symptom diagnosis
Purple-patterned feather disease mainly damages the roots, mostly starting from fine branches, and gradually extending upwards to the base of the main root and the root neck, even above the ground.
Its main symptoms and characteristics are: there are many lavender cotton-like hyphae or hyphae wrapped around the surface of the diseased root. When conditions are suitable, a dark purple thick tapered mycelium film will form around the diseased part. nuclear. In the late stage of the disease, the cortex of the diseased root is rotten, and the xylem is rotten, but the cork does not rot and sheaths the root outside the root. It is easily broken when pinched, and the rotten root has a strong mushroom smell. For mildly diseased trees, the tree vigor is weakened, the germination is late, the leaves are yellow and fall early; for severely diseased trees, the branches die, and even the whole tree dies.
Pathogens and occurrence characteristics
Purple plume disease is a higher fungal disease caused by Helicobasidium mompa. The pathogen can infect various fruit trees, forest trees and crops such as apples, pear trees, peach trees, pagoda trees, sweet potatoes, and peanuts. The pathogen survives the winter in the diseased plants, diseased residues and soil in the field, and the fungus cords and sclerotia can survive in the soil for 5-6 years.
In orchards, the disease is mainly spread through the contact of diseased and healthy roots, the movement of diseased residues and soil with bacteria; long-distance transmission is mainly through the transportation of seedlings with bacteria. The pathogen directly penetrates the root epidermis to infect, and can also invade and cause damage from various wounds.
Robinia pseudoacacia is an important host of the fungus, and orchards near Robinia acacia or old woodlands, river beaches, and ancient tomb cemeteries are prone to occurrence of purple plume disease; orchards where sweet potatoes and peanuts are planted between rows of fruit trees are likely to cause the occurrence and spread of the disease ; Orchards with low-lying terrain and prone to wet and waterlogged areas were severely damaged.
Prevention and control technology
Cultivating and using disease-free seedlings and paying attention to previous cropping and intercropping in the orchard are key measures to prevent the occurrence of purple plume disease; timely detection and treatment of diseased trees are important measures to avoid dead trees.
(1) Cultivate and utilize disease-free seedlings. Don't use old orchards, old nurseries and old woodlands where black locusts have been planted as nurseries. When transporting seedlings, check the nursery and resolutely not use the seedlings from the sick nursery. After careful inspection before planting, it is found that the diseased seedlings must be completely eliminated and burned, and the remaining seedlings must be disinfected with chemicals. Use copper calcium sulfate or copper sulfate solution to soak seedlings for disinfection, which has a better bactericidal effect.
(2) Pay attention to the previous cropping and intercropping of the orchard. Try not to use the old woodland, river beach, and ancient tomb cemetery to rebuild the orchard. When such a place must be used, the soil should be disinfected. The method is: cover the soil with a plastic film in summer, and suffocate the germs at high temperature; or fallow or rotate non-host plants for 3 to 5 years to promote the death of the germs surviving in the soil. In addition, do not intercrop host plants such as sweet potatoes and peanuts in the orchard to prevent intercropping plants from carrying the disease.
(3) Treat the diseased tree in time. First, scrape off the diseased tissue thoroughly, remove the diseased body and burn it outside the garden, and then apply medicine to protect the wound. Effective medicines such as: copper humate, copper calcium sulfate, methyl Thiophanate, lime sulfur mixture, etc.; secondly, disinfect the soil in the root zone of the diseased tree by irrigation. Commonly used effective agents are: dysonium, copper calcium sulfate, captan, thiophanate-methyl, etc.
(4) Other measures Increase the application of organic fertilizer, scientifically adjust the amount of fruit, cultivate the vigor of the tree, and improve the disease resistance of the tree. After the diseased tree is treated, the roots are bridged or replaced in time to promote the recovery of the tree. At the same time, a blockade ditch (50-60 cm deep and 40 cm wide) is dug around the diseased tree to prevent the spread of the disease.
