23 February 2024, Australia: Grain growers are taking up the opportunity to reduce grass weed populations on their properties with a new mode of action pulse crop herbicide that is relieving the pressure on traditional options and helping to clean-up paddocks for future crops.
The pre-emergent herbicide, Ultro®, is being targeted for use in premium pulse crops in high weed pressure paddocks in south-eastern Australia and in lupin crops in Western Australia. While it is achieving higher levels of grass control, it also offers wider benefits for entire cropping systems.
Increased early weed control also reduces root disease build-up for following seasons and allows improved crop competition against weeds. Excellent root pruning provided by the herbicide on the later remaining grasses assists the effectiveness of post-emergent selective herbicides.
Ultro-treated grass weeds can also remain greener for longer. In particularly high weed pressure paddocks requiring crop-topping, this allows these applications to be delayed, reducing the risk of crop damage from the operation and concern over grain maximum residue limits.
Featuring a new herbicide mode of action (Group 23), Ultro can be used in faba beans, lentils, field peas, chickpeas, vetch, broad beans as well as lupins across Australia, and also in winter fallow.
Alistair Crawford, Market Development Manager with ADAMA Australia in Victoria and Tasmania, said Ultro was used last season especially in high value lentil crops, which also generally provide reduced competition against weeds, as well as in some faba bean and field pea crops.
“It was used in problem weed paddocks mainly against ryegrass, and where there is some increasing resistance to glyphosate and clethodim, but it was also very effective against brome grass, which is more prominent in northern areas,” Alistair said.
“Ultro affects the whole plant and prunes roots, so it reduces weed numbers and can improve post-emergent grass weed control. This can reduce seedset for next year, which can help delay the development of herbicide resistance.”
Bevan Addison, Market Development Manager with ADAMA Australia in Western Australia, said many growers used Ultro in lupins as an alternative to propyzamide for control of ryegrass, but also for brome and barley grasses, which have become more problematic in recent times.
“The interest in Ultro for barley grass is growing, because grass selective sprays are not performing as well against various populations and it can reduce the pressure on these herbicides,’’ Bevan said.
He said where Roundup Ready canola and the associated use of glyphosate featured in programs, Ultro had proven particularly effective when included with paraquat in pre-plant knockdown applications.
“Once out of the canola phase, the use of paraquat with Ultro and metribuzin has been highly successful. Ultro is highly compatible with paraquat, and it improves grass control from the knockdown.”
At Merredin in WA, Elders Agronomist Keith Perry said not too long ago, growers were facing a brick wall with grass weed control in break crops, however the arrival of new mode of action herbicides like Ultro now had them much better positioned.
“Compared with propyzamide and simazine applications, it performs better in drier, more marginal conditions and it’s got some residual, which we haven’t had in the past with other post-emergent grass herbicides. We have been selecting for later emerging ryegrass with our Group 1 (A) herbicide applications,” Keith said.
“With a lot of sheep having gone out of the area, controlling grass weeds in pastures is no longer an option for many, so in cropping programs it’s lupins and canola. Lupins is a far better break crop for ryegrass control and Ultro has a good fit in that scenario.
“When looking over some lupins to determine grass selective sprays last season, Ultro was showing near enough to 100 per cent control. It will potentially take some of the pressure off Group 1 (A) selectives and, with its residual, there should also be less pressure on paraquat at crop-topping.”
He said the aim with lupin crops was to enhance the profitability of complete cropping programs and growers would not hesitate investing an extra $10 per hectare to achieve that goal.
At Roseworthy in South Australia, Elders Agronomist Craig Prior said Ultro had predominantly been used in faba bean and lentil crops mainly against ryegrass. This includied populations with some resistance to glyphosate and reduced sensitivity to lower application rates of clethodim.
“Ultro is slightly better and more consistent than propyzamide in more marginal moisture starts to seasons, like we had last year. The year before it also had to deal with 7-8 tonne (per hectare) stubbles, but it didn’t stop it from achieving consistent results,” Craig said.
He said it was an ideal option for high weed pressure paddocks and its residual helped improve control from post-emergent herbicides such as Encode® and clethodim.
“Anywhere Ultro has been used, the roots have been so severely pruned, they have almost just fallen over.”
Craig said the predominant four-year crop rotation in the region, comprising pulse, cereal and canola crops, also would allow for using Ultro in suitable rotation with propyzamide.
