How to prevent and control jujube fruit shrink disease? A full analysis of the key technical points

Jujube fruit shrink disease is a new disease of jujube trees, often occurring together with anthracnose. When this disease breaks out severely, it causes reduced yields in mild cases and total crop failure in severe cases, and in recent years it has caused huge losses in the jujube-growing areas of our city.

The disease mainly damages jujube fruit, causing fruit rot and fruit drop. It occurs during the coloring stage of jujube fruit; in our city it begins in mid-to-late July, and mid-to-late August is the peak period of the disease. Affected jujube fruit first shows a pale yellow halo on the fruit shoulder and body, which then gradually expands into round or irregular water-soaked discolored lesions, with a round brown spot in the center; the flesh in the diseased area becomes soft and shrunken, and diseased fruit tends to drop early. Diseased fruit is small, wrinkled, and thin, and the diseased tissue becomes spongy and necrotic, tasting bitter and losing its food value. The occurrence of this disease is related to factors such as temperature, rainfall, and the development stage of the jujube fruit. When the jujube fruit enters the coloring stage and the ten-day average temperature is 23oC-26oC, rainy or foggy weather makes this disease prone to breaking out into disaster.

There is still no definitive conclusion on the pathogen causing jujube fruit shrink disease. One view holds that it is caused by the bacterium Erwinia jujubovora, another says it is caused by the fungus Coniothyrium fuckelii, and some believe the two pathogens cause damage together.

Prevention and control of jujube fruit shrink disease should strengthen integrated management. The main techniques are:

1. Scientific management. Apply more organic fertilizer and phosphorus-potassium fertilizer, apply less nitrogen fertilizer, carry out rational intercropping, avoid intercropping with tall-stemmed crops, improve ventilation and light conditions in the jujube orchard, and set an appropriate amount of fruit, so as to strengthen tree vigor and improve the jujube tree's own disease resistance.

2. Clean the orchard and eliminate sources of inoculum. In autumn and winter, thoroughly remove diseased and rotten fruit from the jujube orchard and handle them in a centralized way to reduce sources of inoculum. Before jujube trees bud, spray the whole orchard with 3 to 5 degrees Baume lime-sulfur mixture.

3. Spray pesticides rationally. According to temperature and rainfall conditions, spray the first application from late July to early August, then spray 2 to 3 more times at intervals of about 10 days. The 10 to 15 days before jujube fruit harvest is the key period for control. Currently, the relatively effective agents are: for bacterial fruit shrink disease, agricultural streptomycin 70 to 140 units/ml, oxytetracycline 140 to 210 units/ml, and kanamycin 140 units/ml can be used; for fungal fruit shrink disease, 75% chlorothalonil wettable powder 600 times can be used. According to experiments, spraying 50% Jujube Fruit Shrink Ning No. 1 wettable powder 600 times before the disease peak has an obvious control effect. When spraying, it must be uniform and thorough, with fine droplets, so that the entire fruit surface is covered with the pesticide, and if it rains, re-spray promptly.