24 March 2000

Third strobilurin has extra disease control activity

By Charles Abel

NEW strobilurin fungicide trifloxystrobin finally gained full approval late last week, offering cereal growers improved control of Septoria and rhynchosporium and bigger yield responses.

Trifloxystrobin represents the next generation of strobilurin fungicides, according to maker, Novartis, offering some curative activity from the group for the first time.

"Septoria control is often the best among the strobs, and rhynchosporium control in barley is unbeatable," says product manager Neil Waddingham. Mildew control is equivalent to a morpholine, adds Bill Clark of ADAS.

Available as Twist, a straight 125EC formulation this year, a formulated mix with cyproconazole is planned for next year, with an expected brand name of Sphere.

"As a straight it takes the compromise out of fungicide choice," Mr Waddingham says. His preferred mixture partners are epoxiconazole (Opus) for wheat or cyprodinil (Unix) for barley.

In trials a Twist/triazole mix typically outyielded an equivalent Amistar/triazole mix by 0.2t/ha and a kresoxim-methyl/triazole by 0.4t/ha, the company claims.

Across all trials a Twist/triazole mix outyielded Amistar/triazole 67% of the time and kresoxim-methyl/triazole 94% of the time.

Inherent fungicide activity offers greater dose flexibility, says technical support manager, Chris Rowsell. Trials looking at Septoria control show a half rate of Twist matches a 60% rate of Amistar, for example.

Although not systemic, redistribution through so-called mesostemic activity improves coverage both within a plant and between rows, claims Novartis. In trials last year unsprayed plants 0.5m from rows sprayed with Twist had 68% disease control, compared with 30% where Amistar (azoxystrobin) was used.

"That does not mean you can reduce rates or spray alternate tramlines, but it is does improve the confidence of using the product," says Mr Waddingham.

Although Twist carries a LERAP requirement, approved air inclusion nozzles can be used to reduce the requirement to 1m.

lAt £41/ha (£16.40/acre) for the 2 litres/ha full rate, on-farm cost will be slightly higher than Amistar and comparable with Landmark, Mr Waddingham says. But in practice dose rate flexibility for Twist and its triazole partner will mean equal or slightly lower cost, he adds. &#42

TWIST

&#8226 New strob trifloxystrobin.

&#8226 Use rate 2 litres/ha = £41/ha.

&#8226 Strong on Septoria, mildew and rhyncho.

&#8226 Good dose flexibility.

&#8226 Available for T1 timing.

&#8226 Supply not limited.

Just in time for the season! Proof that the long-awaited strobilurin fungicide Twist is more than a myth – Novartis John Evans and Lorna Baldwin with a pack of the new product, together with its hot-off-the-press approval certificate, freshly granted by PSD.