The change to colder and wetter weather has stopped the flight of aphids into crops. Growers need to be concerned about aphids from the green-bridge as well as any flying aphids as potential vectors of BYDV. Emerging crops should be checked for the presence of aphid colonies; one or two aphids on a shoot are a low risk of spreading BYDV – it’s only when they start to multiply and form colonies that can spread to neighbouring plants that there is a need to consider an aphicide treatment. Unnecessary aphicide treatments increase the risk of resistance, especially in the grain aphid where there are pyrethroid-resistant populations present in Scotland. As we are limited to using pyrethroid aphicides only on autumn crops, we want to avoid exacerbating the problem so only use aphicides when aphid colonies are present.
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