Occurrence and control of fruit shrinkage disease of jujube

Jujube fruit shrinkage disease, also known as black rot, is a new disease of jujube. When the disease occurs, it has a serious impact on the quality and yield of jujube fruit.

First, symptoms

The disease mainly harms the fruit, causing fruit rot and early fruit drop. At first, the injured fruit appeared a yellowish halo on the shoulder or carcass, gradually enlarged into concave irregular yellowish disease spots, and then the pericarp showed infiltrating water stains, with needle-like round brown spots, yellow and soft flesh, spongy necrosis of the diseased tissue, and dark red exocarp without luster. The diseased fruit is small, wrinkled, bitter and unedible.

Second, the law of the disease

Jujube fruit shrinkage disease is a kind of disease caused by both bacteria and fungi. Fungi are the main damage in the immature stage and bacteria are the main damage in the near mature period. The pathogen overwintered mainly in the diseased fruit. Generally, it spreads infection to damage jujube fruit during the fruit coloring and ripening period, and the bacteria invade from the fruit wound or directly penetrate the pericarp by wind and rain. The disease began in early July in the central and southern part of Hebei Province, and the peak period was from mid-August to early September. The severity of the disease was closely related to the environmental conditions such as temperature, rainfall, insect pests and varieties. 22-28 ℃ was suitable for the disease, especially in rainy or sunny day and night rain and foggy weather, it was easy to break out and cause disasters. Wind and rain caused friction and trauma to leaves and fruits, and sucked and damaged by insects such as mites, leaf cicadas, stink bugs and peach heart borer. Li jujube, Ling jujube and other varieties are more susceptible to the disease, while Dongzao and Po jujube are more resistant. In addition, partial application of nitrogen fertilizer, dense branches and leaves, unreasonable intercropping, etc., resulted in poor light ventilation, increased pest transmission and serious disease.

III. Prevention and control methods

1. Artificial control: after fruit harvest every year, thoroughly remove the diseases, pests and rotten fruits in the jujube orchard, burn them or bury them deeply, eliminate the overwintering pathogens and reduce the incidence next year.

2. Chemical control: generally, the first time can be sprayed at the end of July or the beginning of August, and then sprayed once or twice every 7 to 10 days. The main agents are streptomycin 70,140 units / ml, kanamycin 140 units / M1, oxytetracycline 140 units / ml. A 600-fold solution of 75% chlorothalonil wettable powder is available for fungal fruit shrinkage. Before the peak of the disease, spray 50% jujube fruit Ning No. 1 wettable powder 600 times liquid, the control effect is remarkable.

3. Pest control: timely control of leafhopper, tortoise scale, peach heart borer and other pests harmful to jujube trees, so as to reduce the wound of jujube fruit and reduce the infection rate of bacteria.

4. Strengthen field management: not intercropping tall crops and crops with the same diseases and insect pests in jujube orchards: reasonable pruning, improving light conditions, increasing organic fertilizer and scale potassium fertilizer, rational application of nitrogen fertilizer, boron, calcium and other trace elements to enhance tree potential and improve disease resistance of jujube trees.