TARGET SITE resistance to sulfonyl-urea herbicides could now be present in blackgrass, says weed expert Stephen Moss of  Rothamsted Research.

“We’ve found a field in Essex where we suspect target site resistance. It’s never had Atlantis, but has had Lexus and previously Finesse in the 80s.”

As yet the findings are un-proven in field conditions and the result is an isolated case, he notes.

“It’s only in localised parts of the field. Other areas show just 5% resistance, which also supports the idea that it is target site resistance, which we’d expect to be patchy.”

Populations tested from other locations don’t show the same high level of resistance, but it would be foolish to assume it’s a one-off, he warns.

Bayer Crop Science already has anti-resistance advice in place for Atlantis.

“Our strategy has to assume there is a target site resistance plant out there,” says the firm’s Gordon Anderson-Taylor.

“If it is confirmed as target site resistance, and we’re waiting for that finding, then it reinforces those strategies.”

“We’re constantly reinforcing the need for cultural controls, such as cultivation and rotation, and to integrate those measures as key elements in grass weed management.”

Bayer always recommends Atlantis should be used with a residual partner and as part of a robust programme, says Barrie Hunt, Atlantis product manager.

“The key element is product stewardship.”