In recent years, fruit growers in Shandong and Shaanxi provinces have reported that apple branches tend to grow some stings, especially at the place of delivery. Many technicians and fruit growers cannot tell what the disease is. If the disease cannot be treated in time, it will directly cause the diseased trunk or even the entire tree to rot and die. After investigation and understanding, combined with our many years of research, the disease was identified as apple trunk rot (branch type).
Apple trunk rot, also known as "rot rot", is one of the important diseases of apple tree branches.
First, the symptoms mainly invade the stems of adult plants and seedlings, but also can infect the fruit. There are three types of symptoms:
1. ulcer type. The lesion is initially irregular dark purple or dark brown spots, the surface is moist, often overflowing brown mucus. Cortical tissue decay, not to the xylem, no distiller's grains, dry spots after dehydration, depression, disease and health at the junction often cracked, vertical and horizontal cracks on the surface of the lesion, the latter part of the disease appear small black spots, small and dense than rotten . The top of the wet spores overflowed with gray spores.
2. Branches dry type. In the upper part of the senescence tree, the upper shoots become ill. The lesion initially produces dark brown or purple-brown elliptic spots. It quickly spreads up and down into depressions in the strips, reaching the xylem, resulting in dead shoots and dense black spots on the lesions.
3. Fruit rot type. The victim's fruit produces yellow-brown small lesions on the initial fruit surface and gradually expands into a dark brown concentric ring pattern. When the conditions are appropriate, the lesions spread quickly and the whole fruit can decay for a few days. Later became a black stiff fruit.
Second, the pathogenic sexual state is BotryosphaeriaribisGross.etDugger, belonging to the genus Ascomycota, and the genus Gracilaria; the capsule shell is spherical, dark brown, with a papillary orifice. Ascosporum sticks, colorless.
The asexual generations were Macrophage and Dothiorella. Conidiophores nearly spherical or oblate, light brown or dark brown. Conidia oval, unit cell, colorless.
Third, the occurrence of regular bacteria with mycelium, conidia and ascaria shells in the branches of the disease through the winter, Hunchun mycelial resumption of hyphae activities to produce conidia spread with the wind and rain, the wound, dead buds and lenticels invasion. The pathogen has the characteristics of latent infection. Only when the tree is weakened, the bacteria on the bark can spread out. When the water content of the bark is low, the pathogenic bacteria expand rapidly, so the incidence in drought years is heavy, and the incidence of Guoguang, Qingban bananas, and red stars is heavy. Red jade, marshals, Zhuguang, chicken cocks and other diseases are light.
Fourth, control methods
Strengthen management, improve tree disease resistance; choose healthy seedlings, avoid deep planting, apply enough base fertilizer when transplanting, and irrigate water to shorten the seedling-reducing period; saplings should not cause dry wounds and water loss when transporting long distances; Protect the tree body and do a good job of anti-freezing; in the early stage of disease, you can cut off the discolored diseased part or scrape off the diseased spot. Apply 10 Baume degree stone sulfur or 70% thiophanate-methyl wettable powder 100 times liquid to the wound; Before germination, spray 3 to 5 Baume degree lime sulfur or 35% ringworm eradication agent 100 to 200 times liquid and so on. Prior to germination, combined with control of ringworm, anthrax spray two 1:2:200 Bordeaux mixture or 50% withdrawn 800 times, 35% ringworm eradication agent 400 times, 50% compound carbendazim 800 times liquid protection.
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