Published on 16/05/2022

The active ingredient in Questar is Inatreq, which is produced by fermenting a naturally occurring soil bacterium.
gives Questar an entirely new mode of action (MOA). It provides excellent Septoria and rust control when tank mixed with an appropriate fungicide. And because it has no cross resistance to existing MOAs, Questar is a significant advance in fungicide resistance management in wheat.
Corteva Agriscience market
ing manager Glen Surgenor says Questar will allow farmers and contractors to reduce their reliance on SDHI fungicides for cereal protection.

“Questar widens the options
for disease control in cereals. SDHIs are still going to be very important in the fight against resistance,” Glen says. “Without them we could see loss of efficacy of both Questar and the SDHIs, as well as other modes of action. For this reason, we strongly recommended that farmers only apply Questar once per season and always use it in combination with an effective tank mix partner. This is an important part of a responsible resistance management strategy for all cereal fungicides.”

The soil bacterium that is used
to produce Inatreq was first discovered at Osaka University in Japan. It 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 now used to control Septoria in wheat.

A big advantage Questar offers
is a flexible application window and it has a very favourable mammalian and environmental profile.
It can be used up to the T3
stage, although most applications will be at T1 or T2, which are the two most important fungicide timings for Septoria control.

Trials in New Zealand played
an important role in the development of Questar.  Since 2017 Corteva held 14 Questar field trials here and hundreds more overseas.
Glen says the series of trials
were complex and thorough. Additional demonstrations were run in 2021 – two in Canterbury and one in Hawke's Bay.

“Canterbury farmers who have
used Questar are enthusiastic about the new class of crop protection fungicide it provides and its control of Septoria,” he says. “Along with untreated control plots, the Questar trials compared disease control and crop safety with standard competitor fungicides. They considered different application rates, timings and tank mix partners.

Yields from wheat treated with Questar were consistently twice that of untreated, and equivalent to leading SDHI fungicides. This is a good indication of the very high level of Septoria control it achieves. The trials also helped us make sure Questar is compatible with insecticides, herbicides and plant growth regulators that may be used in wheat spray programmes.”

Major benefits of Questar:
  • Innovative resistance management tool with a different MOA against anew target site in Septoria.
  • Natural origin, derived from a soil microbe.
  • Residual protectant and curative activity.Flexible application timing up to T3.
  • Advanced formulation technology that improves retention and redistribution across plant surface and local plant mobility.
  • Favourable environmental and toxicological profile with low mammalian toxicity, low persistence in the environment, and few off target effects.

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