20 February 1998

Class performance to beat blackgrass

By Edward Long

IN its debut season 100,000ha (250,000 acres) of cereals were treated with Lexus Class, according to maker DuPont.

Based on two new active ingredients, flupyrsulfuron-methyl for residual activity and contact-acting carfentrazone-ethyl, the 60g/ha rate is claimed to give 10-15% better control of blackgrass than full-rate IPU.

The residual component takes care of grass-weeds (not wild oats) and volunteer rape, mayweed, chickweed, groundsel and cranesbill. The contact partner kills cleavers, speedwell, nettles and other weeds.

"Lexus looks good but it is still early days to assess performance," says Andrew Rumsey of Clopton-based Suffolk Crop Protection.

"But we have seen it in trials for three years. It looked to be at least as good as IPU for blackgrass control. It also seemed particularly useful against volunteer rape, a common weed in this area.

"It is not the complete answer to herbicide-resistant blackgrass. But it does offer contact as well as residual activity from a new herbicide group, providing the opportunity to ring the changes."

He has seen some yellowing in treated wheat. While common following IPU use, particularly in late drillings, it seems transitory.

Independent crop consultant Dave Nicholls is pleased with Lexus Classs performance on wheats in Herts, west Essex and south Cambs.

"It is doing a cracking job on broad-leaved weeds and has killed the bulk of blackgrass. But I reserve judgement until late February to see if it all goes off."

So does AICC member Richard Martin, who looks after heavy land farms in south Essex, Herts, Beds and Bucks. "In my patch Lexus has mostly been used on oats. But more time is needed before the its effectiveness can be fairly judged."

On farms with difficult-to-control blackgrass it will need to be backed up with pre-drilling glyphosate (Roundup) and pre-emergence tri-allate (Avadex) used as part of his programme, he advises.

The new herbicide does not de-wax leaves so could be safer to use than IPU in frosty weather, he adds.