New adjuvant boosts grass herbicide’s uptake

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A popular Group 1 herbicide used in Prairie wheat and barley crops will now be sold with a new and "built-in" form of adjuvant that acts on its active ingredient, boosting the product’s uptake in grassy weeds.

The Canadian arm of ag chem and seed firm Syngenta said Monday its Group 1 pinoxaden product Axial will now be sold with a new adjuvant already added.

Axial’s label continues to cover it for control of wild oats, green foxtail, yellow foxtail, barnyard grass, volunteer oats, volunteer canary seed and proso millet in spring wheat and barley in the three Prairie provinces and B.C.’s Peace region.

Pinoxaden, a member of the "den" family of Group 1 graminicides, is absorbed by plant leaves and translocated to the growing points of leaves and stems.

However, while each of the three families in Group 1 ("fops," "dims" and "dens") inhibits the same enzyme and has the same site of action, each of the three families binds differently to the plant, the company said.

For example, Syngenta said, it’s found Axial to work on some wild oat populations that are "not controlled by other Group 1 graminicides."

Syngenta researchers, however, have now found their new adjuvant for Axial has "a unique action on pinoxaden," Ravi Ramachandran, Syngenta Canada’s manager for product chemistry and chemical services, said in a release.

The new adjuvant, he said, "increases (Axial’s) uptake versus standard crop oil concentrate (COC)- or methylated seed oil (MSO)-type adjuvants."

The name of the new adjuvant was not released Monday, nor available on any Axial product labels online.

The unnamed new adjuvant, Ramachandran added, marks "a significant step-change in adjuvant science and technology resulting in enhanced speed of activity for faster and more efficient grass control."

Axial 100EC’s most recent label, issued in 2010, covered the herbicide for control of those same weeds at 600 millilitres per hectare of Axial — that is, when applied with Syngenta’s adjuvant Adigor, a rapeseed-based MSO, at 700 ml/ha.

Adigor is currently listed as "co-packed" with Axial in its Axial FX, Axial iPak and Axial Megapallet packaging.

Syngenta’s other Axial product, Axial Xtreme, is a tank-mix of Axial with a Group 4 fluroxypyr herbicide.

Related story:
Weed tests show variety in Group 1 resistance, Nov. 28, 2008