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Carrot cavity spot

Cavity spot is a major disease of carrots in the UK which is caused mainly by the soilborne oomycete plant pathogen Pythium violae as well occasionally by other sepcies such as P. sulcatum and P. intermedium. Despite being soilborne, control of cavity spot relies on the application of foliar fungicides but levels of control can vary and enhanced degradation may also occur in some soils. Long rotations between carrot crops are recommended but not always possible. New strategies for cavity spot control are therefore required.

Although P. violae has been studied extensively at times in the past, progress has always been hampered by the lack of effective procedures for detection and quantification of the pathogen in soil. Molecular tools including specific DNA-based tests for P. violae have enabled a preliminary understanding of pathogen dynamics in soil and the effect of some abiotic and biotic factors. However, there are still fundamental gaps in our knowledge concerning the epidemiology of P. violae and how it interacts with its environment and hosts. Effective tools and methodologies for P. violae research are also lacking, including a reliable, realistic and reproducible artificial inoculation system which would allow the infection strategy of the the pathogen to be further investigated as well as different control methods.

At Warwick, two HDC projects are addressing the understanding and control of P. violae, the first of which is investigating the potential of biofumigants and other green manures to suppress the pathogen in field experiments. The second is a PhD studentship being carried out by Kat Hayles, who will be investigating the diversity of Pythium species causing cavity spot, aspects of their epidemiology, and the role of the microbial community in general in promoting / suppressing the disease.

Research Areas
  • Development of PCR-based diagnostics and tools for P. violae and other species including molecular characterisation and population structure.
  • Epidemiology of P. violae including effect of environmental factors, infection strategy and interaction with the microbial community.
  • Biofumigation for control of cavity spot disease.

Research Projects

cavity spot

mustard biofumigant

flailed mustard