Oxfordshire farm manager Colin Woodward is responsible for 1000ha of combinable crops on the Great Tew Estate. Across the farm, winter wheat yields average 10.2t/ha as part of a rotation of winter barley–oilseed rape–winter wheat– beans or maize. The rotation is adjusted to include some spring barley where there’s been a black-grass issue.
The main cultural control for black-grass is spring cropping – three or four years of continuous spring barley is used when black-grass has become very problematic. Rotational ploughing in an otherwise min-till system, further aids Mr Woodward’s black-grass control.
As well as black-grass, the weed profile includes some wild oats, brome and cleavers. “The vast majority of the land doesn’t have much black-grass. We’ve just got some small areas where there is a clear explanation for the problem:the land is on contract: there’s been a tenant on the estate or where there is a drainage issue.”
“To control black-grass in the winter wheat we usually apply Avadex (triallate), followed by a flufenacet base with diflufenican and pendimethalin pre-emergence. Depending on the black-grass pressure, we’ll apply more flufenacet or flufenacet plus Atlantis (mesosulfuron+iodosulfuron) post-emergence in the autumn.”
“Last year we got stuck with some black-grass in a field of winter wheat. We couldn’t travel on the heavy clay to get the autumnal post-em on, so we tried Monolith (mesosulfuron and propoxycarbazone) in the spring. It contains propoxycarbazone and we wanted to try something different."
“The black-grass was fairly well-tillered by the time we got on, yet the Monolith achieved about 40-50% control. The black-grass has been tested and is RRR resistant now, so we need to control it early really.”
Mr Woodward sees Monolith as the best option to apply when land didn’t receive a scheduled autumn post-em – although ideally, he still prefers Atlantis in autumn to hit black-grass when it is very small.
“This year we’ve got on with all the pre-ems and autumn post-ems. Control so far is looking good but It’s good to know that Monolith (mesosulfuron+propoxycarbazone) is there if we need it for crops that didn’t get an autumn post-em.”
A highly active herbicide (including a sulfonylurea herbicide) with foliar and some root activity against black-grass.
Depending when you drilled your wheat crops, weed control in spring 2019 might be looking like either a huge challenge or a case of finishing off the good work