Extensive trials confirm Roundup Ultra®MAX with PLANTSHIELD® is a high performer against tough weed species

Trials led by trusted Australian scientists specialising in herbicide resistance testing showed the new Roundup Ultra^®MAX with PLANTSHIELD^® to be tough on problematic weed species, matching or outperforming other glyphosate herbicides commonly used in Australia.

This is the first time PLANTSHIELD has been combined with Roundup UltraMAX, a 570g/L high-load glyphosate formulation with Bayer’s proprietary surfactant system, delivering knockdown control of tough weeds.

PLANTSHIELD is a crop safener technology for specific in-crop use in cotton or canola, helping support crop safety in difficult conditions including drought, humidity.

Plant Science Consulting, based in Adelaide, conducted an outdoor pot trial over summer 2024/25 to compare the bioequivalence of Roundup UltraMAX with PLANTSHIELD to other commonly used glyphosate products.

The trial was led by Dr Sam Kleemann, who said growers can be confident the new product will perform on problematic weeds and under tough conditions.

“Based on the results, I think the new formulation of Roundup UltraMAX with PLANTSHIELD is going to give the same level or degree of activity as the old UltraMAX, but with the added benefit of PLANTSHIELD,” Dr Kleemann said.

“When you’re looking at a glyphosate formulation with consistency in terms of performance, I think Roundup UltraMAX with PLANTSHIELD will certainly do that.

“It looks like it’s going to give that same level of consistency that was observed with the old formulation, and it’ll give assurance to both growers and advisors that they’ll be using a good quality glyphosate product that’ll perform under most conditions.”

The replicated pot trial focused on four of Australia’s most problematic weed species: annual ryegrass, barnyard grass, brome grass, and sowthistle.

“The pot trial was done in a way where we’re trying to target a desired growth stage, which is applicable to that knockdown phase and timing,” Dr Kleemann said.

“We targeted the grass at that early tillering stage and at pre-elongation in the sowthistle.

“We found that Roundup UltraMAX with PLANTSHIELD was equivalent to a similar high-loaded product but was better than two other 450 g/L formulations being tested. This result was seen on both susceptible and glyphosate-resistant biotype.

“We found the same response with brome grass, which gives a fair bit of confidence that the product is working quite well.”

The trials also found that on sowthistle, Roundup UltraMAX with PLANTSHIELD was the strongest of the glyphosate products tested.

Dr Kleemann said the results were good news for Australian growers in the ongoing fight against hard-to-kill weeds.

“These species are all considered among the most problematic weeds in the country. Ryegrass is probably at the top of the podium in terms of its estimated yield loss and revenue impact to growers,” Dr Kleemann said.

“High-load formulations of glyphosate are quite beneficial in that they provide a higher level of active, per volume of product required in any given situation.

“It’s the surfactant package that really sets one glyphosate formulation apart from another.”

Dr Kleemann said it was exciting to be part of the development footprint for new products.

“It’s incredibly important that the likes of Bayer come to the fore, particularly as we’re seeing the growing evolution and development of herbicide resistance in Australia,” he said.

“To have a company that has the R&D capacity and infrastructure to undertake and tease out new actives is critically important to sustaining our current herbicide system.

“I’m quietly confident that between the work of independent organisations like ourselves and the likes of larger bodies like Bayer, the future’s pretty bright for Australian growers.”

For more information on Roundup Ultra^®MAX Herbicide with PLANTSHIELD^® and its effectiveness in trials, growers can contact their local Bayer representative.

Roundup Ultra^® and PLANTSHIELD^® are registered trademarks of the Bayer Group.