The results of the final disease assessment of the 2010/11 Defra winter oilseed rape survey have been published. Highlights include the lowest incidence of Sclerotinia since 1989. Levels of light leaf spot were also decreased but Phoma stem canker was more prevalent than in 2010

Stems and pods of twenty-five plants from each surveyed crop were assessed visually at pod ripening for symptoms of disease.

• The proportion of crops affected by phoma canker (96% crops affected) was higher than in 2010 (74% crops affected). Incidence within crops was also higher with 37% stems affected compared to 18% stems affected in 2010. This summer, the incidence of phoma canker was also higher than the long term mean (2000-2009) of 87% crops and 35% plants affected. The incidence of total phoma (phoma canker and phoma stem lesions), at 97% crops and 40% plants affected, was higher than last year when 83% crops and 21% plants were affected. The highest incidence of phoma canker occurred in the South West, South East and Eastern regions (all with 100% crops affected), and the region with the lowest incidence was the North (86% crops affected).

• Light leaf spot on the pods was recorded on 33% crops and 5% plants, this was markedly lower than last year (55% crops and 17% plants affected) and lower than the long-term mean (2000-2009) of 35% crops and 10% plants affected. On the stems, an incidence of 81% crops and 34% plants affected was also lower than in the previous year when 89% crops and 44% plants were affected. The incidence was, however, higher than the long-term mean of 58% crops and 22% plants affected. Light leaf spot was found in all regions of the survey, with the Eastern Region having the lowest incidence.

• Sclerotinia stem rot affected 5% crops and 0.7% plants. Although incidence of the disease was very similar to last year (when 6% crops and 0.7% plants were affected), it was the lowest incidence of Sclerotinia stem rot since 1989, when 3% crops were affected. The incidence this year was also notably lower than the long-term mean (2000-2009) of 23% crops and 3% plants affected. Sclerotinia stem rot was found in all regions, with the exception of the Midlands & West. The region with the highest incidence of the disease was the South West where 22% crops and 0.4% plants were affected.

For more information on the CropMonitor survey click here