Is Cirray encouraging resistance?

Cirray™ cereal herbicide is a unique combination of fenoxaprop (FOP) and pinoxaden (DEN), two Group 1 active ingredients (AIs). The question some farmers are asking is: Because the two AIs in Cirray are present at lower amounts than in their original herbicide formulations, does this mean I’m applying lower rates of these actives and therefore encouraging resistance to develop?

It’s a reasonable question that speaks to increased awareness and knowledge of weed resistance and how it develops, and it’s great that farmers are concerned about not adding to the problem when they choose a cereal herbicide.

The answer is two-fold, starting with realities of your field then getting into the nitty-gritty of AI loading. Here’s what you need to know.

If you have known Group 1 resistance, do not apply any Group 1 grass herbicide.

From 2017 to 2021, independent testing confirmed the presence of Group 1 resistance in 651 out of 691 fields.1 Further, 90.6% of samples taken from those confirmed fields had both FOP and DEN resistance. It’s highly likely, therefore, that if a weed population is resistant to FOP, it’s also resistant to DEN. The era of spraying Group 1 subgroups as a resistance fighting strategy is over. It is not good practice to spray any Group 1 herbicide on a known Group 1-resistant field, period.

If no Group 1 resistance is present in your field, Cirray is anexcellent option for grass weed control.

A herbicide’s ability to control weeds depends, in part, on AI loading. In other words, how strong is the dose? Both pinoxaden and fenoxaprop are AACase inhibitors with activity against wild oats and foxtails, among other grass weeds. In Cirray, pinoxaden is at 67% of the load found in Axial® herbicide, and fenoxaprop is at 43% of the load found in Puma® Advance herbicide which puts the AACase load of Cirray at 110% (wild oat rate) and 154% (foxtail rate). In short, if your field doesn’t have Group 1 resistance and you apply Cirray, you are at no higher risk of developing resistance than you are applying any other Group 1 herbicide because the AI loading of Cirray is sufficiently high to control the weeds.

If you have any questions about Cirray and weed resistance, please call your local Bayer representative or the Bayer help desk at 1-888-283-6847.

1 Bayer product inquiries: samples tested by Ag-Quest for resistance to FOPs, DENs, DIM, clethodim and Group 2 AIs.