Interactions between Leptosphaeria maculans, L. biglobosa and fungicides in oilseed rape

摘要

Phoma stem canker is a damaging disease of oilseed rape caused by a Leptosphaeria species complex, which consists of the related pathogen species L. maculans and L.biglobosa. Stem cankers caused by L. maculans are more damaging than those caused by L. biglobosa. The main fungicide used to control phoma stem canker in the UK is flusilazole, which is often applied in autumn during development of phoma leaf spots from wind-dispersed ascospores which land on the leaves. Interactions between L.maculans and L. biglobosa are being investigated. A winter oilseed rape field experiment to investigate effects of early and late applications of flusilazole on the disease was done in the 2005/06 growing season. In December, early-sprayed (29 October) plots had a lower incidence of phoma leaf spot than late-sprayed (29 November) plots. However, severity of phoma stem canker in July was decreased more and yield was increased more by the late spray thart the early spray in this experiment.