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Other answers
Pathogens are mainly transmitted by various grafting methods and leafhoppers that harm jujube trees. The contact between soil, pollen, seeds, juice and diseased healthy roots cannot spread diseases. Grafting and root grafting can occur in the same year before the end of June, and symptoms will appear in the second year after the end of June. The more skin grafts, the faster the onset; Those with arid and barren soil, poor fertilizer and water conditions, extensive management, serious pests and diseases and weak trees are seriously ill; On the contrary, it is light. Different jujube varieties have different disease resistance. At the initial stage of the disease, it usually starts from one or several big branches and tillers, and the symptoms spread from local to the whole tree. After the onset, young trees can die in 1~2 years, and big trees can die in 4~5 years. The seedlings died that year after infection.
4. Prevention and control points
(1) Select disease-resistant jujube varieties and disease-resistant jujube varieties with jujube kernel as rootstock.
(2) scion disinfection: For scion with disease, use 1000? Soak in mg/kg tetracycline hydrochloride solution for half an hour for disinfection and sterilization.
(3) adopting scions, buds or roots for propagation in disease-free jujube areas; Cultivate disease-free seedlings; Once the diseased seedlings are found in the nursery, they should be pulled out immediately.
(4) Eradication of diseased trees and prevention of infection: timely and thoroughly eradicate diseased trees and eliminate infection centers at an early stage; When the diseased trees are planed, the big roots should be planed together to avoid germination.
(5) Strengthen the management of jujube trees: increase the application of organic fertilizer and alkaline fertilizer, timely irrigation, enhance tree vigor and improve disease resistance.
(6) Trunk girdling: Because the transmission of pathogens in the trunk is directional, before the juice flows out in spring, the middle and lower parts of jujube trunk can be girdled with a width of 3 ~ 5cm to prevent the pathogens from spreading from bottom to top.
When the blade is damaged, it starts from the middle and lower blades and gradually spreads to the upper part; At the beginning of the disease, white hyphae appear on the back of leaves, and in severe cases, white hyphae and white powder (pathogen conidia) appear? Covered on the back of the leaf, the front of the leaf has irregular spots of faded green or yellowish brown. The damaged leaves are dark brown in the later stage and easy to fall off. When the tender branch is damaged, white hyphae and white powder cover the whole branch, and the tender leaves shrink into yellow-brown and die. Fruit damage is the most serious in the fruit expansion period, followed by the young fruit period and less in the flowering period. In severe cases, white hyphae and white powder can cover the whole fruit. After the fruit is damaged, the skin becomes numb, shriveled, brown or yellowish brown, and it is easy to fall off or die.
Pathogens overwinter in diseased branches, diseased leaves and thousands of hard fruits. During the leaf spreading period of jujube tree in the following spring, the pathogen produced a large number of conidia, which were spread by wind and rain and reinfected many times. High temperature in summer is not conducive to the growth of pathogenic bacteria. It is rainy and humid in spring and autumn, and the orchard is gloomy, with poor ventilation and light transmission.
4. Prevention and control points
(1) Agricultural control: thoroughly remove dead branches, fallen leaves and hard fruits in the garden in winter and spring, bury or burn them, and eliminate overwintering bacteria sources. Strengthen the management of jujube orchard, prune it reasonably and keep the orchard ventilated and transparent; Drainage in time after rain to prevent water accumulation in the orchard.