25 September 1998

Low input wheats are a rarity

WINTER wheats performing reasonably well with fewer fungicides are thin on the ground in ARC experience.

Four seasons of work comparing single- and three-spray programmes have identified relatively few varieties where the extra two sprays have little effect on yield.

"It is very difficult to nominate reduced input varieties," says Dr Carver. "But a few are getting close to being single spray types." Abbot and Drake, with yield responses of only 3% and 2.5% respectively to the extra treatments, are potential candidates, depending on fungicide and grain prices, he suggests.

"Before strobilurin fungicides came along we reckoned anything under 2-2.5% was probably not worth chasing. Now with the strobilurins and with grain at only £70/t it is probably more like 3.5%."

Not unexpectedly, of the more familiar varieties Riband, Consort and Brigadier all responded well in the past three seasons, yielding 13.5, 12.7 and 9.3% more from three sprays instead of one single T2 (mid May) treatment. And only seven of 29 trialled gave less than 5% extra.

Clearly disease pressure has a bearing, says Dr Carver. At Dunmow, Essex, this year, where pressure was low, the marginal benefit of spraying three times was much reduced. Indeed in some varieties, notably Abbot, yield was lower after the triple triazole programme.

"Our site at Wimborne, Dorset gave us a much better idea of which varieties can tolerate low inputs." There the lowest response to the extra sprays in the strobilurin-based programme was 5.7% (in Drake). Using three sprays instead of one on Riband boosted output by nearly a third.