What are the symptoms and characteristics of jujube rust? How to prevent and cure it?

In the process of jujube growth, jujube is easily damaged by jujube rust, which mainly threatens the leaves of jujube and causes early defoliation, which leads to the decrease of sweetness and fruit drop of jujube, which leads to the reduction of growers' yield. Jujube rust only occurred on the leaves, at first scattered light green dots on the back of the leaves, and then gradually protruded in dark yellowish brown, that is, the summer spore pile of the pathogen. What are the symptoms and characteristics of jujube rust? How to prevent and cure it?

What are the symptoms and characteristics of jujube rust?

1. Symptoms of jujube rust

Jujube rust only occurred on the leaves, at first scattered light green dots on the back of the leaves, and then gradually protruded in dark yellowish brown, that is, the summer spore pile of the pathogen. The summer spore pile is irregular in shape, about 0.5 mm in diameter, and mostly occurs on both sides of the midvein, leaf tip and base. After the surface rupture, scattered yellow powder, that is, summer spores. Green dots occur on the front of the leaf corresponding to the summer spore pile, and the edge is irregular. The leaf surface is foliar, and gradually loses its luster, and finally dries up and falls off in the early stage. The fallen leaves gradually spread from the lower part of the crown to the upper part. Teliospore pile usually occurs more after leaves fall off, which is black, smaller than summer spore pile, 0.2mm in diameter, 0.5 mm in diameter, dark brown, slightly protruding, but does not break through the epidermis.

2. Characteristics of jujube rust.

The occurrence of jujube rust every year is closely related to the rainfall from July to August. When the total rainfall in the jujube area reaches 20000mm in July, the disease is early and serious. If it is less than 130 mm, the onset of the disease will be late and mild. After the outbreak of jujube rust in the county last year, the possibility of an outbreak of jujube rust this year is very high.

In all gully and beach land, irrigated land, low-lying jujube forest, or jujube forest in windy land, rust is serious, fallen leaves and fruits are serious. It takes about 30 days from the disease to the defoliation, and about 2 months to cause the defoliation of the whole tree.

Second, how to control jujube rust?

1. When clearing the garden in winter, the disease will be concentrated and burned so as to reduce the source of disease in the coming year.

2. For low-lying jujube orchards, drainage should be done to prevent the death of fruit trees caused by stagnant water in the orchards.

3. Jujube trees re-apply base fertilizer, mainly organic fertilizer, combined with phosphorus and potassium fertilizer, avoid excessive application of nitrogen fertilizer, in order to improve the disease resistance of jujube trees.

4. The jujube garden with exuberant growth should be pruned properly to facilitate ventilation and light transmission, enhance the tree potential and improve the disease resistance of the tree. Pruning is mainly branch thinning. If the new jujube heads germinated on the jujube strands and the new jujube heads germinated in the crown are not used, they should be removed in time in order to reduce nutritional consumption and improve ventilation and light transmission conditions.

5. Timely control of rust wall lice.

6. When spraying pesticides on jujube trees in July and early August, 200 times Bordeaux solution or 800 times 70% methyl thiophanate wettable powder can be used.