MOST BLACKGRASS has now emerged and is at the ideal growth stage for effective herbicide control, experts have advised.
Even after extended germination this season and late drilling of many wheat crops, the majority of surviving blackgrass is at the 2-3 leaf stage, according to BASF and Bayer CropScience trials.
“There is no point waiting a minute longer for the later germinators to emerge,” said Bayer‘s Barrie Hunt. “Trials show that you can lose up to a tonne a hectare by delaying Black-grass control until spring.”
Blackgrass in fields drilled in September is generally at the tillering stage, but in many October-sown fields it is at the recommended 2-3 leaf stage for spraying, said Clare Tucker from BASF.
But some later sowings are still seeing protracted blackgrass germination now, added James Clarke from ADAS.
“We don‘t know whether it has all emerged yet. I recommend growers look at it on an individual field basis. It is vital to hit blackgrass hard when it is relatively small.”
To achieve effective resistance management, as well as covering late emerging weeds, he recommended growers use a strong residual component to their control strategy.
A technical factsheet providing useful background information on grassweed resistance can be found on the Weed Resistance Action Group website, he noted.
Both BASF and Bayer recommend using a combination of Atlantis WG (iodosulfuron-methyl-sodium + mesosulfuron-methyl)+ Stomp 400 SC (pendimethalin).
The mainly contact activity of Atlantis and the residual activity of Stomp will help combat the range of growth stages, they said.