What are the control methods for crown gall disease in flowers?
Crown gall disease is also known as crown gall. In flowering cherry (Prunus serrulata) and Chinese rose (Rosa chinensis), crown gall mainly occurs at the root collar, but can also occur on the roots and aboveground parts. In the early stage of the disease, small nearly round tumor-like growths appear, which gradually enlarge and harden, with a rough, cracked surface; the color changes from light to dark brown or blackish brown, and the interior of the gall becomes lignified. The galls vary in size; large ones can be as big as a fist or larger, and their number ranges from a few to a dozen or more. Because the root system is damaged, diseased plants grow slowly, and in severe cases the entire plant dies. Besides harming flowering cherry and Chinese rose, this disease can also harm dahlia, lilac, begonia, geranium, rose, plum blossom (Prunus mume), as well as forest trees, fruit trees and more than 300 other plant species.
Disease development pattern
The pathogen and galls survive the winter in the epidermis and soil, and can survive in the soil for more than 1 year along with diseased tissue residues. The pathogen spreads through water flow, underground pests, grafting tools, farm implements, etc., and can be spread over long distances through the transport of infected seedlings and cuttings. After the pathogen invades through wounds, symptoms appear after several weeks or more than 1 year. The disease incidence is high in slightly alkaline, humid sandy loam; continuous cropping favors disease development, and more root wounds lead to more severe disease.
Control methods
① Strengthen quarantine. For diseased nursery stock, soak in 500-2000 ppm streptomycin solution for 30 minutes or in 1% copper sulfate solution for 5 minutes, rinse with clean water, then plant. ② In severely affected areas, implement crop rotation for more than 2 years, or disinfect the soil with chloropicrin before planting.
③ Cultivate carefully to avoid all kinds of wounds.
④ Replace cleft grafting with bud grafting; grafting tools can be disinfected with 0.5% potassium permanganate.
⑤ Severely diseased plants should be dug out and removed. For lightly diseased plants, drench with 402 at 300-400 times dilution, or after cutting out the galls, apply 500-2000 ppm streptomycin or 500-1000 ppm thiomycin or 5% ferrous sulfate to the wounds. It is also reported that applying methyl-iodine solution (50 parts methanol, 25 parts glacial acetic acid, 12 parts iodine flakes) to the galls has a therapeutic effect; Agrobacterium radiobacter strain 84 can be used for biological control.
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Control methods for crown gall disease in flowers
Crown gall disease is also known as crown gall. In flowering cherry (Prunus serrulata) and Chinese rose (Rosa chinensis), crown gall mainly occurs at the root collar, but can also occur on the roots and aboveground parts. In the early stage of the disease, small nearly round tumor-like growths appear, which gradually enlarge and harden, with a rough, cracked surface; the color changes from light to dark brown or blackish brown, and the interior of the gall becomes lignified. The galls vary in size; large ones can be as big as a fist or larger, and their number ranges from a few to a dozen or more. Because the root system is damaged, diseased plants grow slowly, and in severe cases the entire plant dies. Besides harming flowering cherry and Chinese rose, this disease can also harm dahlia, lilac, begonia, geranium, rose, plum blossom (Prunus mume), as well as forest trees, fruit trees and more than 300 other plant species.
Disease development pattern
The pathogen and galls survive the winter in the epidermis and soil, and can survive in the soil for more than 1 year along with diseased tissue residues. The pathogen spreads through water flow, underground pests, grafting tools, farm implements, etc., and can be spread over long distances through the transport of infected seedlings and cuttings. After the pathogen invades through wounds, symptoms appear after several weeks or more than 1 year. The disease incidence is high in slightly alkaline, humid sandy loam; continuous cropping favors disease development, and more root wounds lead to more severe disease.
Control methods
① Strengthen quarantine. For diseased nursery stock, soak in 500-2000 ppm streptomycin solution for 30 minutes or in 1% copper sulfate solution for 5 minutes, rinse with clean water, then plant.
② In severely affected areas, implement crop rotation for more than 2 years, or disinfect the soil with chloropicrin before planting.
③ Cultivate carefully to avoid all kinds of wounds.
④ Replace cleft grafting with bud grafting; grafting tools can be disinfected with 0.5% potassium permanganate.
⑤ Severely diseased plants should be dug out and removed. For lightly diseased plants, drench with 402 at 300-400 times dilution, or after cutting out the galls, apply 500-2000 ppm streptomycin or 500-1000 ppm thiomycin or 5% ferrous sulfate to the wounds. It is also reported that applying methyl-iodine solution (50 parts methanol, 25 parts glacial acetic acid, 12 parts iodine flakes) to the galls has a therapeutic effect; Agrobacterium radiobacter strain 84 can be used for biological control.