Prevention and control of white stripe feather disease of Hawthorn

Hawthorn white feather disease is an important root disease of Hawthorn trees in old Hawthorn producing areas, and it is the main cause of death of old and weak trees.

First, the symptoms show that after the infection, the root is wrapped around a white to gray-white silk mesh, that is, the fungal cord of the pathogen, and the ground rhizome produces a gray-white velvet. The shape of the leaf becomes smaller, the leaf margin is scorched, and some or all of the branchlets and big branches die.

Second, the route of transmission and disease conditions are mainly overwintering in the soil with hyphae, rhizomatous fungal cords or sclerotia remaining on the diseased roots. When the conditions are suitable, the sclerotia or rhizomatous fungal cord grows vegetative hyphae and invades from the root epidermis. The pathogen first infects the new root, then spreads gradually, and the injured fine root mildew is rotten. The germs are transmitted through contact with the health department or through long-distance transmission of diseased seedlings. The disease mostly occurs from July to September. Its occurrence is related to soil moisture and pH, especially when the humidity is the greatest, the orchard or nursery is low-lying and moist, the disease is serious when the drainage is poor, the planting is too dense, the planting is too deep, the soil is too thick, the root is injured during tillage, and poor management can easily lead to the weakening of tree potential, lack of soil organic matter, strong acidity and so on.

Third, control methods (1) select and plant disease-free seedlings. Select and plant disease-free seedlings during the establishment of the garden. if it is determined that the seedlings are infected, they can be soaked in 10% copper sulfate solution or 20% lime water, 70% methyl carbendazim wettable powder 500 times solution for 1 hour before planting. It can also be soaked in 47 ℃ constant temperature water for 40 minutes or 45 ℃ constant temperature water for 1 hour to kill the germs in the roots of seedlings. (2) digging trenches for isolation. Dig a ditch 1 meter deep outside the diseased plant or disease area to block it to prevent the disease from spreading around. (3) strengthen cultivation and management, enhance tree potential and improve tree disease resistance. Adopt the technology of formula fertilization, not partial application of nitrogen fertilizer, appropriate application of potassium fertilizer, so that the proportion of nitrogen, phosphorus and potassium is appropriate. During the full fruit period, low-lying and wet orchards or plots should pay attention to drainage. Reasonable pruning to prevent the phenomenon of big and small years. Strengthen the prevention and control of other diseases and insect pests. (4) treatment of diseased trees. Find the diseased tree, first dig to the base of the main root, peel off the root soil, look for the stem disease spot of the root, and then trace the disease point of the main root, lateral root and branch root from the disease spot down. For rotten roots, they should be sawed or cut off from the root base, and the diseased skin on the rhizome spot should be carefully scraped off. If most of the root system is sick, it is necessary to thoroughly remove all the diseased roots, and carefully protect the healthy roots in the process of removing the diseased roots. Wounds should be smeared with high concentrations of fungicides or sprayed, and then protected by Bordeaux solution. In addition, 40% pentachloronitrobenzene powder can be selected for 40% 50 parts of new soil, fully mixed and applied to the roots, for 8-year-old 10-year-old trees, 0.25 kg of soil for each plant. (5) rotation in nursery, seriously ill nursery should rotate with gramineous crops for 5 ~ 6 years before continuing to raise seedlings.