting of major diseases and insect pests. In the juvenile stage, the harm of prickly insects such as green blind bugs is well controlled, and the infestation route of pathogenic bacteria is reduced.

2.3.2 When using pesticide spraying correctly, it is necessary to make all parts of the tree body uniformly medicated, especially the back of the leaf, the fruit surface and other parts. In the same growing season, different types of pesticides are used alternately to avoid the occurrence of drug resistance and improve the prevention and control effect.

2.3.3 The safe use of pesticides is generally used from early in the morning to before 10:00 a.m., or after 4:00 p.m., and pesticides are retained on the tree body for a longer period of time, which is also safer for people and crops. In the high temperature and rainy season, Bordeaux liquid should be used with caution [Jishan Huayao].

2.4 Rational mixing of pesticides

The rational mixing of pesticides can expand and improve the effect of pesticide use, but some pesticides will seriously affect the efficacy of drugs when mixed, and even serious drug harm. For example, stone sulfur compound and Bordeaux liquid can only be used alone, and cannot be mixed with other pesticides or acaricides.

2.5 Annual calendar of integrated control of jujube tree diseases

Based on the requirements of pollution-free production and the occurrence of pesticides and the occurrence characteristics of diseases, after a large number of tests, the comprehensive control of winter jujube tree diseases has been formulated. From 2007 to 2016, we arranged 10 to 15 experimental demonstration gardens in Cangxian County every year, and all the demonstration gardens were operated according to the operating calendar we formulated, and over the past few years, the good fruit rate of the demonstration garden was more than 95%, and the good leaf rate reached more than 98%, and the prevention effect was remarkable. The operation history of the integrated control of jujube tree diseases is introduced as follows (Table 1).

Note: The specific medication time is flexibly mastered according to the weather, the interval between medication in rainy and wet weather is appropriately shortened, and the interval between medication in dry and rainy weather is appropriately extended.