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Common diseases of hawthorn fruit trees and their prevention and maintenance
Hawthorn moth. Artificial control: Scrape the larvae hidden in the bark in autumn to reduce the overwintering larvae. Saw off or cut off dead trees and branches and transport them to the orchard for centralized burning.
Artificial control of hawthorn: after the leaves of hawthorn fall off, before germination in early spring, combined with winter and spring seasons, the leaf sacs on hawthorn trees are cut off to centrally eliminate overwintering larvae.
Drug control: spray with 80% dichlorvos EC 1500 times solution. Secondly, it is generally sprayed throughout the park to protect trees from disinfection and sterilization and protect trees from wintering.
Harmful symptoms: 2-year-old fruit piles get sick first, the cortex turns brown, the whole pile rots, and then spreads down the pile. When the diseased spot extends to the base of the fruit branch, the fruit branch of that year quickly loses water, withers and dies. Dead branches are not easy to fall off and can stay on trees 1 year. The lesion is dark brown, and the boundary between diseased tissue and healthy tissue is clear. In the later stage, it contracts and sinks, forming dense taupe particles. Under wet conditions, milky white filaments overflow from the top of small particles, which is the conidia angle of pathogenic bacteria.
Occurrence factors:
(1) Host resistance: With the increase of tree age, the disease tip rate of trees entering the fruiting stage gradually increased. When the diameter of fruit pile foundation is less than 0.3 cm, the disease is serious. Trees with weak growth are more seriously ill. The growth potential of lumen branches is weak, and the rate of diseased branches is often high.
(2) Host resistance: young trees that do not bear fruit grow vigorously and do not get sick; With the growth of tree age, the disease tip rate of big trees in fruit-bearing period gradually increased.
(3) Germ source: The fungus is a weakly parasitic fungus, which can be carried by fruit piles, but whether it is pathogenic or not depends on the growth potential of branches. Generally, the diseases of trees with strong growth are lighter, and those with weak growth are more serious. For the same tree, the growth potential of the outer branches of the crown is strong, and the growth potential of the inner branches is weak; Young fruit trees have strong growth potential, while old fruit trees have weak growth potential, and the rate of diseased branches of the latter is often higher than that of the former.
(4) Cultivation: The occurrence of diseases is closely related to soil conditions and management level, and the incidence rate is high in mountainous areas with thin land and extensive management; The incidence of garden with thick soil layer and good management conditions is low.
Control methods: agricultural control: ① After harvesting, dig deep and expand holes, and apply 200-250kg base fertilizer to each plant. Before flowering for 2-3 weeks, after flowering for 65,438+00 days, before fruiting in the middle and late June, and before fruit coloring in the middle of August, properly topdressing nitrogen, phosphorus and potassium fertilizer, and then spraying new high-fat film to enhance the utilization rate of fertilizer efficiency, so that the rate of diseased shoots in that year decreased obviously. In addition, strengthening pruning, promoting ventilation and light transmission, preventing partial migration of results and controlling age are also effective measures to control the disease tip. (2) Cut off diseased shoots in time, burn them centrally, reduce the source of bacteria and control the occurrence of diseases. And spray the trees in the whole garden for comprehensive disinfection and sterilization to protect the trees from overwintering safely.
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