Fruit shrinkage disease of jujube and its control methods

1. Symptoms: during the onset of jujube fruit shrinkage disease, a yellowish halo (ring) is first produced on the shoulder or waist of the fruit, which gradually expands into irregular sunken spots, the pericarp becomes infiltrating water stains, there are evacuated needle-like round brown spots, and the flesh becomes yellowish, soft, spongy and necrotic, the fruit shrinks, tastes bitter, and is unedible:

2. The preliminary study on the incidence law showed that jujube fruit shrinkage disease was a bacterial disease, and the pathogen overwintered mainly on the diseased fruit on the ground. 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 peak of the disease is fruit coloring and daily average temperature of 23-26 ℃ from July to September. If there is continuous rain or sunny rain or foggy weather, it is easy to break out. Wind and rain cause friction and trauma to leaves and fruits, and suck insects such as scale, mite, leafhopper, stink bug and peach heart borer, which are susceptible to disease: usually too dense planting, too much nitrogen fertilizer, excessive tree potential, unreasonable intercropping, improper pruning, etc., resulting in shaded crown, poor light ventilation, etc., increase the spread of diseases by pests, and the incidence is higher.

3. Prevention and control methods (1) chemical control. Spraying is the key at the beginning of the disease 15-20 days before the jujube fruit is fully expanded and begins to color and mature. Spray once every 7-10 days, 2-3 times in succession. The main agents are streptomycin 70-140 units / ml, oxytetracycline 140 units / ml, kanamycin 140 units / ml, 80% Dasheng Mmuri 45 wettable powder 600 × 800 times. (2) clear the garden and sterilize. After fruit harvest every year, thoroughly remove the fallen diseases, pests and rotten fruits in the jujube garden, burn them centrally, eliminate the base number of overwintering pathogens, and reduce the incidence next year. (3) Pest control. Strengthen the control of pests such as scale and mite, prevent the damage caused by strong wind, reduce the wound of jujube fruit and reduce the infection rate of bacteria. (4) strengthen field management. Do not interplant tall crops in jujube orchards and crops with the same diseases and insect pests as jujube trees; prune reasonably, improve light conditions, strengthen ditch drainage, reduce soil and air humidity, re-apply organic fertilizer, improve soil structure, increase phosphorus, potassium, calcium and boron fertilizer, properly control nitrogen fertilizer, reasonably supply shaking, promote the coordination of water and fertilizer, enhance tree potential, and improve disease resistance.