New research puts herbicides to the test at Breeza on the Liverpool Plains

Underlying these developments is an enormous amount of research, not only assessing weed control effectiveness but also crop safety and any undesirable environmental consequences.

One highlight from a recent Corteva herbicide field day I attended at Breeza on the Liverpool Plains was Colex-D herbicide. It is an upgraded 2,4-D formulation with a vastly reduced risk of drift and off-target damage, even compared to current amine formulations, let alone compared to ester formulations.

Corteva describes Colex-D (often referred to as choline formulation) as "a next-generation patented technology with performance and efficacy of normal 2,4-D products, but with field-proven Drift Reduction Technology, near zero volatility and ultra-low odour".

Vapour losses (volatility) in detailed testing were 96 per cent less than ester and 87.5pc less than amine formulations, with the comparison of 20.7g/ha active ingredient loss from ester 680 (at a rate of 0.8L/ha), 9.8g/ha loss from amine (1.15L/ha) and the loss from Colex-D (1.8L/ha) was only 1.2g/ha.

These losses, Corteva researchers note, translate into quantities of product vaporising and moving off-site.

In addition, volatility losses from ester and amine formulations can last for many hours after application.

In contrast, losses from Colex-D formulation, while minimal, are short-lived. Colex-D formulation losses are also low when mixed with glyphosate, a common herbicide fallow use combination.

Colex-D formulation clearly will have a vital role as registrations continue to extend its use, especially in fallow sprays or in-crop use next to susceptible crops.

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Research has also proven excellent compatibility with a good range of other herbicides.

Other aspects of the Breeza field day were assessing various Corteva herbicide products with other herbicides and adjuvants to increase the range of weeds able to be targeted with a single application.

For example, Rexade, a relatively recently registered herbicide, is widely used for in-crop control in wheat (not durum varieties) and triticale for a good range of grass and broadleaf weeds.

Corteva is assessing if adding various products to Rexade can increase the control reliability of several broadleaf weeds as well as strengthen control against some of the difficult to control grass weeds.

Research not only assesses improved control but also rules out combinations where some mixtures lessen the control of other weeds or increase the risk of crop herbicide damage.

Fortunately for Rexade, Corteva is likely to increase suggested additional herbicide mixtures that increase weed spectrum control with little risk of adverse crop damage or reduced control of other targeted weeds.

Trezac, another relatively new Corteva herbicide, is used widely in cereals for the control of a number of broadleaf weeds.

It is compatible with several other herbicides to increase weed control spectrum for a range of broadleaf and grass weeds.

Research is assessing if compatible mixtures for recommendation can be extended.

Probably no part of the cropping industry is so based on solid science as weed control.

Most crop and fallow weed control involve a variety of weeds in any given situation.

Not only is the choice of product for effectiveness critical, but so are strategies to avoid weeds developing resistance to them.

Product choice and rate to use also depend very much on the stage of weed growth and environmental conditions like soil moisture, temperature and even aspects like soil type.

A part of the Breeza field day that especially interested many participants was Corteva's interest in finding a better range of herbicides for use in pastures, especially legumes.

There are some interesting options appearing.

This is a space many of us will watch carefully as the choice is commonly much lower for pastures than for crops.

Next week: Pasture and fodder crops for all-year feed supply.