Surge in hot weather triggers Bruchid beetle warning

Adult Bruchid beetles have already been spotted in crops
Adult Bruchid beetles have already been spotted in crops

The welcome surge in hot sunny weather has triggered the unwelcome start of Bruchid beetle warnings – just as the winter bean crops are reaching the danger point of first truss set.

Despite the slow start to spring it has had a limited impact on species that typically invade later in the season, such as Bruchid.

These species are less affected by winter weather conditions, pointed out Dr Max Newbert, Syngenta Field Technical Specialist.

Adult Bruchid become more active in warm settled weather and, when there are two consecutive days above 20°C, farmers can expect the onset of egg laying on any existing pods, he warned.

Syngenta's early warning system, BruchidCast, has already predicted this occurring as the week goes by.

The warning system provides localised warnings of conditions that trigger beetle activity, to help growers to better time control treatments.

Danger period

The Processors and Growers Research Organisation (PGRO) qualifies the danger period being from when crops have 50% of pods on bottom trusses over two cm long.

Adult have already been spotted in crops, but farmers have been urged to check their crop for the presence of adult beetles before applications.

Dr Newbert pointed out that crops with no trusses present as yet do not need treating, but with the first warnings at such an early stage of the crop’s flowering and set, it could prove a long season for Bruchid activity.

Early egg laying gives longer for Bruchid beetles to mate and produce larger numbers of eggs and larvae, with greater levels of damage.

It comes on the back of an extremely bad year for bean damage in 2017, when a prolonged hot dry period in June saw sustained beetle activity.