Fast growing blackgrass, particularly in early drilled crops should encourage growers to bring forward Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium) treatment to this autumn, agronomists are suggesting.

“A lot more fields will warrant Atlantis use this autumn,” says UAP technical director Chris Bean.

“Blackgrass is coming through thick and fast, particularly in the more forward crops that got moisture at the right time.”

Blackgrass on those fields is already at 1-2 leaves, with some weeds even bigger than that, notes ProCam’s David Ellerton.

“It is growing at a fair old rate.

The seed matured in hot, dry conditions last summer, which meant it had low dormancy, and has emerged in a rush.

“That should enable growers to put on Atlantis this autumn, which is what we ideally want.”

Where no pre-emergence has been applied – and Dr Ellerton believes less has been applied this season – growers should try to go with a residual herbicide now and come back with Atlantis later in the autumn, he advises.

“That would avoid putting all the onus on Atlantis.”

But remember there has to be a six-week period following either IPU or chlorotoluron applications and an Atlantis treatment, warns Mr Bean.

“On some sites, particularly if blackgrass is developing quite readily it might be better to wait and put on Atlantis plus a residual.”

That is TAG director Jim Orson’s advice, too.

“It is a bit too warm for IPU at the moment anyway – you’re risking crop scorch. It is better to hold off until the conditions are right to apply Atlantis, particularly if you’ve already put on an effective pre-emergence.”

The biggest problem facing advisors might be persuading growers to put Atlantis on in the autumn, suggests TAG Consulting agronomist Andrew Blazey.

“I’m not sure growers will react to the blackgrass growing like stink by putting it on in the autumn.

They’ve seen it work too well in the spring.”

But Cambs grower Gavin Davies is already sold on autumn Atlantis.

“We had our best control last year, when some Atlantis went on in the autumn, with more in the spring.

But one lesson we learned was yield loss comes from earlier in the season.

We got our best yields from applying it in the autumn, so this season we’re aiming to do as much as possible in the autumn.”

mike.abram@rbi.co.uk