Effects of fungicides on interactions between phoma stem canker pathogens, severity of epidemics and oilseed rape yield (collaborative project with ADAS and DuPont)

Thomas Sewell - University of Hertfordshire

Project summary

Phoma stem canker, a disease of oilseed rape (Brassica napus), is caused by sibling pathogens Leptosphaeria maculans and L. biglobosa. Both pathogens follow a monocylic disease cycle that causes leaf spotting in autumn/winter and stem cankers in spring/summer. Most severe cankers decrease transportation of water and nutrients.

Fungicides are important for phoma stem canker control. Triazole fungicides currently dominate the market, although reduced sensitivity in some plant pathogen species is a concern. Moreover, L. maculans and L. biglobosa have shown differing level of sensitivity to triazole fungicides. Therefore, increased knowledge on controlling phoma stem canker using non-triazole based fungicides is essential.

This project will use a combination of in vitro and in planta experiments designed to test the efficacy of certain fungicides on L. maculans and L. biglobosa growth. These experiments will also identify the effect fungicides have on interactions between the pathogens and their population structure. Furthermore, field trials will be established to investigate the efficacy of fungicides on phoma leaf spotting and phoma stem canker. Additionally, oilseed rape yield data from each plot will be gathered to help identify the benefit gained from applying certain fungicides at certain times. Conclusions will be made using all data sets collected from in vitro, in planta and in situ experiments.

This project will help refine fungicide application on crops using current commercially available fungicides. Knowledge on interactions between L. maculans and L. biglobosa in the presence of fungicides will help improve stewardship of those fungicides by targeting both phoma stem canker pathogens. Direct targeting of the most effective fungicide will increase longevity of the fungicides, reduce application volumes and save on farm costs.

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