How to Prevent and Control Raspberry Crown Gall Disease? A Full Analysis of Practical Methods
In recent years, raspberries introduced from abroad have suffered fairly severe crown gall disease during cultivation.
Crown gall disease occurs mainly at the root crown, and sometimes is also scattered on lateral roots and branch roots. The diseased part is initially milky white, smooth and soft, and later gradually turns brown to dark brown, with a hard texture, a rough surface, and an uneven, bumpy appearance. Small galls are just a slight swelling on the cortex, while large ones are as big as a chicken egg and irregular in shape. Affected plants are stunted in development, with smaller and yellowed leaves, dwarfed plants, smaller fruits, and reduced yield. Field surveys show that the incidence rate of diseased plants is 5.6%-10.5%, and in severely affected plots the incidence rate of diseased plants is 34.4%, with a general yield reduction of about 10%, and in more severely affected plots a yield reduction of more than 30%.
The pathogen of this disease overwinters in the cortex of the diseased part and can also overwinter in the soil, where it can survive for 1-2 years. The bacteria mainly invade through wounds. From invasion to the appearance of galling, it takes as little as a few weeks and as long as more than 1 year. The pathogen can spread with diseased plant residues and can also spread with rainwater and irrigation water. The transport of seedlings is the route by which this disease spreads over long distances. This disease is prone to occur in alkaline soil plots.
To control this disease, first, select healthy and robust seedlings and remove diseased seedlings. Second, strengthen fertilizer and water management. Raspberry is a shallow-rooted fruit tree, with roots mostly distributed in the top 20-40 cm of soil. While irrigating in drought and draining in waterlogging, special care must be taken to prevent soil water accumulation. Appropriately increase the application of acidic fertilizers such as ammonium sulfate and potassium sulfate to create an ecological environment unfavorable to the occurrence of the disease. Do not injure the roots during cultivation and fertilization, and promptly control underground pests. Third, after the disease occurs, thoroughly dig out the diseased plants, dispose of them centrally, and disinfect the soil near the diseased plants with 10%-20% agricultural streptomycin or 1% Bordeaux mixture. Fourth, chemical control. Drench the roots with 0.2% copper sulfate, 0.2%-0.5% agricultural streptomycin, etc., once every 10-15 days, for 2-3 consecutive times. Soaking seedlings in K84 bacterial suspension, or drenching the roots after the disease occurs, both have a certain control effect.