1 March 2002

Strobilurin newcomers prove their worth in cereal trials

DONT judge the performance of strobilurins based on what happened last year, advises UAP technical director, Chris Bean.

With earlier drilling and higher disease risks this season, strobilurins will have a valuable role to play, he maintains.

UAP undertakes about 80 cereal trials every year and has up to three years experience with much of the chemistry reaching farms for the first time this spring. "This means we know where each new product sits within an integrated programme for a wide range of varieties, sowing dates and disease spectra," says Mr Bean.

Last year strobilurins benefits were lower than previously seen. The mean advantage over non-strob programmes in trials was only 0.45t/ha. This compares with the five-year average of 0.74t/ha.

But on more responsive varieties, even in what was a low disease pressure season, the right programme gave over 1t/ha more than triazole-based programmes, he notes.

Of the new strobs, he sees pyraclostrobin taking centre stage on wheat with picoxystrobin more useful on barley.

"As the strob in Opera, pyraclostrobin provides excellent disease control. It is on a par with that achieved from a well-balanced Twist/epoxiconazole mix. It also offers a significant improvement on the declining performance of Landmark."

Across four UAP trials on Riband and Consort in 2000, Opera (pyraclostrobin + epoxiconazole) at T1 and T2 outperformed Landmark (kresoxim-methyl + epoxiconazole) by 1.5t/ha and Amistar/Opus (azoxystrobin/epoxiconazole) by 0.8t/ha, he notes.

It was also 0.2t/ha ahead of a Twist (trifloxystrobin)/Opus tank mix. Similar responses have been seen on Napier and Savannah.

As well as controlling Septoria tritici, pyraclostrobin provides growers with another tool to target brown rust on the flag leaf – a disease Twist has had problems dealing with, says Mr Bean.

In trials on a highly rust-susceptible hybrid wheat, the new strob halved the disease on the flag leaf compared to Landmark and Twist. Only Amistar (azoxystrobin) offered similar control.

The new strobilurins will be particularly useful this season, Chris Bean believes.

Nitrogen use

Integrated agronomy trials in Wilts suggest pyraclostrobin can help crops make better use of nitrogen.

While Consort treated with Landmark or Opus programmes proved unable to show any benefit from nitrogen beyond 240kg/ha, an extra 80kg/ha applied to Opera-treated wheat pushed yield up a further 0.68t/ha.

"While Landmark appeared to plateau, the BASF strob gave a 5:1 return on the extra investment in nitrogen," says Mr Bean. "This is something well be looking to examine further in 2002."

Good potential in barley market

THE other new strob, Acanto (picoxystrobin), has potential as a T1 wheat product, but it is on barleys where Mr Bean sees it as a potential market leader.

"It has all the benefits of Amistar in barleys with the added advantage of good rhynchosporium activity."

In UAPs Aberdeenshire spring barley trials, disease control and yield from Acanto mixtures were as good as those from Opera (pyraclostrobin and epoxiconazole) and potentially more cost-effective, he says. Radius (cyproconazole + cyprodinil) and Caramba were the best mixer partners.

"We see it as an alternative to Amistar on barley to control rhynchosporium and net blotch." &#42