Now is the ideal time to spray winter wheat crops with an effective herbicide to knock out blackgrass and other problem grass weeds, NIAB TAG’s Ben Freer said.

Current soil temperatures favour Atlantis (mesosulfuron + idosulfuron) and Broadway Star (pyroxsulam + florasulam)/Broadway Sunrise (pyroxsulam and pendimethalin) to tackle blackgrass and sterile brome.

“We have perfect conditions for Atlantis,” said Mr Freer, regional technical agronomist at NIAB TAG.

“The blackgrass has flushed through and is growing actively. Atlantis is most effective on small weeds with two to three leaves and, with most blackgrass at this stage now, growers need to get out there and tackle it.”

Applications of Atlantis should be partnered with an appropriate residual partner for the best results, he added.

For oilseed rape, however, Mr Freer strongly advised growers to delay applications of Kerb (propyzamide) until soil temperatures drop.

“Kerb is far more effective when the soil cools to around 8C,” he said. “The half-life at this temperature is double that at 15C.

“Today soils are around 13 to 14C and it will be about three weeks before the soil temperature is low enough for growers to benefit from the full 120 days half-life.”

Kerb needs time to penetrate the soil profile to reach the grass weed root zones and it starts to degrade upon contact with the soil surface.

To make the most of the herbicide, Mr Freer said growers needed to ensure that sufficient active ingredient reaches the root zone.

“I strongly advise growers to wait,” he said. “The frost this weekend shows that the weather is turning but the soil acts as a buffer and takes time to cool.”

Dow AgroSciences’ technical expert Stuart Jackson said conditions were now right for winter wheat growers to use Broadway Sunrise.

“With grass weeds at the two to three-leaf stage, and soil temperatures above 8C, it’s the ideal time to apply Broadway Sunrise on winter wheat as well as on rye and triticale,” he added.