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 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 havent 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.

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.