29 January 1999

Split opinion on oats-in-potato virus control

SOWING strips of oats around or among seed potato fields could help cut virus infections, German work suggests, but a UK researcher is not convinced.

Trials in Lower Saxony, where the cereal aphid Rhopalosiphum padi is a significant bearer of potato virus Y, have found the bait plant technique particularly promising, according to Thomas Thieme of Bio-Test Labor.

Non-colonising R. padi, the bird/cherry aphid which also carries barley yellow dwarf virus, is hard to find in potato fields and not attracted to conventional yellow traps, so its impact may be under-estimated, says Dr Thieme. As well as being more attractive to the pest, the oats may also act as a mechanical barrier, he believes.

Further work is needed to determine the optimum size of the bait strips.

IACR-Rothamsteds Richard Harrington is unsure that such trap cropping would work in the UK. "It is of highly dubious value because there are so many other vectors of virus Y. One species I am particularly suspicious of is the leaf curling plum aphid. It often appears in large numbers just when the young crop is most susceptible in May and June."

Dr Harrington is also wary of trap planting as a technique. "There is some anxiety about it because it attracts pests in the first place in close proximity to the crop." &#42