2006/2007 SURVEY: SUMMER ASSESSMENT 2007

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 with phoma canker (92% crops affected) was similar to that in 2006 (94.5% crops affected). Incidence within crops was lower than in 2006. Thirty-eight percent stems were affected compared to 45.7% stems affected in 2006, which although lower than the previous year, is higher than the long-term mean of 23.8% stems affected. Incidence of total phoma (42.8% stems affected) remains similar to the long-term mean (43.4% stems affected).
  
  
• Historically the East and Midlands & West are the regions with the highest risk of phoma canker. In summer 2007, although levels of phoma canker and stem lesions were high in the East, the highest incidence was recorded in the South East.
  
  
• Levels of powdery mildew in 2007 were notably higher than in previous years. On the pods, 73.6% crops were affected compared to 24.7% crops in 2006 and a long-term mean of 10.6% crops affected. On the stems, levels were also higher with 74% crops and 37.9% stems affected. The highest levels of powdery mildew were recorded in the East and South East.
  
  
• Sclerotinia stem rot was particularly prevalent in 2007. Thirty-four percent of crops and 5.7% stems were affected. The proportion of stems affected is slightly higher than the incidence of 5.4% stems affected recorded in 1991 (which was considered an epidemic year for Sclerotinia stem rot), and was also the highest recorded since the survey began in 1987. The proportion of crops affected (34%) was the third highest incidence recorded since the survey began, higher incidences were recorded in 1991 (44.3% crops affected) and 2000 (37.2% crops affected). The highest incidence of Sclerotinia was recorded in the South West, which historically is the region with the highest risk.
  
  
• Light leaf spot on the pods was recorded at lower levels than in previous years. In 2007, 11% crops and 1% plants were affected, compared to 28.1% crops and 8.5% plants affected in 2006. Incidence on the stems, however was higher than last year with 56% crops and 17.5% stems affected compared to 45.5% crops and 14.7% stems affected in 2006. The highest incidence of light leaf spot on the stems was recorded in the North where 41.1% stems were affected. Historically the North of the country has the highest risk of light leaf spot.
  
  
• Alternaria pod spot was recorded on 23.6% of plants, which although higher than in 2006 (18.2% plants affected) is lower than the long-term mean of 32.1% plants affected. The Midlands & West were the regions with the lowest recorded incidence, which is consistent with previous years trends.
  
  
• Botrytis was recorded in 1.9% crops and 18.7% plants, which is higher than previous years.
  
  
• Downy mildew was not recorded in any crops surveyed.
  
  

Incidence of diseases on the pods - % plants affected

Incidence of diseases on the stems - % plants affected

Regional incidence of diseases on the pods - % plants affected

Regional incidence of diseases on the stems - % plants affected