Decreasing the risk of severe phoma stem canker caused by Leptosphaeria biglobosa on winter oilseed rape

Abstract: Air sampler data from four sites in the UK indicated that the pattern of ascospore release was similar between the sites, whereby ascospores of Leptosphaeria spp. were released from September 2015 to February 2016. However, the timing of first major ascospore and number of ascospores released differed between the four sites. Field trial results for effects of fungicides on control of phoma leaf spot severity indicated that both prothioconazole and penthiopyrad  picoxystrobin reduced the severity of L. maculans and L. biglobosa phoma leaf spots on some cultivars. There were differences in the effectiveness of the two fungicides in control of phoma leaf spotting between the cultivars. Prothioconazole reduced the severity of L. maculans phoma leaf spots on two cultivars and L. biglobosa phoma leaf spots on three cultivars. Penthiopyrad + picoxystrobin reduced the severity of both L. maculans and L. biglobosa phoma leaf spots on three cultivars.