Up-to-date fungicide performance information for controlling light leaf spot is now available from HCGA. Results from 2012/13 and recent years show that, although tricky to control, fungicide treatments can prevent significant losses from the disease.

"At high-risk sites, autumn sprays are needed to keep the disease in check," says Dr Peter Gladders of ADAS. Light leaf spot is now the most important disease in winter oilseed rape and it is affecting all regions of the UK, including the south of England. "Following autumn decisions, all crops need careful monitoring in January and February, if any light leaf spot is found, deal with it promptly."

In the trials, there have been some differences between products and prothioconazole is the leading active. Control is likely to be improved by increasing the number of applications rather than by increasing dose.

"Looking at application rates, some of the trial sites have shown benefits from increasing dose above half rate. However, increases in disease control don’t always translate into significantly higher yields," explains Peter Gladders. There are also concerns that we are seeing reduced sensitivity to azole fungicides in certain parts of the UK. HGCA is aware of this challenge and will continue to monitor the situation in trials and in commercial crops.

The light leaf spot forecast from Rothamsted offers more positive news as it indicates a lower risk with forward crops being more vulnerable than later sowings. "Growers and agronomists need to remember that the forecast is based on pod infection, there was quite a lot of stem infection last harvest which may increase the risk in certain locations," adds Dr Gladders. Varieties grown in the south tend to have lower resistance ratings to those grown in the north and this needs to be factored in as well.

When choosing products, requirements for phoma activity and plant growth regulation activity should also be considered. Many crops are very advanced and growth regulation effects are, therefore, likely to be important this year.

A copy of the report is available at hgca.com/diseasecontrol. The light leaf spot forecast is available at rothamsted.ac.uk/light-leaf-spot-forecast