07/10/2024

Corteva Agriscience has delivered a new 2,4-D option with Colex-D®, a novel choline salt formulation designed with patented Drift Reduction Technology and near zero volatility to ensure optimal weed control and significantly reducing the risk of damage to sensitive crops nearby.

Launched in 2023, Colex-D was initially approved for the control of weeds in fallow and non-agricultural areas, but in April 2024 the APVMA approved the herbicide for use in pasture and cereal crops as well.

The use of 2,4-D products is becoming increasingly challenging due to spray drift and volatility concerns, but six trials over the past four years have shown no volatility from Colex-D when applied beside cotton, which is highly sensitive to 2,4-D vapour.

Corteva field scientist Greg Wells said Colex-D presented new chemistry that addressed both issues.

“The chemistry drastically changes the way Colex-D behaves and makes it very different to other 2,4-Ds on the market, the amine or ester versions, which may contain additives to their existing chemistry in an attempt to reduce physical spray drift or volatility. These additions, however, generally have little impact on the volatility of these products following application” Mr Wells said.

“Colex-D has a salt added to the side of the 2,4-D molecule which makes it much more stable in solution – it actually breaks apart then reassociates. So, in layman’s terms it is much more stable, both in solution and more importantly, when it’s applied to plant surfaces.

“Other products, when mixed with water, break up to become 2,4-D acid, which makes them somewhat volatile with the ability to move off soil or treated plant surfaces after application. Colex-D is much less likely to do that.”

A research paper on Corteva’s field trial results testing drift reduction and volatility will be shared at the coming Australasian Weeds Conference in Brisbane in August.

Mr Wells expected the recent addition of pastures and cereals to the Colex-D label would also significantly boost the use of the herbicide where these are grown in proximity to sensitive crops.

“Colex-D contains additional ingredients that drastically reduce the driftable portion of spray droplets. In testing, Colex-D reduced extremely fine, very fine and fine drops by 100%, 63% and 26% when compared to a commonly used 2,4-D amine formulation,” he said.

“Again, it’s the new chemistry that makes the difference, especially when considering volatilty. In practice in the field there’s been no movement from Colex-D treated soil. That’s very different to ester and also to amine-based formulations.

“It also has a very low odour, which is quite different to existing 2,4-D products and is much more user friendly. When mixing 2,4-D the smell is strong and can be problematic for users and for neighbours concerned about sensitive crops.”

To ensure best practice management in the use of Colex-D, a Compatibility Calculator is available on the Corteva Agriscience website, listing a summary of products and a yes/no response on mixing.

Mr Wells said comprehensive testing to inform the Compatibility Calculator aimed to determine whether tank mixes are physically compatible as well as compatible with Colex-D’s Drift Reduction Technology, to ensure that tank mixing doesn’t result in off-target drift.

“Generally, Colex-D has mixed with most things very well, but some of the new glyphosate formulations that have other adjuvants are not always compatible,” he said.

“The older 450 Glyphosate formulations are generally fine. The other issue to consider with mixing is when you put the chemicals together and spray out, does the partner product change the spray quality when combined with Colex-D?

“The Compatibility Calculator will tell you yes, it’s okay, or no, it’s made it more driftable. We’ve done a lot of testing in the background to support that.”

Greg Wells says while Colex-D costs more than its amine-based competitors, it provides a lot more technical benefits that others don’t.

“Some people opt for the cheaper alternative, but I think the time will come when people choose to, or are forced to, make a different decision due to restrictions or regulations on 2,4-D in the marketplace,” he said.

“Corteva is undergoing further work to continue to broaden the present label, and these updates should be available by early-to-mid next year for agronomists and resellers.”

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