Published on 28/07/2023
Their crops will be better off, too. Corteva AgriScience has spent the past four years gathering data in support of the new extensions.
The first is for Milestone herbicide, which is now registered for broad spectrum weed control in raphanobrassica.
And the second is for Korvetto tank mixed with T-MAX, which is now registered for control of amaranthus (redroot) in all forage brassicas except raphanobrassica.
Marketing manager Glen Surgenor says both label extensions will be a shot in the arm for growers’ weed control programmes, because in each case they deliver clear improvement over previous existing options.
“Up until now raphanobrassica has been excluded from the Milestone label, because it’s a relatively new variety in the market, and we didn’t have the necessary crop safety data. But we’ve now done the work to show when applied according to label instructions, it doesn’t cause any long-term effect on raphanobrassica crops.”
Better yet, it significantly broadens the weed spectrum for control in these crops, because it catches the likes of thistle and willow weed which are more suppressed than controlled by Radiate as an existing option.
“Radiate is good for fathen and nightshade, but with Milestone you get those others that can be a problem, including spurrey.”
Trials to establish recommended Milestone rates and timing were carried out in Waikato, Hawke’s Bay and Canterbury, three regions where raphanobrassica has taken off, not least for its performance under dry conditions.
“We basically started working on the new label extension about the time Milestone was launched, because we could see that growers would need better weed control options for what was going to be a very popular crop.”
If farmers have used Milestone before in other forage brassicas, however, Surgenor says it’s really important not to assume the use rate is the same for raphanobrassica.
“It’s lower, and we need to be really clear about that – 500 ml to 750 ml per ha for raphanobrassica, vs up to 1 litre per ha for other varieties.”
Turning to Korvetto, Surgenor says the prompt for pursuing this new label extension was recognition of how difficult it can be to get rid of amaranthus in forage brassicas. Tall, and fast growing, this widely distributed C4 weed can form large, aggressive plants and seriously compete with crops if it is not well controlled.
“Korvetto has some activity against it, but not enough that we could have guaranteed it so up until now amaranthus has not been on the label.”
So what’s made the difference now? - Adding 500 ml per ha of T-MAX to 1 L per ha of Korvetto.
“We’ve been looking at the T-MAX tank mix for a while, just to make absolutely certain that it would provide the level of control we felt comfortable with. Then when we tested it against the standards, such as Milestone, it turns out the Korvetto + T-MAX mix is even better at removing amaranthus than the options we already had available.”
In comparative trials throughout the North Island, this new combination consistently gave the best results, every time, Surgenor says.
“It’s great to be able to come up with a solution like this.”
Again, growers looking to take advantage of this need to be aware that the clover plant-back period for the combination is different to the plant-back for Korvetto alone, he stresses.
“It’s three months for Korvetto, and six months for Korvetto and T-MAX combined. We’re currently working on making that period shorter.”
For more detail contact your Corteva AgriScience territory sales manager.