Pre-emergence grassweed control is worthwhile

Hitting grassweeds as early as possible with pre-emergence herbicides will be crucial this season, especially in bad blackgrass situations, experts have told growers.

Many may be tempted to miss out pre-ems given the already busy workloads and additional input cost, but doing so could cost dearly in yield next harvest, warned Cambridgeshire-based, Richard Allen of Allen Agriculture.

“It’s worth hiring a contractor if need be to ensure sprays get on in time.

“Flufenacet-based pre-emergence herbicides give the best results and, where labour is short, Liberator’s (flufenacet + diflufenican) low 0.6 litres/ha dose rate can help speed up turnaround of sprayers and manpower, particularly on bigger farms,” he said.

Frontier’s Bob Mills also saw good results from flufenacet-based pre-em herbicides followed up by Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium) in the autumn or spring, in trials last year.

“The best treatments were from the flufenacet-based herbicides, with Ice [flufenacet + pendimethalin] applied pre-em followed by Atlantis and Treflan [trifluralin] applied pre-Christmas showing a 2.5t/ha benefit over less effective pre-ems like straight trifluralin and prosulfocarb.”

It is also worth considering stale seedbeds, he continued, as hot weather during June and July means dormancy levels in blackgrass are relatively low – which should mean early weed germination.

“100% control is unlikely in any situation, but getting as close as possible has to be the aim. It will be very appropriate to use a stale seedbed and it might be reasonable to expect 50% control from one this year.”

For more on blackgrass control, see p.58 & 59 of this week’s Farmers Weekly magazine (1 September).