Abstract
We established a four-year management system that decreased the population of Meloidogyne incognita to avoid injury due to continuous cropping of Japanese bunching onion by combination with soil disinfection and an antagonistic plant. In the first year, chemical treatments (chloropicrin + 1,3-dichloropropene, dazomet and oxamyl) were added to the soil before cultivation, the population of root-knot nematodes decreased after these treatments, resulting in an increased yield of Japanese bunching onion. Soil disinfections (chloropicrin + 1,3-dichloropropene and dazomet) had a higher effect on decreasing the population of root-knot nematodes. Positive effects of soil disinfection persisted for two years. In the third year, a leguminous antagonistic plant Crotalaria spectabilis was planted. There after, the population of root-knot nematodes greatly decreased, so the yield of Japanese bunching onion recovered the next year. The four years management system with soil disinfection and growth of an antagonistic plant crop was shown to be effective for reducing economic loss and the times of soil disinfection. This system should contribute to maintaining stable production of Japanese bunching onions.
