25 September 1998

Cambs trial response is still cost-effective

DESPITE some of the lowest responses nationally, BASFs own strob trials in Cambs show cost benefits over conventional chemistry, and highlight variety and nitrogen interactions.

"Only Hereward failed to produce an economic return over fungicide cost," says BASF business development manager, John Peck. He is analysing data from over 1300 trial plots of wheat and barley grown at Upton and Gidding Farms, Alconbury, near Huntingdon.

Of 12 wheat varieties, Rialto alone responded better to a conventional triazole/morpholine programme of half rate Opus (epoxiconazole) and Tern (fenpropidin) at T1 followed by three quarter rate Opus and half rate Tern at T2 than half rate Landmark (kresoxim-methyl + epoxiconazole) at T1 and three quarters rate at T2 (see graph).

For barley, yield response was 0.1-1.1t/ha (0.04-0.4t/acre) more in the kresoxim programme, leading to an average increase in margin over fungicide cost of £33.63/ha (£13.61/acre) compared with conventional programmes. Fighter produced the greatest margin increase, at nearly £70/ha (£28/acre) from an extra 1.1t/ha, largely as conventional chemistry produced no yield response over untreated.

Angora and Melanie gave the greatest yield increase, at just over 2t/ha (0.8t/acre) over untreated.

"This was quite surprising. It reflects the high brown rust and net blotch pressure on the site," says Mr Peck. Conversely, low mildew this season saw much lower responses from Regina and Pastoral.

On average at Alconbury, for a comparable cost of £60-£70/ha, the kresoxim programme produced a 4% yield increase in wheat over conventional chemistry. Valued at £70, this means £28.26 extra on the bottom line. Riband, Equinox and Caxton all responded particularly well compared to conventional treatments, says Mr Peck .

Explaining extra yield response from kresoxim-methyl over conventional chemistry, and splitting varietal responses remains fraught with problems, Mr Peck maintaining it stems from more than just disease control.