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Meeting on bean seed fly 9th December 2020

The management of bean seed fly has been causing considerable concern for growers over the last few years. The main reason for the concern is the loss, or imminent loss, of insecticidal seed treatments, since to date this method of applying insecticides has been the most effective. Several organisations are working on the problem and at a meeting for growers and agronomists on 9th December 2020, some of their recent activities were presented and discussed. The approaches investigated represent several components of a developing IPM strategy. Becky Howard (PGRO), Becca McGowan and Rosemary Collier (Warwick Crop Centre) and Max Newbert (Syngenta) gave presentations. Becca is a PhD student at Warwick Crop Centre funded jointly by the AHDB, PGRO and the University of Warwick.

Becky Howard talked about cultural approaches to reducing the size of the bean seed fly infestation, in particular by separating cultivation and sowing by a number of days. Although the results of her work in commercial pea crops have been variable, there is a clear indication that pressure is greatest when cultivation and sowing are undertaken on the same day, which is likely to be related to the flies’ attraction to freshly-cultivated soil. Both Becky and Becca McGowan talked about decision support tools; there was information on the use of baited traps and camera traps, trap colour (blue, white and purple are most effective and selective) and trap orientation (horizontal is most effective). Becca is working on the development of a day-degree forecast to predict the first period of fly activity in the spring, which coincides with the drilling periods for several crops. Although there was no discussion at the meeting about physical control (crop covers) or biological control (possibly with entomopathogenic nematodes), both approaches are being considered by growers. Finally, Max Newbert gave a summary of the position with regard to difficulties facing Force ST uses in crops with non-pelleted seeds and described the potential for the future development of two granule treatments by Syngenta, one based on Force (tefluthrin) and the other on Karate (lambda-cyhalothrin).

Becky Howard (PGRO) presentation

Becca McGowan and Rosemary Collier (Warwick Crop Centre)

Max Newbert (Syngenta)

Force MAPP11752 - response from CRD on 14th December 2020 to question from AHDB on use of treated seed:

Seed treated with Force ST M11752 may be marketed and used beyond 31 December 2021 in the UK.

Generally, unless an authorisation is withdrawn for safety reasons, treated seed can continue to be marketed and used after the final product use up date. A product label may require a ‘sow-by-date’ on the treated seed label but this is based on data showing how long the product remains efficacious and has nothing to do with the expiry of the product authorisation. Final sowing dates are not included on notices as the use of treated seed is not regulated through authorisations.