In the fruit industry production, many fruit farmers pay more attention to the prevention and control of the disease of the shoots and shoots, and the prevention and control measures are relatively effective, while the root diseases are ignored. In fact, the prevention and control of root diseases is as important as the prevention and control of some diseases on the ground. The main disease symptoms and prevention methods that damage the roots of fruit trees are as follows:
Chalk disease
The disease occurs in the root neck and roots and can spread to the lower leaves when conditions are appropriate. The roots and necks become brown and rot, gradually spreading and spreading, producing a white silky filamentous film, which is mostly radial, and the edges are especially obvious. The filamentous hyphae can spread to the soil near the root neck. In severe cases, the roots and necks of the fruit trees are full of soil. White hyphae, which later form sclerotia on the mycelium film, the sclerotium is initially white, gradually deepening into yellow, brownish brown until dark brown. The cortex of the susceptible part caused the leaves to die and fell off. In severe cases, the whole plant died. In the humid condition of moisture, the hyphae can directly spread to the lower leaves, producing a large number of white silk membranes, surrounding the lower branches and leaves, causing water-stained spots on the leaves, and producing hyphae on the silk film.
Infectious pathogen: The disease is a fungal disease, and the pathogen is a fungus of the genus Hymenoptera. The optimal temperature for pathogen development is 32~33°C, the highest temperature is 40°C, and the lowest is 8°C. The acid and alkali resistance range is from pH 5.0 to 9.0. There are more than 200 species of pathogens, and the hyphae or sclerotia survives in the soil, sick bodies and weeds. The sclerotia survives in the soil for more than 4 years, but the survival period is very short under high humidity conditions. Resistant to water. The pathogen spreads in the soil with hyphae, and the long-distance transmission is caused by artificial water such as running water or pathogens and diseased soil.
Root disease
The main manifestations of root disease are: the leaves of the infected fruit trees turn yellow, early fall or the leaves become smaller, the branches and leaves are sparse, the branches wither and die; some fruit trees will flow gel in the rhizome. In the root layer of the diseased root of the fruit tree, black-brown rhizomes can be seen on the surface of the diseased root and in the soil. Both young trees and adult trees can be infected. The pathogenesis is: a large number of spores produced by the subfamily of the ring fungus mature, and spread with the airflow, flying on the residual pile of the fruit tree, under suitable environmental conditions, the mycelium grows and extends from the stump to the root. In addition, the roots of the roots were expanded and spread in the topsoil, and finally invaded into the roots, causing the main roots and lateral roots to be infested at the same time, causing the fruit trees to wither and die.
Infected pathogen: The pathogen of fruit tree root disease is caused by the infection of the fungi, and the diseased part often has piles of fruiting bodies. The symptoms of the aboveground part are as follows: the local branches or the whole plant leaves become smaller and thinner, gradually yellowing and falling off, the new shoots become shorter, the fruits become smaller, and the taste is worse.
Root white rot
The affected area showed lavender, followed by black patches, and the plaque gradually turned white. Some fruit trees have a fat flow phenomenon at the roots. The aerial part of the diseased plant showed that the leaves turned yellow-green or yellowish, and the leaf shape was short, early, and withered. After the root rot damages the fruit trees, the spread is mainly through the contact of the roots with the healthy roots. After the disease occurs, it spreads to the surrounding areas, causing other fruit trees to feel sick, and both young trees and old trees can occur.
Root rot
After the fruit tree is susceptible, the surface of the diseased root is purple or red, and the leaves of the diseased plant are wilting and curling. The leaves are dry and dry, the branches are dry, the cortical necrosis is easy to be stripped, and finally the whole plant wither and die.
Infected pathogen: caused by Fusarium infection. The hyphae or sclerotia of the pathogen is lurking in the soil, and hyphae are produced when the environment is suitable, so that the fruit tree is infected after being contacted by the disease. A variety of fruit trees have the potential to be infested. There is also a bacterial root rot in the production of fruit trees. Its pathogen is a kind of bacteria. When the roots are damaged, it forms a large tumor like a walnut and a small bean. The damaged fruit trees are short, the leaves are yellow, the fruit is small, and the tree age is shortened.
