Rapeseed rhizobia, also known as root swelling disease, is a soil-borne disease that mainly affects cruciferous crops such as rapeseed. The disease is caused by the bacterium Plasmodiophora brassicae and is most severe in cold, poorly drained acidic soils. The pathogen can survive in the soil for 10-15 years and spread through rain, irrigation, farming, etc.
The nodules formed in the roots after the onset of rhizobia are mainly distributed on the main root, and there are few lateral roots, and the nodules are relatively largeRoot-knot nematode disease, on the other hand, mainly forms a lot of nodular nodules on fine roots. The shape of the root nodules of root swelling disease is spinning, finger-shaped, irregular, etc.;The root nodules of root-knot nematodes are spherical or conical in shape and vary in size.
1) Survival and reproduction of pathogens in the soil: Rhizobia can survive in the soil for a long time, and can multiply and spread in the soil, so that the disease can spread between different plots.
2) Soil environment: In acidic soils and poorly drained environments, the occurrence of rhizobia is more serious.
3) Continuous cropping: Long-term planting of the same crop, especially cruciferous crops, will increase the number of pathogens in the soil and increase the risk of disease.
4) Root damage: transplanting, underground pests or nematodes will cause root damage, so that the sporangia are activated and the root system is infected.
The occurrence of rapeseed rhizobia has a serious impact on crop growth and yield, and the growth of diseased plants is stunted, which may eventually lead to death. Therefore, it is essential to prevent the occurrence of rapeseed rhizobia.
1) Choose disease-resistant varieties: Choosing rapeseed varieties that are resistant to rhizobia can reduce the risk of disease occurrence.
2) Optimize planting density: Reasonable control of planting density can reduce the number of pathogens in the soil and reduce the speed of disease spread.
3) Strengthen fertilizer and water management: Reasonable fertilization and irrigation can help improve the disease resistance of plants and reduce the chance of root damage.
4) Implement crop rotation: Through crop rotation, especially with non-cruciferous crops, the number of pathogens in the soil can be reduced and the occurrence of diseases can be reduced.
5) Seed disinfection: Use drugs to disinfect seeds to reduce the possibility of seeds carrying bacteria.
6) Soil treatment: Treat the soil with drugs before planting to kill the germs in the soil.
7) Timely prevention and control: once the diseased plant is found, it should be removed and destroyed immediately to avoid the spread of the disease.