BBRO can confirm that the emergency authorisation, granted by HSE, for the use of up to two applications of thiacloprid (Biscaya), has now come into force. This is in addition to the one application of flonicamid (Teppeki) already available for use on the UK crop. The emergency approval for Biscaya has been gained for the control of green wingless aphids, in particular, the peach-potato aphid (Myzus persicae), to limit and control the transmission of virus yellows.
The use of Biscaya is effective from 18th April and this approval is in place for 120 days from this date. Application(s) should be made via a ground boom sprayer in a minimum of 200 l/ha with a maximum individual dose of 0.4l/ha.
It is imperative that any application of thiacloprid (Biscaya) is applied at industry recognised aphid thresholds (see below and the latest BBRO 2019 Reference Book) and used in alternation with flonicamid (Teppeki), to minimise the risk of pest resistance developing.
The detailed emergency authorisation conditions can be found on the HSE and BBRO websites (https://bbro.co.uk/our-news-opinions/our-news/) and outlines the conditions of use, especially the buffer restriction zones, and environmental and operator protection measures required.
In summary BBRO emphasises:
• If numbers exceed the threshold for treatment of one green wingless aphid per four plants up until 12 leaf-stage (or one green wingless aphid per plant after this growth stage) then treatment will be justified.
• Repeat treatments will only be justified if the threshold is exceeded again at the appropriate growth stage.
• BBRO is now monitoring winged aphids via yellow water pan traps at 60 sites. This information will provide an early warning of pest pressure and to raise awareness to growers and agronomists to monitor crops for subsequent wingless aphid build-up. Remember the threshold for treatment is based on wingless green aphid numbers.
• Growers are advised to remove all root remnants, sugar beet cleaner loader spoil heaps etc. that could harbour aphids and virus, to minimise the risk of subsequent pest pressure and virus infection on the 2019 crop.
• Growers are encouraged to follow BBRO Advisory Bulletin updates and visit https://bbro.co.uk/on-farm/aphid-survey-map/ regularly for updates on aphid numbers and their virus levels.