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Sclerotinia Disease

The fungus Sclerotinia sclerotiorum is an important plant pathogen causing Sclerotinia disease on many plant species. Important agricultural and horticultural crops such as oilseed rape, lettuce, carrot, vegetable brassicas, peas, beans and potatoes are all affected as well as wild plant hosts such as broad leaved weeds and wild flowers. The pathogen survives in soil as sclerotia (resting structures) 1-10 mm in diameter and when conditions are favourable, they germinate to produce small mushroom-like apothecia which eject ascospores into the air. These spores then infect plants causing rotting and plant death. The overall aim of our research is to understand the epidemiology, population structure and biology of the pathogen with the aim of improving disease management strategies.

Initial research at Warwick focused on epidemiology and disease forecasting, while more recently screening methods were developed which identified new sources of resistance in a Brassica napus diversity set. At the same time, the diversity and population structure of the pathogen was investigated in the UK for the first time. This led to the first report of the related species S. subarctica in the UK. A recently completed HDC PhD project further examined the incidence of S. subarctica with a focus on Scotland and Norway as well as the potential of biofumigation for disease control. A current PhD being carried out by Zofia Garajova will now be developing some of the early disease forecasting work further, with an overall aim of producing a regional risk system for Sclerotinia disease.

Research areas

  • Understanding the population structure, diversity and biology of S. sclerotiorum isolates from wild and crop hosts
  • Understanding the environmental conditions that affect key stages in the pathogen lifecycle and developing disease forecasting strategies through 1) predicting the production of apothecia/ascospores by germinating sclerotia and 2) identifying conditions for ascospore germination and infection
  • Development of robust and appropriate screening tests to identify resistance traits in crop plant diversity sets
  • Control of S. sclerotiorum using biofumigation

Research Projects


Selected publications

Clarkson JP, Fawcett L, Anthony SG, Young C (2014) A model for Sclerotinia sclerotiorum infection and disease development in lettuce, based on the effects of temperature, relative humidity and ascospore density. PLoS ONE 9, e94049.

Clarkson JP, Coventry E, Kitchen J, Whipps JM (2013) Population structure of Sclerotinia sclerotiorum in crop and wild hosts in the UK. Plant Pathology 62, 309–324.

Clarkson JP, Carter HE and Coventry E (2010) First report of Sclerotinia subarctica nom. prov. (Sclerotinia species 1) in the UK on Ranunculus acris. Plant Pathology 59, 1173.

Clarkson JP, Clewes E, Whipps JM, 2008. Diversity of Sclerotinia sclerotiorum from agricultural crops and meadow buttercup in the UK. Journal of Plant Pathology 90, S2.

Clarkson JP, Phelps K, Whipps JA, Young CS, Smith JA, Watling M, 2007. Forecasting Sclerotinia disease on lettuce: A predictive model for carpogenic germination of Sclerotinia sclerotiorum sclerotia. Phytopathology 97, 621-631.

Clarkson JP, Phelps K, Whipps JM, Young CS, Smith JA, Watling M, 2004. Forecasting Sclerotinia disease on lettuce: Toward developing a prediction model for carpogenic germination of sclerotia. Phytopathology 94, 268-279.

Young CS, Clarkson JP, Smith JA, Watling M, Phelps K, Whipps JM, 2004. Environmental conditions influencing Sclerotinia sclerotiorum infection and disease development in lettuce. Plant Pathology 53, 387-397.

Jones EE, Clarkson JP, Mead A, Whipps JM, 2004. Effect of inoculum type and timing of application of Coniothyrium minitans on Sclerotinia sclerotiorum: influence on apothecial production. Plant Pathology 53, 621-628.

Clarkson JP, Staveley J, Phelps K, Young CS, Whipps JM, 2003. Ascospore release and survival in Sclerotinia sclerotiorum. Mycological Research 107, 213-222.

Clarkson JP, Whipps JM, 2002. Control of sclerotial pathogens in horticulture. Pesticide Outlook 13, 97-101.

Contact: John Clarkson

sclerotinia on osr



sclerotinia apothecia