Early findings from the AHDB autumn wheat bulb fly (WBF) survey suggest 2017 is likely to be another relatively low-risk year for this pest.
Conducted by ADAS, the survey involves taking soil samples in September from 30 fields prone to WBF attack (split equally across sites located in the East and North of England) and calculating the number of wheat bulb fly eggs/m².
The first results (17 trials) from the 2017 survey, which included all results (15 trials) from the East, were published last week. Six further sites from the North have been added yesterday (20 September 2017).
The initial results suggest 2017 is likely to be a relatively low risk year, with a slightly higher risk in the North.
Seed treatment threshold recommendations are based on drilling date and WBF egg populations.
Early-sown winter wheat crops (before November) are unlikely to benefit from seed treatment, as they have more time to tiller and are better able to withstand WBF attack.
For late-sown winter wheat crops (November to December), seed treatments should be considered where WBF populations exceed 100 eggs/m2 (moderate risk).
For late-winter/spring-sown crops (January to March), seed treatments should be considered irrespective of the WBF population size.
The WBF survey provides an indication of the overall risk level. As in-field risk depends on numerous factors, growers are advised to read the AHDB Wheat Bulb Fly publication to calculate the need to treat crops.