Clearfield oilseed rape is reinforcing its potential as a mainstream OSR choice on a Hampshire estate, where it is being grown on a field with a history of charlock infestation that almost wrote off the last crop of OSR in 2013.
“We said we would never grow oilseed rape in that field again,” said Michael Maxwell, farm manager at Preston Farms, Preston Candover near Winchester. “It was so bad our combine driver asked me if I really wanted him to cut it.”
After a discussion with his agronomist, Ben Burrows, however, he opted to take advantage of the Clearfield system to maintain the estate’s five-year rotation on the 27ha field this season; a decision that proved right despite mid-September sowing into decidedly poor, wet seedbeds.
“We subcast the DK Imperial CL into the flinty clay loam ground much later then we’d planned following serious winter barley harvesting problems,” Michael explained. “Our converted Flatlift cultivator did a reasonable job despite the conditions, sowing around
55 seeds/m2 in 50cm bands.
“Helped by the variety’s vigour, an open autumn and far fewer pigeon problems than we were expecting, the crop established well and came out of the winter with scarcely a weed in sight. I have no doubt that if it wasn’t for Clearfield, it would be a complete mess.”
Clearfield crops account for around 11% of the OSR area currently being overseen across southern England by independent agronomist, Ben Burrows and his colleagues at Hampshire-based Crop Management Partners (CMP).
“We find the system very effective in helping growers deal with problem areas on their farms,” he said. “The top reason for us is ease of controlling cruciferous weeds which would otherwise make OSR unviable. Using it we’re able to achieve very reliable control of even quite large weeds.
“The Clearfield system gives us the opportunity to omit pre-emergence herbicides which can slow down emergence too. Every bit as importantly, it also means we can wait and see how the crop establishes before spending large amounts on agrochemicals.”
Mr Burrows also values the broad-spectrum of weed control offered by Clearfield herbicides, and the ability to sequence them with other post-emergence herbicides, depending on problem weeds.
The Clearfield crop at Preston Farms received no pre-emergence herbicide, except headland Springbok (dimethenamid-P + metazachlor), which is used on all of the farm’s 162ha of OSR to boost cranesbill control. It then received propaquizafop + insecticide in early October, followed by Cleravo + Dash in late October, then propyzamide a month later.
“We chose Cleravo to keep on top of poppies, in particular,” Ben Burrows pointed out. “It has made an excellent across-the-board job of our weed control as well as dealing extremely effectively with a large charlock population.
“Michael is very pleased with how this first crop has coped with the challenges it has faced. As a result, we’re planning to grow more Clearfield here next season. With the wider benefits we’re seeing with the system, this isn’t likely to be confined to fields where we have known problems with charlock either.”