The much-anticipated Overwatch® Herbicide from Agricultural Sciences company FMC, is available this season for control of Ryegrass and a wide range of other weeds in Wheat, Barley and Canola.
FMC Technical Extension Specialist, Stephen Pettenon said Overwatch® Herbicide had been in trials and demonstration plots over several seasons and was proven to be robust across a wide range of conditions.
Importantly, it has activity on a wide range of weed species including many that are challenging WA agronomists and growers.
Overwatch® Herbicide is registered for the control of Annual ryegrass, Bifora, Hog weed/Wireweed, Lesser loosestrife, Silvergrass and Sowthistle. It also provides suppression of Barley grass, Bedstraw, Brome grass, Capeweed, Phalaris, Prickly lettuce, Wild oats and Wild radish.
Mr Pettenon said Overwatch® Herbicide had been showcased alongside industry standards and included in a range of tank mixes to help growers determine the best option for their weed spectrum.
With an alternative mode of action compared to other commercial broadacre herbicides, FMC’s new herbicide is an excellent option to use for resistance management.
“Overwatch® Herbicide is unique because the active ingredient is a Group Q, up until now we haven't had a Group Q that's available for use Wheat, Barley or Canola.”
“In areas where Overwatch® Herbicide has been applied, ARG emerges as bright magenta colour. That's a function of the carotenoid being removed and the light basically oxidising all the green tissue. It actually goes pink, then it goes white and then it withers and dies."
He said crops such as Canola, Wheat and Barley have the capacity to metabolise the product and grow through, whereas a wide range of weed species do not.
Overwatch® Herbicide was initially considered because of its activity on Ryegrass, Mr Pettenon explains. “Australian producers spend more dollars controlling that particular weed than all other weeds combined. We’re really struggling with Ryegrass in our intensive system and resistance is a big issue. Coming out with a new mode of action and a new option is great news for everyone.”
The half-life of the active ingredient in Overwatch® Herbicide is a lot longer than other products and has demonstrated excellent residual activity for up to 12 weeks. Mr Pettenon said later germinating Ryegrass in the inter-row continue to turn pink well into the season.
“Ryegrass is an amazing beast. It can come up over a wide germination window, and we've seen that in our trials. Most other products run out of puff early but with the Overwatch Herbicide®, you can see a late emerging weed showing symptoms, and then control. This is a real positive for the product."
He said the recommended application of Overwatch® Herbicide is via Incorporated By Sowing (IBS) with the seed placed sufficiently away from the herbicide.
“The mode of action of Overwatch® Herbicide does not affect any cell division or any cell metabolism like other modes of actions so the seeds that you put in the ground will come up and the vigour is very strong. If the seeding depth isn't right, or if you've got unplanned or unwanted furrow fill, then you will get uptake of the chemical by those plants.”
“This can be expressed by the loss of green tissue or bleaching on some of the leaves. When it occurs, the effect is transient and the plant recovers.
“A lot of work has been done monitoring how the crop recovers and how the crop yields. It is happening at a very early stage of the plant's development and the work that we've done suggests that there isn’t any effect on yield.”
Mr Pettenon said it was exciting that Overwatch herbicide was now available, and it was important to look after it for resistance management.
“New actives don’t come along very often so Integrated weed management in line with the six principles of Weed Smart are recommended.”
Stephen Pettenon inspecting the excellent efficacy of Overwatch® Herbicide at the Geraldton WA trial site.