Big rise in bird cherry-oat aphid numbers

Bird cherry-oat aphid numbers continue to escalate this autumn, increasing the risk of barley yellow dwarf virus transmission to early-sown winter cereals, particularly in the south and west.

Latest data from Rothamsted Research’s nationwide network of 16 suction traps shows well over twice as many bird cherry-oat aphids were caught between 12th and 19th September than the previous week (see graph).

In all, 8,194 bird cherry-oat aphids were captured, a rise of 4,788 on the week. The total surpasses last year’s peak of 7,098, which was not reached until 4th October.

Dr Cathy Hooper of RAGT Seeds says: “As well as the massive and earlier increase in bird cherry-oat numbers, we are also seeing a very interesting trend in the proportion of cereal colonisers, the asexual clones that remain on cereals and produce nymphs that spread the disease within a field.

“Due to the mild winter last year and the warm, calm weather of last week, these asexual clones now make up 51% of the catch, compared to the 10-year average of 30.1%.”