Growers must make their first attack on difficult black-grass with a well-timed pre-emergence spray – don't use the pressures of a busy work period as an excuse for a delay, says Richard Allen of Cambridgeshire-based Allen Agriculture Ltd.
A pre-emergence herbicide not only controls the first flush of weeds, minimising competition with the crop as it establishes, but also leaves growers with more options later on when other jobs and weather conditions can make getting onto the fields difficult.
"A heavy workload and additional input cost when resources are stretched can discourage growers from a pre-emergence herbicide application," says Mr Allen. "But a planned sequence of herbicides is essential, and if you don't accept a cost at this end of the season it can cost dearly in yield at harvest.
"It's worth hiring a contractor if need be to ensure sprays get on in time. We've seen improved weed control on farms using our spray contracting service where, otherwise, the pre-emergence timing would have been missed.
"Flufenacet-based pre-emergence herbicides give the best results and, where labour is short, Liberator's (flufenacet + diflufenican) low 0.6l/ha dose rate can help speed up turnaround of sprayers and manpower, particularly on bigger farms," he suggests. "Triple-rinsing is also quicker as Liberator washes out easily without leaving stains."
Yorkshire grower Keith Wells found Liberator performed well when he used it for the first time on some very wet, heavy clay land last year. "Spraying grass weeds at this early stage is ideal, as you often can't even walk on the land later in the autumn.
"I might try Liberator on some other land this season. If there's a lot of rain sprays can easily be delayed and the post-emergence products don't tend to work so well in spring."
Mr Allen adds an additional point on timing: "If cultivations are carried out a week or so before drilling, growers should account for the fact that black-grass can start to chit and grow from then onwards, not just following the drilling date. So I'd say growers should aim to spray within three days of drilling."