A NEW herbicide active substance has been approved for use in GB and should provide some comfort for farmers hit by the scourge of black-grass and Italian ryegrass in their crops.

BASF has received approval for its new active, Luximo, and the product containing this active, Luxinum Plus, will provide a new mode of action against grass weeds, especially Britain’s most challenging arable weeds.

This achieves two important milestones, according to Rob Gladwin, BASF’s UK head of technical management for ag products: “Firstly, it is 21 years since the current market standard, flufenacet, was registered for use in the UK market as Crystal in 2001; and secondly, Luximo is the first wholly CRD-managed active substance approval gained by any manufacturer since crop protection regulation was repatriated following Brexit.”

Luximo is the brand name for cinmethylin, a soil residual active substance for grass and broad-leaved weed control in winter wheat, for application at pre- and early post-emergence timings.

“We know how important this will be for growers, given the march of resistant black-grass, both geographically and biologically,” he added. “It’s two years since the Institute of Zoology valued our annual economic loss from resistant black-grass at £0.4bn in lost gross profit, and certainly the situation has worsened since this calculation.”

This new mode of action is crucial, to combatting weeds because it works differently to existing chemistry and can work against resistant black-grass and Italian ryegrass biotypes.

Stuart Kevis, BASF’s herbicide business manager, has worked for 10 years on the development of Luximo and assessed thousands of greenhouse and field trials involving the active. He sees it not just as an alternative to flufenacet, but a replacement for it.

“When comparing pre-emergence applications of solo flufenacet and solo Luximo, 85% of 103 farmer-led and BASF black-grass trials conducted over four years, found Luximo was more effective than flufenacet, with a much more consistent range of performance,” said Mr Kevis. “The mean control from solo Luximo in those trials was 78%, compared with 58% from flufenacet.”

In greenhouse sensitivity tests, submitted as part of the product’s regulatory approval process, samples from 196 black-grass populations – including 40% of which were resistant to Atlantis (mesosulfuron + iodosulfuron) – showed no cross-resistance to the newcomer.

“What stands out to us is the consistency of the results. Luximo reliably outperformed flufenacet in the control of black-grass and more than halves seed return compared with flufenacet,” he added.

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Against Italian ryegrass, he said: “There is a similar uplift in performance over flufenacet, as seen against black-grass, so solo Luximo is at least 20% better. Early indications are that it performs well against difficult ryegrass populations, including those that might be resistant to flufenacet.

“It’s important to mention that whilst these results were achieved when using Luximo as a solo applied active, for trial purposes, the use of complementary partner products is vital for retaining the field performance of it for the long term.”

Product stewardship must be kept front of mind by growers and agronomists, he argued. “Now that we have this all-important herbicide active substance, we must do all that we can to protect it from diminishing field performance, which will mean that growers will need to maintain a firm focus on good cultural control, careful choice of tank-mix partners and applying the herbicide at the right time, in the best conditions and at the correct rates.”

Some other attributes will be welcomed, Mr Kevis suggested: “Dry autumn soils have long-been a challenge for good performance from pre-emergence actives, so what’s really heartening about Luximo is that it needs less moisture than the current market standards, which, in essence, will give growers more available spray days.”

Consistent with BASF’s drive to help farmers enhance their business sustainability, he pointed out that 'over 50% of the raw materials needed to develop Luximo are derived from natural and sustainable sources, including pine tree resin and paper manufacturing by-products.'

It will be available this autumn as Luxinum Plus, in combination with partner products which contain partner active substances, such as pendimethalin.