23 October 1998

Fungicides prove their worth

THE value of fungicide protection on winter wheat, even with older less effective materials, was soundly demonstrated in Scottish Agron-omy Research trials last season.

In a detailed experiment testing a range of product combinations and timings at Whitekirk, East Lothian, untreated Consort produced only 6.5t/ha (2.6t/acre).

The best treatment nearly doubled output, and even a low-cost option based on sulphur and maneb delivered an extra 3.7t/ha (1.5t/acre) – almost 58% more than the unprotected crop.

Septoria nodorum pressure in 1997 was bad, notes senior agronomist Andrew Gilchrist. "Last season it was intense. None of the existing triazoles are very effective against it." It was mainly for that reason that the firm decided to investigate the newer Unix (cyprodinil) and strobilurin fungicides. "Limit-ed trials previously with Amistar as a head spray produced some fairly incredible results.

Top result at 12.9t/ha (5.2t/acre) last season came from a three-spray approach starting at first/second node (GS31-32) using Unix followed by two doses of Amistar (azoxystrobin) with a full rate of Opus (epoxiconazole) split between the first two treatments. "Unix certainly had an effect on stem-based diseases," he says.

Substituting 1litre/ha of Bravo (chlorothalonil) for the 0.5litres/ha of Opus at flag leaf in an otherwise identical programme trimmed that output by over 15%.

Second highest yield at 12.8t/ha (5.2t/acre) came from another three-spray programme using Corbel/Bravo (fenpropimorph/ chlorothalonil) at late tillering, substituting Mantra (kresoxim-methyl + epoxiconazole + fenpropimorph) for the flag leaf treatment, and omitting the ear wash.

Good results, up to 12t/ha (4.9t/acre), were also achieved with programmes using Landmark (kresoxim-methyl + epoxiconazole), notes Mr Gilchrist. &#42

FUNGICIDEFINDINGS

&#8226 58-100% wheat yield boost.

&#8226 3 and 4-spray options.

&#8226 Strobs outstanding.