Colex-D herbicide, which is an advanced 2,4-D formulation, is providing better options for agronomist Adrian Nelson at NU Rural, Quirindi on the New South Wales Liverpool Plains.
Mr Nelson said the region was very diverse in terms of cropping with canola, chickpeas, wheat, barley and faba beans grown in the winter and sorghum, corn, cotton, soybeans and mung beans in the summer.
He said as a result, the use of residual herbicides was limited because farmers were reluctant to lock in a rotation.
“They tend to play a little bit by ear depending on markets and when it rains. It might be too late for cotton, so they want to go to sorghum or mung beans. Residual herbicides are something we don't use a lot of because it locks people into particular rotations they don't want to be locked into."
The area has also been predominantly zero-till for the past 30 years and that has also been challenging in terms of the weed spectrum.
“We have glyphosate resistance, and we are also constantly chasing weeds such as fleabane and milk thistle. Fleabane is a surface germinator and, with rain, it's germinating constantly so it's a twelve-months-a-year job chasing it."
2,4-D herbicide is used to control a range of broadleaf weeds, including milk thistle and fleabane.
“It's got a huge fit there,” Mr Nelson said. “We put a little bit out very strategically over summer, but most of it is used in the winter and early spring, trying to make sure that we've got clean fallows going into summer crops."
The challenge with using 2,4-D in the summer is its proximity to sensitive crops, such as cotton, where it has the potential to cause major damage with drift and volatility.
Mr Nelson said in the past they used a lot of Statesman herbicide from Corteva Agriscience as a low volatility 2,4-D option but have now moved to Colex-D.
“Statesman was a big product used in this area,” he said. “It was a really good product with a very low odour. Colex-D is very similar. It has low odour, it's a good product and Corteva always make good formulations that mix well and work well.
“Colex-D is every bit as good as other 2,4-D's and probably slightly better. It’s definitely a good product.”
The herbicide was widely tested at the nearby Corteva research facility, at Breeza, with farmers and agronomists able to see the Colex-D being demonstrated.
This included a spray applicator where the Colex-D formulation was applied through one boom and a generic 2,4-D formulation applied from the other.
The reduction in drift was a noticeable feature.
“We were regulars at the Breeza field site,” Mr Nelson said. “Our local Corteva rep, Jon Dadd likes to make sure we're always there. He's good at rounding up a crowd.
"They just showed us the efficacy that was equivalent to other 2,4-D's, the better odour and compatibility with other products. They do a good job there."
He said Colex-D was commonly mixed with 450 g/L glyphosate formulations in a fallow situation and it worked well.
“It's a good product and it certainly seems to have less drift and less odour and farmers definitely like it. We like it for those reasons. I think it's some of the more innovative farmers that like to use new products that they can see have a definite benefit.”
The lack of odour was also something commented on by farmers that used Colex-D.
“Low odour from Colex-D is not as offensive as some of the other formulations – some of them are really, really offensive,” Mr Nelson said. “Farmers like it from that perspective and are willing to pay a bit more for it. There's certainly a perception that it's more user-friendly.
“We’re also in closely settled areas. There are smaller farms and there are lots of houses and neighbours around, so the low odour is important.”
NU Rural runs a number of spray applicators and implements strategies to maximise the efficacy of herbicides and reduce the risk of drift.
“We’re very careful about applications, with the correct water rates, droplet sizes and nozzles and we're sticking to the labels and making sure that we're not losing product off the target,” Mr Nelson said.
“We are sticking to 15 or 20 kilometres per hour, try to keep the boom as low as we can and use extra coarse nozzles which usually do a pretty good job.
“Stewardship for 2,4-D, in particular, is very important. Obviously, the cotton industry is particularly sensitive to it. They'd love to see it disappear but it's a key tool in farming. We need it and we need to make sure we look after it."
