Current understanding of phoma stem canker and light leaf spot on oilseed rape in the UK

Oilseed rape is the third most important arable crop in the UK. Phoma stem cankerand light leaf spot are two economically important diseases of this crop. These twodiseases cause annual yield losses of winter oilseed rape worth > £100M, despite theuse of fungicides. Phoma stem canker is caused by two closely related fungalpathogens Leptosphaeria maculans and L. biglobosa, whereas light leaf spot is causedby the fungal pathogen Pyrenopeziza brassicae. Epidemics of both diseases areinitiated in autumn by ascospores released from crop debris from the previous croppingseason. However, phoma stem canker is a monocyclic disease, while light leaf spot isa polycyclic disease. Understanding the pathogen biology, disease epidemiology andhost resistance are essential for effective control of these two diseases. This minireview summarises current understanding of these two diseases in relation to pathogenbiology, disease epidemiology and host resistance.