Farming Monthly National|June 2020
Bruchid beetles emerged from overwintering sites in mid- April and will be active in field bean crops during warm weather, particularly in winter beans that are flowering and forming pods. If you're growing field beans for human consumption, insecticides should be applied when the temperature threshold of two consecutive days at 20°C has been reached and around 50% of pods on bottom trusses are 2 cm long. Sign up for the Syngenta BruchidCast® forecasting service by going to www.syngenta.co.uk/bruchidcast.
The forecast predicts when the temperature threshold has been reached in different regions of the UK and indicates suitable conditions for spray applications. Growers should check that first pods have formed on the bottom trusses. To avoid risk to foraging bees spraying should be carried out very late in the evening or at night-time. Due to the warm temperature over the last week or two, spray thresholds may have been, or will be reached for winter beans.
Both pea aphids and black bean aphids have been reported in crops and in later drilled crops there may be an increased risk of damage caused by virus transmission.
The active substance thiacloprid is approved in combining peas, vining peas and field beans and will give good control of aphids if products are available. This is an option to control the earlier virus-transmitting aphids and may be used up to 2 times in a programme in alternation with non-neonicotinoid insecticides of a different mode of action. Do not use Biscaya in consecutive sprays. Check with processors before use.
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