Population dynamics of sugar-beet cyst nematode (Heterodera schachtii) on spring and winter oilseed rape crops

摘要

The influence of spring as well as winter oilseed rape on the change in population density of H. schachtii was investigated in microplot experiment in the years 2002-2005. The spring oilseed rape caused the increase of nematode population (P-f/P-i were 1.31-1.79), in contrast to winter oilseed rape where the population distinctly decreased (P-f/P-i were 0.49-0.59). No statistically important differences between winter oilseed rape crops and fallow were observed. Comparative observations of the life cycle were carried out in pot experiments outdoors. On spring oilseed rape only one generation was completed. The development of the second generation was interrupted because of crop harvesting. In winter oilseed rape J(3) and J(4) occurred in roots in the autumn where they probably did not over-winter, except of the years 2006-2007. In the spring there was a second emergence of larvae and adult females were observed in June and July. The development of the second generation was interrupted because of harvesting. In winter oilseed rape sown in the spring one generation was completed.