Occurrence and control of fruit shrinkage disease of jujube

I. symptoms and hazards

Jujube fruit shrinkage disease, also known as jujube wilt disease, jujube fog wilt disease and so on, is one of the main diseases in major jujube areas in China. The jujube fruit with fruit shrinkage disease first appeared yellowish brown irregular discoloration spots on the shoulder or carcass, and then the pericarp appeared waterlogged, khaki, the edge was unclear, and in the later stage, the pericarp became dark red, contracted, and had no luster. Brown spots appear in the pulp disease area from outside to inside, and the flesh is yellow and soft. The sick fruit tastes bitter. The fruiting stalk becomes brown or dark brown. The whole diseased fruit is thin and falls off before ripening. After the pathogen of jujube shrink disease invaded the normal fruit, the symptoms of the damaged fruit generally included halo, water stain, coloring, atrophy and shedding, but this was not entirely the case. fruit shrinkage occurred in the early stage of jujube fruit growth, and the diseased fruit fell off in the waterlogging period; fruit shrinkage disease occurred in the middle stage of growth, and some of the diseased fruit fell off when it was semi-red; while fruit shrinkage disease occurred in the late growth stage of jujube fruit, and most of the diseased fruit entered the harvest period without falling off in the atrophy period.

Second, the law of the disease.

Recent studies have shown that fruit shrinkage is a disease caused by bacterial infection. The disease is directly related to the damage of jujube fruit skin. In addition to the natural wear and tear of jujube fruit wounds, the disease is mainly caused by piercing and sucking mouthparts pests, such as ticks, leafhoppers and stink bugs. The disease is also related to the development period of jujube fruit. In North China, the disease usually occurs when the jujube fruit is white to colored. From the perspective of climatic conditions, when the temperature is between 26 ℃ and 28 ℃, the disease is easy to break out when it is rainy at night or sunny at night. Fruit shrinkage disease occurs more frequently in a spot, several trees in a jujube orchard and several branches in a jujube tree and so on. In addition, fruit shrinkage disease and anthracnose often occur on the same jujube fruit or in the jujube orchard at the same time, which is sometimes difficult to distinguish. The main difference between the two kinds of diseased fruit is whether the kernel of jujube fruit blackens or not. Jujube fruit only suffering from fruit shrinkage disease, the core generally does not change color, but once infected with anthracnose, its core will turn black.

III. Prevention and control techniques

1. Strengthen pest control and prevent the occurrence and harm of piercing and sucking pests in time, such as peach heart borer, shell insect, stink bug, tick and leafhopper, etc. In the early stage, insecticides were sprayed mainly to control bud weevil, leafhopper and jujube inchworm; in the later period from August to September, combined with insecticides such as cypermethrin and Teprazole, the control effect on jujube fruit shrinkage disease was more than 95%.

2. Strengthen the soil management of orchard, keep the soil moist during the period of changing color to red of jujube fruit, and prevent or reduce the occurrence of fruit cracking.

3. Spraying "jujube fruit anti-cracking and anti-rot agent" (developed by Cangzhou Academy of Agriculture and Forestry) before and after jujube fruit turning red to prevent fruit cracking and reduce the number of fruit cracking. Each 10 ml, directly spray the whole tree with 25 kg of water, once every 7 to 10 days, 2 times for 3 times.

4. Before and after the onset of the discoloration and red period of jujube fruit, spray 50% DT fungicide 500x solution or 12.5% Teprazole powder 3000 times solution, every 7 to 10 days, spray 3 times 4 times. The whole tree was sprayed with 200IU / ml of streptomycin (i.e. 10 million IU / ml of water) or 200IU / ml of oxytetracycline and 140IU / ml of kadamycin. It was sprayed once every 7 days for a total of 2 times. As the aqueous solution of the above-mentioned agents is easy to fail. Especially streptomycin, so it is best to use these agents now.