12 September 1997

Caution urged on BYDV test

AN INDEPENDENT researcher in Bristol has beaten the £450,000 HGCA-funded project to the market with a system for forecasting the risk of barley yellow dwarf virus to cereals.

However, workers involved with the HGCA-funded project question the validity of the independent model. They urge users to treat the BYDV Epidemic Simulation software developed by ex-IACR Long Ashton researcher David Kendall with caution.

Dr Kendall claims BES provides a reliable forecast of BYDV infection, provided there is little or no green-bridge carry-over of aphids and virus.

It warns of the need for, and timing of, insecticide sprays for aphid and virus control, using farm records and simple crop monitoring as the main inputs. The BES computer program costs £75.

However, aphid research has moved on considerably since the original model Dr Kendall was involved with, says Starcross-based Steve Tones. He is a collaborator in the HGCA-led BYDV forecasting project which includes ADAS, CSL, IACR and SAC, with field monitoring on 120 sites around the UK.

"The fundamental problem is that as far as I am aware the BES package has not been subjected to full, national validation."

That is vital given the severe financial consequences of getting BYDV control wrong, he says. "We just havent had the right conditions over the past two seasons to check forecasts." &#42