Look for aphids on emerging shoots as they could be walking onto the crop from volunteers and grasses and some aphids have already been flying around this spring. An aphicide should be considered if aphid colonies are found as they could be carrying barley yellow dwarf virus (BYDV) and potentially spreading it into the crop. Consider an aphicide of aphid colonies can be found on 50% of plants.
Note that if you are seeing ladybirds or hoverflies in crops then hold off on any aphicides as these specialist aphid predators will do a good job of mopping up aphids. Check crops again a few days later and if aphids are still on 50% of plants then consider the aphicide option.
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