Scottish growers have new ally in fight against problem weeds – The Scottish Farmer

It’s not often a new herbicide gains approval in today’s regulatory climate, so it’s very welcome news that a new weed control weapon is in the armoury this autumn. The Scottish Farmer looks at its capabilities

A new cereal herbicide formulation has shown strong performance on weed species common to Scotland’s arable areas, including annual meadow grasses and a wide range of broad- leaved weeds.

Its broad-spectrum activity and approvals in winter wheat and winter barley will make Fundatis a good fit in the North and take pressure off ALS-inhibitor herbicides relied upon to meet these challenges, according to ADAS principal weed scientist, John Cussans.

Approved in July, the product contains two active substances new to Great Britain.

Isoflex active – the trade name for bixlozone – is a HRAC Group 13 herbicide from the isoxazolidinone family with a new mode of action for cereals which inhibits carotenoid biosynthesis.

Its partner beflubutamid is from the same herbicide family as diflufenican, or ‘DFF’, (Group 12).

The weed science team at ADAS carried out annual meadow grass trials with Fundatis last year in winter wheat and saw excellent early assessment scores suggesting >95% control.

“In Scottish arable systems, and to some extent along the Welsh border, we worry about annual meadow grass, as we are over-reliant on ALS options for control,” says John.

“In annual meadow grass, while there are no confirmed cases of ALS resistance yet, the right time to worry about resistance is before we get it, so it’s great to have something new in the mix that’s contributing to control and reducing selection pressure on other herbicide groups,” he explains.

But resistance is also a concern for some broad-leaved weed species in Scotland.

Populations of chickweed and mayweed were confirmed as insensitive to ALS-inhibitor herbicides, such as the sulfonylurea group, some time ago. John says there’s also a suspicion that resistant poppies are present, and we are seeing groundsel populations with a range of sensitivity to the commonly used SU herbicides becoming much tougher to kill.

Part of the reason is series of residual herbicide losses, which has narrowed the broad-leaved weed control spectrum growers get from pre- or early post-emergence mixtures, largely based around flufenacet, and more recently cinmethylin.

In turn, this has led to greater reliance on SU herbicides, typically applied in the spring when optimum timing relative to the size of broad-leaved weeds is difficult to achieve.

He sees Fundatis used at pre- or early post-emergence in winter wheat, or pre- emergence in winter barley, as adding real value by taking the pressure off these tidy-up sprays.

“Often, you’ll get some later germination of broad-leaved weeds, but that good control of meadow grass, speedwell, chickweed, and groundsel means in some years you might not need a spring application at all.”

South of the Scottish Borders and down the country, more aggressive grassweed problems – blackgrass and Italian ryegrass – are become increasingly common. FMC’s commercial technical manager for Scotland and Northern England, Antonia Walker, says Fundatis will also play an important role in IPM programmes aimed at these weeds.

She says that, in trials, a solo application of Fundatis achieved 66% control of ryegrass and exceeded 54% control of blackgrass.

However, used in herbicide stacks, it can boost control and help herbicide programmes reach the elusive 95% control threshold needed to prevent the balance of the weed seed bank increasing.

Optimal seedbed preparation and application are key to ensuring minimal crop effect and maximising weed control with this new product.

Antonia advises good seedbed conditions are the first consideration with seed being covered with at least 2.5cm of settled soil.

“In cloddy, loose seedbeds, or where seed slots haven’t been closed adequately, some consolidation is advised before application of Fundatis, or any soil-applied herbicide product.” She adds that best timing is immediately after sowing when soils are moist, and optimal control will be achieved by applying before weeds reach BBCH11.

“Fundatis users will soon be able to access an online training module, which provides information needed for safe and effective application this autumn and beyond.”

Mike Jones farms 400ha near Chester, and his business is diverse – he has some 1200 store beef cattle, produces and mills his own wheat in a historic water mill, and grows barley, maize, and rotational ryegrass leys for his cattle.

Over the years, he has seen blackgrass become a concern, and more recently was caught off-guard by herbicide-resistant Italian ryegrass, which spread rapidly across the farm.

Guided by his Hutchinsons agronomist Andy Roberts, they have managed to get on top of the blackgrass by utilising more forage maize and two-year grass leys to clean up problem fields.

With barley crops all being fed to the cattle, there is also the opportunity to whole crop fields where grassweed control isn’t satisfactory.

“Our preference is to take it to harvest, as we need the straw from our barley, but having that flexibility has allowed us to take it off if it looks like seed return might be high,” says Mike.

Chemistry also plays an important role, and when offered the opportunity to host FMC herbicide trials three years ago, he jumped at the chance.

Trials have included Fundatis with different partners, and Mike says where it’s been used in the right combination, Italian ryegrass control has been impressive.

“There haven’t been many herbicides come through over the past few years, so it’s really encouraging, particularly in barley where options are limited,” he adds.

• Active substances: bixlozone + beflubutamid
• Crops: Winter wheat (pre- and early post-emergence, winter barley (pre-emergence only)
• Maximum individual dose: 1/ha
• Maximum total dose: 1L/ha
• Aquatic buffer zone: 5m