Effects of Crotalaria juncea and C. spectabilis on hatching and population density of the soybean cyst nematode, Heterodera glycines (Tylenchida: Heteroderidae)

Abstract

In order to assess the efficacy of Crotalaria juncea and C. spectabilis as trap crops against the soybean cyst nematode, Heterodera glycines, rates of hatching of H. glycines eggs in the root leachate, penetration into Crotalaria roots by H. glycines juveniles and their development in the roots, and the effects of planting these Crotalaria species on population density of H. glycines in soil were investigated. The rates of hatching of H. glycines eggs in the root leachates from C. juncea and C. spectabilis were significantly greater than the rates in distilled water and in the leachates from non-host plants. Stimulation of hatching by C. juncea was significantly greater than that by C. spectabilis and similar to that by the host plant, kidney bean. The number of second-stage juveniles that penetrated Crotalaria roots was similar to the number that penetrated soybean roots, but most of the second-stage juveniles in Crotalaria roots did not develop to an advanced stage of growth. The population density of H. glycines in soil in which Crotalaria had been planted decreased significantly compared with that in fallow soil (no plants) in both pot and field plot tests. The effect of planting C. juncea on reduction in population of the nematode in soil was generally greater than that of C. spectabilis. From the results of these experiments, it was concluded that the use of Crotalaria, especially C. juncea, as a trap crop is a promising method for reducing the population density of H. glycines.