Following a mild winter, adult bruchid beetle populations in beans are typically less problematic because when beetles remain active through a warm winter, but without adequate pollen food resources, there are lower numbers surviving through to the spring.
This is according to Syngenta insecticides technical manager, Dr Max Newbert who says: “Coupled with the reports of good establishment of winter bean crops, along with strong emergence of spring beans with few signs of weevil damage, there is the potential to justify controlling bruchid beetle and aiming for a human consumption premium.”
Whilst the BruchidCast advanced warning system has proven effective, Dr Newbert says trials have shown a big advantage in earlier, well-timed control of the adult population to reduce initial numbers.
“If bruchid are actively present in the crop as it reaches the susceptible first pod set on the lower trusses, apply a knockdown treatment with Hallmark Zeon (lambda-cyhalothrin) when temperatures reach above 15degC,” he says.
“That has been shown to positively reduce the amount of egg laying when the BruchidCast trigger point, of two consecutive days with a temperature in excess of 20degC is reached.”
This approach means a second application with thiacloprid could better target any remaining hatched larvae.