WET seasons, combined with the delayed effects of losing key active ingredients, means some weed species in Scotland are on the up.

Regional support manager for Scotland for UPL UK, Geoff Hailstone, gives some advice in this special feature on how farmers can improve their weed control through the tactical use of post-em actives, such as ethofumesate.

“Black-grass is not yet the widespread problem that it is further south, but it is on the increase.

Thanks to milder, wetter seasons and greater pressure on chemical options, farmers are also having to tackle a whole range of other stubborn weeds.

Whether that’s overcoming annual meadow grass in winter cereals and now also the spring crop, or controlling mayweed without isoproturon, it’s a greater challenge than ever. And don't neglect the fact that cultural choices also have an impact – brome species have been encouraged by min-till and the increased sowing of winter cereals.

Using alternative modes of action will not only help to control these weeds, but will also minimise the risk of resistance developing. Ethofumesate (Xerton), belongs to the benzofuran chemical family and works by preventing lipid synthesis, limiting formation of a waxy cuticle and targeting cell division in the roots and/or emerging shoots of sensitive weeds.

Currently registered as a post-emergence spray in winter wheat, it offers long-lasting control of annual meadow grass and applied at 0.6 l/ha, it offers 250g of the active ingredient. Approval is also being sought for the pre-em timing, to allow further flexibility when used in stacks for the control of black-grass and sterile brome.

Black-grass, formerly a rare occurrence in Scotland has, sadly, become more common, with an increasing number of agronomists south of the Tay experiencing incidents of infestation.

With close to 100% control being required to avoid build-up, ethofumesate applied before the weed emerges could play a vital role and can still be post-emergence of the crop, thanks to a flufenacet-based pre-emergence ‘holding spray’.

Growers should also give themselves the best opportunity to achieve high levels of long-term black-grass control by using all cultural methods – crop rotations, ploughing, implementing stale seedbeds and delayed drilling. These practices will allow growers to maximise use of herbicides with different modes of action.

For sterile brome, trials have shown that as with blackgrass, ethofumesate is most effective when applied pre-emergence of the grassweed. Currently, this means using ethofumesate as a post-em top up to the residual stack, which will still be before the emergence of the brome.

However, should a pre-em application be approved for next year, adding ethofumesate to a pre-em stack alongside actives such as tri-allate and flufenacet will offer an increase in flexibility for the control of this difficult brome.

Ethofumesate’s ability to be tank mixed or sequenced with a range of actives makes it very flexible to use. Well-known for application in sugar beet, it also has good activity on broad-leaved weeds including chickweed – a weed of particular importance due to the prevalence of ALS-resistant populations in Scotland.

It's to be hoped that growers in Scotland can embrace ethofumesate’s many benefits when planning their winter wheat herbicide campaigns.'