Symptoms and comprehensive control measures of plum root nodule disease

Symptoms and comprehensive control measures of plum root nodule disease

The fund project Sichuan Province 13th five-year Plan breeding Research Fund Project (2016NYZ0034); Sichuan 12th five-year Plan breeding Research Fund Project (2011NZ0098-8).

1 symptoms of disease

In the early stage of plum root nodule disease, the disease formed a gray-white tumor, the surface was rough, the internal tissue was soft, with the gradual increase of the tumor, the epidermis withered, turned brown to dark brown, the internal tissue was hard and Lignification, and the diameter of the tumor varied. If the disease tumor in the root neck or main root of the plant is large or more, the number of roots decreases, the ratio of the diameter of the diseased tumor to the diameter of the trunk is more than 1, the plant growth is weak and the yield decreases; if there are extra-large tumors on the root neck or root, the transport is blocked and the number of roots is extremely reduced. the tree is extremely weak and even dies [Jishan Huayao] [Jishan Huayao].

2 the route of transmission and the cause of disease

2.1 ways of transmission

Plum root nodule disease can be transmitted through a wide range of routes, such as Rain Water, wind, insects, transportation, personnel labor and so on. When introducing seedlings or rootstocks from the epidemic area, the nodule pathogen was brought into the epidemic area and spread in a short range through Rain Water, unreasonable irrigation, underground pests, labor and so on. The transportation and marketing of infected seedlings is the main way of long-distance transmission of root nodule bacteria.

2.2 causes of the disease

Plum root nodule disease is easy to occur in spring and summer, and there are many causes of plum root nodule disease. the main causes of plum root nodule disease are bacteria-carrying seedlings and unreasonable cultivation and management measures. First, seedlings carry bacteria. The seedlings carried bacteria when the seedlings or rootstocks were introduced, and they were not disinfected when they were planted. Second, improper cultivation and management measures. Improper management of soil fertilizer in the process of cultivation, partial application of chemical fertilizer in orchard, no or only a small amount of organic fertilizer, unreasonable drainage and irrigation in orchard, unreasonable moisture drainage in continuous overcast and rainy weather, and unreasonable irrigation in drought; improper cultivation and management measures such as mechanical damage caused by weeding and grafting in the process of work, failure to control underground pests in time, and other improper cultivation and management measures can easily lead to the occurrence of the disease.

3Comprehensive prevention and control measures

3.1 strict detection and disinfection of seedlings to control pathogens from the source

When normal seedlings are introduced from non-epidemic areas, because root nodule bacteria have a certain incubation period, they can not be observed only by naked eyes. All introduced rootstocks and seedlings must be disinfected before pseudo-planting and planting. Soak all the roots below the seedling interface or rootstock in 75% alcohol for 30 s, then soak 6-8 min in 0.1% liter mercury solution, rinse with clean water, or soak 5-7 min in K84 bacteria solution.

For self-propagated and self-bred seedlings, the plot without root nodule disease was selected as the nursery at first, and then the seeds were mixed with K84 during seedling sowing. When the seedlings come out of the nursery, the seedlings with nodules detected visually shall be resolutely removed and destroyed, and the available seedlings shall be soaked with K84 solution, the treatment method is the same as above.

3.2 rational cultivation to create environmental conditions that are not conducive to the reproduction and spread of root nodule pathogens.

3.2.1 establish a scientific garden. The incidence of root nodule disease is serious in the plots with heavy soil viscosity and poor drainage.

3.2.2 Scientific fertilization. Reduce the amount of chemical fertilizer applied in plum orchard and increase the application of organic fertilizer. Alkaline soil is beneficial to the disease, while acidic soil is disadvantageous to the disease. Therefore, the alkaline soil plum orchard should apply more organic fertilizer and physiological acid fertilizer, and adjust the soil pH value to slightly acidic, which is not conducive to the reproduction of pathogens.

3.2.3 timely and rational drainage and irrigation. Rain Water and irrigation water are the main vectors for the transmission of root nodule bacteria. Li Yuan, especially Pingba Li Yuan, should be drained in time after heavy rain, and should be irrigated reasonably during drought, not "serial irrigation", so as to cut off the way of pathogen transmission through Rain Water and irrigation water.

3.2.4 Scientific work to control underground pests in time. When ploughing and weeding, try to avoid causing wounds on the root neck; when breeding and high grafting, pay attention to protect the marriage interface, and disinfect the tools with 75% alcohol to avoid aggravating the disease caused by agricultural operations. Underground pests such as grub and mole cricket can cause damage to the root system of plum trees and lead to nodule pathogen infection, so it is necessary to control underground pests in time to reduce the occurrence of root nodule disease.

3.2.5 timely prevention and treatment of diseased plants. It was found that the tumor at the root neck or marriage interface should be removed in time, and the wound should be sterilized with 5 °B é stone sulfur mixture, K84 bacteria solution, agricultural streptomycin 400 × 500 solution or 3% gel suspended copper succinate 300 times solution. The removed tumors should be taken out of the orchard for centralized destruction.