Jujube rust prevention and treatment was in July

Jujube rust, also called jujube, is an epidemic disease that infects the leaves of jujube trees. Often cause a large number of deciduous fruit during fruit enlargement, easily lead to shrinkage of jujube, sugar content of fruit pulp greatly reduced, the majority of jujube fruit lost food value, severely affected years or even no harvest. After the early fall of the diseased plant, secondary sprouting occurred, which in turn led to a decrease in production in the following year.

â–²Injury symptoms

The pathogen of jujube rust is jujube rust fungus in the fungus basidiomycotina. It mainly affects the leaves. The pathogenic bacteria mainly overwinter on the diseased leaf in the summer spore heap, and it can also cause perennial hyphae to overwinter in diseased buds. In the summer of the following year, spores spread to new leaves by wind and rain, and then directly invade from the front and back of the leaves, causing initial infection. In the early stage of the disease, the back of the leaf was scattered or raised with small yellowish pustules, ie the uredia spores of pathogens. Lesions mostly occur on both sides of leaf veins, tip and base of leaf. Concentrated on both sides of veins, often many into strips or sheets, when it matures, the epidermis ruptures, yellow powder is scattered, the leaves gradually lose their luster, covered with yellow brown spots, and finally dry, deciduous. Disease incubation period is generally 7 to 15 days. The disease starts from the lower part of the canopy and gradually spreads upward. In severe cases, the leaves of the whole tree fall off, causing the jujube fruit to fail to mature normally.

â–²The law of occurrence

The severity of jujube rust is closely related to the amount of rainfall from July to August. When the relative humidity of air from July to August reaches 70% to 80%, the incidence is heavier when the temperature is above 30°C. The incidence rate can reach more than 80%. According to observations, the total rainfall in July reached 250 mm. When the average daily temperature reached 30°C, the disease occurred early and heavier. When the rainfall is less than 130 mm, the onset is light and late. Any zao forest with low-lying topography, inter-planted corn and other high-stem crops, or jujube forest with irrigated land can cause heavy rust, and the incidence rate is 67%. On the other hand, in the jujube forests of low-stem crops such as mountain or intercropping peanuts, rust occurs relatively lightly and the incidence rate reaches 53%. The occurrence of jujube rust from the onset to the deciduous period will take about 30 days, resulting in the defoliation of the whole tree will take about 2 months.

â–² Prevention methods

1. Chemical control. Mainly in July of the date of the rust of the date rust spraying control. A 200-300-fold Bordeaux mixture or zinc-copper Bordeaux mixture was sprayed once every 15 days. The popular year can be sprayed again in early August, which can effectively control the occurrence of date rust. Secondly, it can be used to prevent and treat 1500 times of Buerfeng, and all have good results. 2. Strengthen cultivation management. To build a new date garden, planting jujube trees should not be too dense, and the thick growing branches should be trimmed timely so as to facilitate ventilation and light transmission and enhance tree vigor. The rainy season should pay attention to timely drainage and reduce the humidity of the jujube garden. Late autumn clear leaves in time, concentrated burned or buried in order to reduce the source of overwintering bacteria. Jujube trees should not be planted between high-stalk crops. 3. Root recovery fertilizer. Jujube top dressing has the effect of improving photosynthesis and fruit setting rate, and can also prevent and control jujube rust. In the jujube infection period, spray 0.5% urea solution or Tianrun No. 1 2 or 3 times. 4. Note. Spraying requirements are uniform, thoughtful and sufficient. Spraying time should be in the early stage of disease or rust on the appropriate date.

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