Cereals 2009: New generation fungicides to step up yields

Two fungicides were the key technical innovations on show at Cereals 2009. Both have increased yields by up to 1t/ha in wheat over typical standard programmes in trials, and both could be available in time for next spring.

Bixafen from Bayer CropScience and isopyrazam from Syngenta are similar chemistry to boscalid, already available in Tracker, although Syngenta was at pains to emphasise that its active belonged to a unique sub-group of the carboxamide chemistry.

Both will need to be used as part of a programme; indeed bixafen will only be available in co-formulations.

But it is the yield claims that will most interest growers – both formulations promise a decent increase over current programmes.

Bayer’s wheat formulation, BAYF869 averaged an extra 0.5 to 0.6t/ha over Firefly (1.5 l/ha) and Comet + Opus (0.4 l/ha + 0.75 l/ha) respectively using the full label dose, explained the firm’s Alison Daniels. That was from T2 applications following a common T1 spray across seven independent trials. An 80% dose of BAYF869 added 0.3-0.4t/ha.

Similarly in three trials where a budget, premium or programme containing the new chemistry was applied across different varieties, the new chemistry applied at T1 and T2 in a four-spray programme, yielded 0.5t/ha more than the premium four-spray programme and 1.1t/ha more than the budget three-spray programme.

“The extra yield is coming from a combination of better septoria and rust control, and physiological effects,” she said.

Research trials suggested it was more curative than the best azoles, more protectant than chlorothalonil on septoria, and better on brown rust than the strobilurins, she claimed.

Some of the evidence for that claim was from ADAS’s inoculated septoria trials, where sprays were applied at different timings to test prothioconazole, epoxiconazole and BAYF869 effects against septoria at different stages of development.

Differences could clearly be seen between products in controlling latent (infections in plant but not showing visible symptoms) and visible septoria infections, with BAYF869 clearly more effective than either azole, Dr Daniels said.

The new chemistry was also much more persistent than current standards, she suggested. “In trials we’ve seen an extra two to three weeks protection.”

That would allow growers an extra buffer if spray timings were delayed because of weather, she suggested. “It could also allow you to not be concerned with using a T3 as foliar top-up, potentially allowing better timing for fusarium mycotoxin control.”

Bixafen would also be available for barley growers, in a formulation described by Dr Daniels as a “Fandango upgrade”. “It lifts rhynchosporium and net blotch control by about 10% and is more long-lasting. In six 2008 trials it gave an extra 0.2t/ha over Fandango from a GS31 application.”

Powerful protectant

Syngenta‘s isopyrazam (coded 520) also promises a chance to significantly improve yields.

In a trial using wheat variety Duxford a mix of 520 and epoxiconazole yielded 2.5t/ha more than epoxiconazole alone, the firm’s Rod Burke said. That corresponded with significantly better septoria control eight weeks after treatment.

In another trial it had given an extra 1.5t/ha from a two-spray programme of 520 + epoxiconazole compared with Opus + Bravo.

“It is outstanding against septoria and rusts,” Mr Burke said. Activity against the latter was shown by the fact that in 23 trials comparing it with epoxiconazole, 520 had come out ahead in the vast majority, he pointed out.

The key to its success could be found within its chemical structure, Mr Burke explained. “It belongs to the benz-pyrazole group. The pyrazole ring gives it its broad spectrum disease control, while the benzonorbonene ring makes it more potent against septoria and rusts because it helps it lock onto the fungus better.”

That also helped with providing durable, long-lasting protection. “It is the most powerful protectant product we’ve ever worked with,” he said.