Studies On Brassica Cyst Nematode Heterodera Cruciferae

Soil-sampling gave detectable levels of brassica cyst nematode in 70 out of 100 fields in a random survey of five intensive vegetable-growing parishes in Holland, Lincolnshire. Populations were great enough to cause measurable crop damage in 20% of the fields. In a damage assessment experiment on winter cauliflowers, yield of green produce and curds was closely correlated with initial density of brassica cyst nematode. For this species four methods of extracting cysts from soil samples were compared, and a reliable technique for recovering cysts, including those with egg-sacs, is described.