Purple feather disease
The disease mainly damages the roots of the fruit trees, and the fine roots first develop, and then gradually spread to the lateral roots and the main roots to the base of the trunk. At the beginning of the diseased root, yellow-brown amorphous plaques were formed, and the internal cortical tissue showed brown lesions. The surface of the diseased root has a thick layer of dark purple villous hyphae, and has dark-colored hyphae, especially at the junction of the diseased and healthy parts. The color of the mycelium layer and the mycelium is red at the beginning, and then gradually deepens. In the later stage, the root cortex tissue is perishable, but the epidermis is still intact. After the autumn, in the clay layer or deep soil layer around the root of the disease, a hydatid block with a large and small shape can be seen. After the fruit tree is infected with purple feather disease, the growth of the aerial part is weak, the lobular leaves are yellow, and the branches are shortened or partially dried. In general, a diseased plant often takes several years to die.
Infected pathogen: Purple feather disease is a fungal disease. The pathogen is a genus of the fungus Basidiomycetes of the genus Mulberry, and the mycelium, rhizomes or sclerotia remain in the soil with the disease roots for wintering. When the conditions are appropriate, the mycelium is produced by the root fungus, which is directly invaded by the host.
Prevention and control methods to control the root disease of fruit trees, comprehensive prevention measures should be taken. The main technical points are:
1. Strictly choose the seedlings. Seedlings should be strictly inspected when they go out, and the diseased seedlings should be burned immediately. Before planting, the roots of the seedlings were immersed in 70% methyl thiophanate 500 times for 10 to 30 minutes for disinfection.
2. Strictly select anvil. When grafting fruit trees, choose disease-free rootstocks. It is best to use seedlings with strong disease resistance as rootstocks. Never use grafts with diseased rootstocks.
3. The diseased tree is bridged. When the root disease is severely affected, new roots can be bridged in the upper part of the roots of the early spring to restore the tree potential as soon as possible and reduce losses.
4. Strengthen fertilizer and water management. It can enhance the tree potential and improve disease resistance. Especially after the fruit trees enter the fruiting period, organic fertilizer should be added, pay attention to the application of phosphorus and potassium fertilizer to meet the normal growth needs of fruit trees. Reasonable pruning, control the amount of results, and timely control other pests and diseases to keep the tree strong.
5. Strictly treat the diseased soil. Fruit trees that are seriously ill and have died should be removed as soon as possible, and the roots of the disease should be removed after the diseased trees are removed, and the soil disinfection work should be done. Usually 40% formaldehyde 100 times solution or sodium pentachlorophenol 150 times solution can be watered in the diseased soil.
6. Pharmacy treatment of sick trees. When the orchard is found to have abnormal symptoms, it is necessary to dig the soil in time. Immediately after the disease is determined to be a disease, measures should be taken. Such as chalk disease, first completely scrape the root and neck lesions, and use the antibacterial agent "402" 500 times solution or 1% copper sulfate solution for wound disinfection, and then apply a protective agent; such as purple plume, white lines Feather disease, root disease, etc., should promptly remove the mold roots, and remove the roots of the disease out of the park and completely burned. At the same time, the soil around the root of the disease is dug out and replaced with a new soil that is disease-free. 250 to 500 times solution of sodium pentachlorophenol, or 500 to 1000 times solution of 70% methyl thiophanate solution, or 1:50 to 100 pentachloronitrobenzene. In addition, the effective agents for root rot are: carbendazim (Green Heng 1) 2000~3000 times liquid, carbendazim + thiram (1:9) 500~600 times liquid irrigation root, 40~50 per plant kg. When the rooting time is started in early spring and late summer, it is better to do it twice. Centering on the trunk, 3 to 5 radial grooves are excavated. After treatment, add manure or manure or urea to promote the recovery of the tree as soon as possible.
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