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Take the strategic approach with fungicides this season

Published on 29/09/2023

“We’re starting to see a shift in Septoria sensitivity to existing chemistry so the industry needs to incorporate new modes of action into those programmes before full resistance develops, and good chemistry is lost,” says national marketing manager Glen Surgenor.
“SDHI’s (Group 7) have been a market stand
ard for the past decade, and we can’t afford to break them.”

He’s referring to ongoing Foundation for
Arable Research monitoring, supported by all major crop protection suppliers, which tracks the sensitivity of New Zealand Septoria strains to fungicides with different modes of action.

Most recent testing suggests small sensitivi
ty shifts in the SDHI fungicides, although they currently remain effective.

FAR data identify the biggest sensitivity
shifts are in DMI (Group 3) fungicides, including significant changes for epoxiconazole and prothioconazole.

Surgenor says the value of such monitor
ing lies in giving NZ growers early warning of what might be coming.

“Unlike in the United Kingdom, for example,
where they no longer have access to some SDHI technology because of resistance, we have time to protect what we have. But to do so, we can’t just keep doing the same thing we’ve always done.”

Cue Questar, with its unique active ingredi
ent Inatreq. This is the first member of a new class of cereal fungicides, the picolinamides (Group 21), which have a different target site to all other fungicides currently applied for Septoria control in wheat.
Questar is the first naturally derived fungi
cide brought to market by Corteva Agriscience; Inatreq is produced by fermentation of a naturally-occurring soil bacterium first discovered at Osaka University in Japan.

It’s been winning support since Corteva
launched it three years ago, but should be strategically integrated into more programmes as a critical circuit breaker to protect existing chemistry, Surgenor says.

It has no cross resistance to existing fungi
cides in the wheat market, and is highly efficacious, making it invaluable for resistance management strategies.

It’s also flexible in terms of application tim
ing – up to T3 – although most applications will be at T1 or T2 which are the most important fungicide timings for Septoria control. But again, it must also be used with care.

“We’re strongly recommending only one
Questar application per season, which will help protect Questar from the development of resistance, and also make the most of this new MOA in slowing resistance to other fungicide groups,” Surgenor says.

“We very much want to be part of a respon
sible resistance management strategy for all fungicides for Septoria and other cereal disease control.
Maintaining the efficacy of current fungicides
requires careful management, which includes using different modes of action like Questar, applying the correct rates at the right time and growing Septoria tolerant wheat.

Questar – key points

• Innovative resistance management tool – different MOA against a new target site in Septoria.
• Natural origin – derived from a soil
• Residual protectant, and curative ac
• Flexible application timing – up to T3
• Advanced formulation technology
– improved retention and redistribution across plant surface as well as local plant mobility.
• Favourable toxological profile – low
mammalian toxicity, low persistence in the environment.
For more information, contact your Corteva
Agriscience territory sales manager.

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