Cool seedbeds buy time for pre-em

Poor seedbed quality brought about by wet autumn conditions is forcing growers to squeeze every last drop of performance from pre-em herbicides.

But with crop growth now slowed by seedbed temperatures 1-2°C lower than normal, a leading agronomist says growers have a welcome reprieve in the race to apply pre-em treatments.

Patrick Stephenson, AICC agronomist, said: “Sluggish crop establishment this autumn will stretch the window for pre-em herbicides, presenting an extension to the usual 48-hour rush to get vital treatments applied.”

Offering good news for growers battling against torrid conditions, Stephenson emphasised the importance of pre-em treatment and urges growers to invest more time and effort in establishing the best possible seedbed to maximise early control. “Don’t hurry to get crops in the ground,” he said. “Time spent getting good-quality fine, firm seedbeds will pay dividends in terms of herbicide efficacy, and wheat crops drilled later will soon catch up.”

To optimise performance of pre-em treatments in any situation, growers should also consider nozzle set-up, he advised. “Coverage over cloddy soils can be helped by alternating nozzles forward and backward. Hawk or conventional nozzles can be used in this format to maximise the soil surface’s exposure to the active ingredient.

“Without doubt, flufenacet is the key active ingredient to start a black-grass control programme, but growers weighing up Liberator (flufenacet + diflufenican) against Crystal (flufenacet + pendimethalin) should be aware of risks from pendimethalin where drilling depth is inconsistent in poor seedbeds. To maintain complete crop safety when pendimethalin use is planned, seed should be drilled to at least 1.5 inches beneath the surface,” said Stephenson.

“Unless a grower is absolutely confident of achieving consistent drilling depth - and I’m seeing a lot of very cloddy seedbeds - I would consider Liberator the safer option,” he said.

But Stephenson admitted difficult conditions will increase the weed control challenge.

“Growers must plan ahead to get the best from flufenacet. Assess potential partners and, with limitations on season-long rates of some actives, growers must decide how they best fit into a strategy.

“Whatever the approach, don’t underestimate the pre-em ability of flufenacet in challenging grass-weed situations - peri-emergence timing will compromise efficacy.”