As featured in Arable Farming Magazine
Grass-weed herbicide waiting in the wings
by Arable Farming October 2020 issue
Anew herbicide aimed at tackling grass-weeds is planned for launch in autumn next year, subject to regulatory approval. Already available to growers in Australia, the active Luximo is a pre-emergence with a new mode of action and, according to manufacturer BASF, there is no known resistance to it.
Anew herbicide aimed at tackling grass-weeds is planned for launch in autumn next year, subject to regulatory approval.
Already available to growers in Australia, the active Luximo is a pre-emergence with a new mode of action and, according to manufacturer BASF, there is no known resistance to it.
In Australia the most problematic grass-weed is ryegrass, although a different species from the Italian ryegrass weed (lolium multiflorum) found in the UK.
Speaking at a BASF webinar covering grass-weed challenges, Lauren Merchant, BASF area sales manager, New South Wales, Australia, said: “One-quarter of a
million hectares of wheat has been treated [with Luximo] in all the major cereal growing regions and has shown consistent results and given a good level of control.
“It has performed extremely well, offering up to 12 weeks’ residual control.”
While black-grass remains the most problematic grass-weed in the UK, there are increasing concerns about herbicide-resistant Italian ryegrass, explained John Cussans, weed biology specialist at NIAB.
Tolerance
“I am hearing more and more about how black-grass is being effectively managed, but now we are seeing other weeds,” he says.
“With Italian ryegrass we are beginning to see increasing tolerance to pre-ems. While there may be a slip in sensitivity in black-grass, with some Italian ryegrass populations we are getting no control from flufenacet at all which is a really worrying trend.”
ALS resistance is appearing in meadow and rye brome populations.
Even in wild oats –where there are relatively low numbers of cases of ACCase and ALS resistance – resistance could increase, according to Mr Cussans.
“It is about monitoring and vigilance. Rotations are changing, cultivations are changing. It is about monitoring where weed populations are on-farm, what is expanding and what is less of a problem,” he says.
Intervention
“If you are seeing individual or patches of new weeds or weeds you haven’t seen before in different crops, opt for early intervention – particularly with Italian ryegrass. You can achieve a lot by pulling out the first few plants.
“Once there are large populations, managing multiple herbicide-resistant Italian ryegrasses in the UK will become an uncomfortable reality.
The practical management of Italian ryegrass could be more significant than managing black-grass.”
In the field Tom Reynolds, Pent Farm, Kent
Tom Reynolds manages 200 hectares with his uncle. Mainly arable the farm has a range of soil types, mostly heavy clays.
They also run a contracting business carrying out arable operations for other local farms.
He has changed his farming system in order to combat black-grass, but is concerned at the prospect of herbicideresistant ryegrass.
“Six to seven years ago, black-grass became a problem – some fields were overrun with it,” says Mr Reynolds.
“We decided that grass grows well here, so began growing grass seed, combining with a stripper header.”
Species grown include red fescue for amenity purposes, hybrid and Italian ryegrass.
Rotation
“After two years of grass, we put land into a legume such as winter beans, then have two years of wheats or barleys, mainly for seed, before going back to grass,” he says.
“It has been a good rotation for cleaning fields of black-grass.
“Locally, a lot of farms have got a lot better at managing black-grass, whether through doing what we are doing, or growing more spring crops.
“If ryegrass becomes a problem, it will make my rotation very difficult.
“If people think black-grass is a problem, ryegrass will be a lot worse. We will need a no nonsense, zero tolerance approach.”
A couple of fields Mr Reynolds provides agronomy services for have ryegrass problems and he says regular cutting for silage is being used to control it.
