Understanding interactions between Leptosphaeria maculans and L. biglobosa for improving control of phoma stem canker on oilseed rape in the UK

Phoma stem canker is an economically important disease of oilseed rape in the UK, including East Anglia. This disease can cause annual yield losses of winter oilseed rape worth > £80M, despite the use of fungicides. It is caused by two fungal pathogens Leptosphaeria maculans (Lm) and L. biglobosa (Lb). Lm is more damaging than Lb since Lm is often associated with damaging stem base cankers, whereas Lb is generally associated with superficial upper stem lesions. Lm can produce a secondary metabolite Sirodesmin PL which plays a role to enhance its pathogenicity, whereas Lb does not produce Sirodesmin PL. Results of our recent experiments showed that Lb can inhibit production of Sirodesmin by Lm, resulting in reduced infection by Lm. There is a need to understand interactions between Lm and Lb to improve control of this disease, which will make oilseed rape a more profitable crop for the UK’s farmers.
This PhD project aims to understand mechanisms of interactions between Lm and Lb for improving control of phoma stem canker on winter oilseed rape. To achieve the aim, there are five related objectives.
1). To investigate interactions between Lm and Lb during phoma leaf spot development.
2). To monitor the timing and abundance of Lm and Lb ascospore release.
3). To investigate effects of Lb on the production of the phytotoxin Sirodesmin PL by Lm.
4). To investigate effects of Lb on function of Lm effectors for effective use of host resistance.
5). To transfer new knowledge into new disease control strategies. New knowledge obtained from this work about interactions between the two phoma stem canker causal pathogens will be used to improve control strategies and delivered to growers through ADAS.