Black leg (Leptosphaeria maculans (Desm.) Ces. et de Not.) of rapeseed in Victoria: crop losses and factors which affect disease severity

Abstract

Surveys made of rapeseed crops in Victoria during 1971, 1972 and 1973 showed that black leg was widespread, but its severity depended on field location and sowing date. In crops sown on or adjacent to fields growing rapeseed in the previous year, black leg sometimes caused crop failure. In fields sown before August, the disease caused major yield losses, whereas in those sown later it caused only minor losses. There were no apparent differences in severity of infection between cultivars or districts. Infections which resulted in serious stem cankers were shown to occur before flowering.