1. Symptoms and hazards of apple blight
Apple dry blight mainly harms the newly planted apple saplings, the disease is generally 10 30 cm from the ground, in the spring on the trunk or treetops to form 2 8 cm long oval lesions, mostly along the edge of the longitudinal crack and sag, separated from the tree, when the disease is aging, the edge is rolled up, the diseased skin falls off, the lesion surrounds the new shoot for a week, the branch withering, it can cause the young tree to die, and the lesion produces small black spots.
If the humidity is high, a yellow-brown filamentous spore horn will emerge from the diseased area, and the lesions will become dark brown from the base and spread upward, and the lesions will be reddish-brown.
2. Transmission routes and causes of apple wilt
The blight fungus or mycelium overwinters in the diseased area, and releases conidia in the next spring when it encounters rain or irrigation water, and spreads through water, which is easy to induce when the tree is weakened or the branches lose water and shrink and are damaged by frost.
3. Methods for the prevention and control of apple dry blight
1. Select disease-free apple seedlings, and strengthen management to promote the growth of seedlings and improve disease resistance.
2. Do not plant tall crops in the orchard, and do a good job of whitening in winter to prevent frost damage and sunburn.
3. Check the apple tree in time before germination in spring, if it is found that the diseased branches or spots should be removed in time, and brought out of the orchard for treatment to reduce the source of disease.
4. During the occurrence of the disease, the agent can be sprayed every half a month for prevention and control, and the available agents are: 40% carbendazim suspension, 36% thiophanate-methyl suspension 500 times liquid, 50% thiophanate-methyl sulfur suspension 800 times liquid, 50% mixed sulfur suspension 500 times liquid.