Residual stacking takes on a higher priority
Late harvest and recent heavy rainfall combined with high levels of blackgrass dormancy have reduced the effectiveness of stale seedbeds this autumn.“Many farmers have been disappointed,” says Nick Myers, agronomy manager for ProCam. “Soils were either too dry or too wet and with weed dormancy the highest on record, very little blackgrass actually emerged to be treated with glyphosate.
“In effect, this has lessened weed control options this season and brings more focus on getting the best performance we can from residual herbicides. Better soil moisture should help, but the extended germination of blackgrass this year will be a problem.”
One positive aspect of delaying wheat drilling is late establishment can lead to a 30% reduction in black-grass populations. It is also clear that conditions for herbicide application this year are in complete contrast to last season.
“The selection and use of residual herbicides will be essential to ensure good grass weed control this year. Confidence in herbicide performance may have been shaken last year when control was generally well below expected levels, especially compared to the previous autumn.
“This was largely due to dry soil conditions, with soil moisture deficits lasting throughout the autumn. Soil and air temperatures were also well above the long term average. None of these conditions was conducive to effective performance herbicides.”
The major challenge this year has been preparing a fine, firm seedbed which is needed for optimum herbicide performance. Ideal timing for pre-emergence herbicide application, providing soil and weather conditions are suitable, is within 48 hours of drilling.
Mr Myers said growers should consider tank-mixing and/or sequencing pre-emergence residual products such as flufenacet + pendimethalin, flufenacet + DFF, prosulfocarb and pendimethalin to enhance the initial level of weed control.