Accept cookies?

Our websites use cookies to deliver services to you on the internet. We do not use these to store personal information about you. Selecting Yes or No will set a cookie to remember your choice for this website.

YES     NO

Close this window   |  More information about our use of cookies.

Very close up shot of wheat crop ears in field

Summer disease assessment

Winter Oilseed Rape Disease Survey: Summer 2016

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

This summer, 85% of crops were affected by phoma canker. This was a very similar proportion to last year when 84% crops were affected and levels within crops were the same as last year with 27% stems affected. Canker incidence this summer was also very similar to the long-term mean (2005-2014) of 87% crops and 28% stems affected. However, there was a higher proportion of crops affected by total phoma (phoma canker and phoma stem lesions) this year, with 91% crops affected compared with 85% crops affected last summer. Within crops, the total phoma incidence was also higher, with 39% stems affected compared with 28% stems affected in the summer of 2015. The total phoma incidence this summer was similar to the long-term mean of 93% crops and 34% stems affected. The highest incidence of phoma canker occurred in the East, where 94% crops were affected compared with the lowest incidence, which was in the Midlands & West, where 69% crops were affected.

Having reached unprecedented levels of incidence in 2012 and 2014, with estimated losses in excess of £140M, light leaf spot incidence in 2016 was again the highest incidence recorded on both the pods and stems since the survey began in 1987. On the pods, the disease affected 95% crops and 57% plants, which was markedly higher than both last year (77% crops and 23% plants affected) and the long-term mean (2005-2014) (47% crops and 16% plants affected). On the stems, light leaf spot was also recorded at the highest levels since the survey began. The disease incidence this summer (100% crops and 81% stems affected) was markedly higher than both last year (89% crops and 44% stems affected) and the long-term mean (72% crops and 36% stems affected). Light leaf spot was recorded on the stems of 100% crops in all regions of the survey, but within crops, the highest incidence was seen in the South East where 93% plants were affected and the lowest in the North, with 77% plants affected. On the pods, the incidence ranged from 100% crops affected in both the South East and the Midlands & West regions to 88% crops affected in the South West. Within these crops, the highest incidence of light leaf spot on the pods was in the South West (70% of plants affected) and the lowest in the North (43% plants affected).

Levels of powdery mildew on the pods were higher than last year, with 15% crops and 2% plants affected compared with 6% crops and 1% plants in 2015. The incidence of crops affected with powdery mildew on the pods this summer was however, lower than the long-term mean (2005-2014) of 25% crops and 8% plants affected. On the stems, 15% crops and 3% stems were affected with powdery mildew, this was lower than last year when 38% crops and 5% stems were affected and also lower than the long-term mean of 30% crops and 10% plants affected. The region with the highest incidence of powdery mildew on the stems was the South East, with 38% crops and 5% plants affected and the lowest was the South West, where it was not recorded on any stems in the survey. The South East was also the region with the highest incidence of powdery mildew on the pods (50% crops and 7% plants affected) and the Midlands & West had the lowest incidence (8% crops and 0.3% plants affected).

Sclerotinia stem rot affected 8% crops and 1% stems this summer, this was higher than the 1% crops and 0.04% stems affected last year but lower than the long-term mean (2005-2014) of 16% crops and 2% stems affected. The region with the highest incidence of Sclerotinia stem rot was the South West where 38% crops and 6% plants were affected - this was mostly due to three severely affected crops in this region. Sclerotinia stem rot was not recorded on any surveyed crops in the Midlands & West and South East regions. Sclerotinia disease on the pods affected 4% crops and 0.4% plants affected – higher than last year when 1.0% crops and 0.1% plants were affected, and also higher than the long-term mean of 0.1% crops and 0.04% plants affected. On the pods, the South West was the region with the highest incidence where 25% crops and 2% plants were affected.

Alternaria pod spot was recorded on 32% crops and 4% plants, a lower incidence than last year when 56% crops and 8% plants were affected, and also lower than the long-term mean (2005-2014) of 65% crops and 16% plants affected. On the stems, Alternaria affected 5% crops and 0.2% stems this year, which was higher than last year (4% crops and 1% stems) but lower than the long-term mean of 13% crops and 2% stems affected. Alternaria pod spot affected crops in all regions in the survey, with the South East having the highest incidence (50% crops and 11% plants affected) and the North with the lowest (19% crops and 1% stems affected). On the stems, the South East also had the highest incidence of Alternaria, with 13% crops and 1% plants affected and the region with the lowest incidence was the Midlands & West, where it was not recorded on any stems in the survey.

Botrytis on the pods was recorded at lower levels compared to both last year and the long-term mean (2005-2014). This summer, 57% crops and 11% plants were affected compared with 69% crops and 13% plants affected in 2015 and 73% crops and 22% plants affected in the long-term mean. On the stems, Botrytis affected 3% crops and 0.1% stems, which was the same as last year, but lower than the long-term mean of 15% crops and 2% stems affected. On the pods, Botrytis was recorded in all regions of the survey, with the South West having the highest incidence (88% crops and 24% plants affected) and the South East with the lowest (25% crops and 8% plants affected). On the stems, Botrytis was only recorded in the Midlands & West and South East regions, with the highest incidence being in the South East, with 13% crops and 1% stems affected.

Verticillium wilt was reported for the sixth year in the survey and was the lowest incidence of the disease seen so far. Three percent crops were found to be affected and within crops, 0.2% stems were affected by the disease. This was lower than in the previous year when 6% crops and 1% plants were affected. This summer, Verticillium wilt was only found in the East and Midlands & West regions in the survey, with the Midlands & West having the highest incidence with 8% crops and 0.3% stems affected.

Downy mildew was not recorded on either the stems or pods of any surveyed crop this year. The last time downy mildew was recorded on the stems in the survey was in 2009.

Incidence of diseases on the pods - % plants affected

Incidence of diseases on the stems - % plants affected * Please note – no long-term verticillium data available *

Regional incidence of diseases on the pods - % plants affected

Regional incidence of diseases on the stems - % plants affected