It is not too cold to apply blackgrass killer Atlantis this autumn – yet. But the clock is ticking after this week saw the first significant frosts of the winter, according to agronomists.

Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium) needs to be applied to actively growing weeds for optimum results, says TAG Consulting agronomist Andrew Blazey.

“This week’s frosts are a warning sign that growth will begin to slow down.”

But so far the frosts have not been severe enough to have any real effect, UAP’s Chris Bean believes.

“It has not been below -2C, and the frost has lifted off crops by 10am.

Things are growing so fast, they won’t stop overnight.”

Growers will probably be able to apply Atlantis for most of November where necessary, suggests Agrivice agronomist Brendan Butterworth.

“It is when you have four or five frosts in a row when you might have to give up for the winter.”

Relatively little Atlantis has gone on to date, according to ProCam’s David Ellerton.

“Most will go on from now on, providing we get the right weather.”

Fields with high populations or tillering blackgrass need treating as soon as possible, says Frontier Agriculture’s Bob Mills.

“You can’t leave it until spring where you’ve got a carpet.

It is probably better to get 95% control from going now, than ending up with 99% control [from a February application] but losing yield [from competition].”

His customers have just started putting Atlantis on where applicable, he says.

“I suspect this year more will be applied in the autumn than we’ve seen since it came on the market.”

But growers who have successfully used pre- or peri-emergence treatments may still wait until spring, he suggests.

“That is particularly the case where other grassweeds, such as brome or ryegrass, are expected to emerge later.

If you’re expecting brome, and use Atlantis now, you’ve pretty well burnt all your bridges [for control later].”

mike.abram@rbi.co.uk