CombCut put to test in organic trial

Thistles dominate a check strip purposely left in an organic wheat field at the Ian N. Morrison Field Research Farm in Carman. Photo: Shannon VanRaes

Mechanical weed removal without intensive manual labour possible with Swedish implement

By Shannon VanRaes
OrganicBiz staff

Like a spiky purple mohawk, thistles dominate a check strip purposely left in an organic wheat field at the Ian N. Morrison Field Research Farm in Carman.

Pointing to it, the farm’s senior technician Keith Bamford tells a groups of producers and researchers that if not for a piece of equipment known as a CombCut, the entire field would have been worked under by now.

“This was a field that was seeded really early this spring,” he said. “I thought I was going to get a jump on some thistles and that didn’t happen … the thistles came up almost as quickly as the wheat did and it looked like a disaster in the making.”

And so it would have been if not for the Swedish-made device, which developers believe could play a key role in not just organic systems, but also in the fight against herbicide-resistant weeds.

“For those that aren’t familiar with a CombCut, you have the blades and there are no moving parts except the reel, so it’s really using two blades and spacing to cut off wider than desirable weeds,” said Bamford. “This can be used for thistles, it can be used for wild mustard, anything that is thicker than say wheat.”

According to the implement’s developers at JustCommonSense, the implement’s static knives work like tiny scythes, catching and cutting broadleaf weeds and volunteers, while slender crops like wheat slip through unharmed. In crops too thick or bushy for the machinery to comb through, it can be raised above the canopy to shear off weeds that are out pacing a given crop.

They have actually regrown, but the regrowth is really spindly and that is kind of what we were looking for. – Keith Bamford

Several of those participating in the University of Manitoba’s annual Ecological and Organic Farming Field Tour last week had seen video footage of the CombCut in action, but few has seen the results. Bamford stressed that anyone interested in using a new weed suppression technology should incorporate a check strip into their fields to judge efficacy.

Beyond the check strip at the research farm a reduction in thistles could easily been seen, and those that remained lacked the vigour and height of their uncut neighbours.

“They have actually regrown, but the regrowth is really spindly and that is kind of what we were looking for,” said the technician. “It’s set them back and they are now below the wheat canopy, so the wheat now has the advantage … There are still thistles there, it’s not gotten rid of the thistles, but it’s made the crop more competitive.”

He noted there was some damage to the wheat as well, but added using the CombCut earlier in the growing season have reduced that damage. But given the choice between light damage and losing a field to weeds, the answer is clear.

“It’s not going to make our crop better, but it’s going to preserve some of that crop,” Bamford said. “I don’t think we’re going to increase our yields, but we’re not going to lose more, we’re not going to have as many thistles going to seed out here.”

Thistle reduction will also make harvesting the wheat easier, he added.

“And it we’d been able to get into this field of wheat earlier, if we’d done that treatment much earlier, I think the response probable would have been stronger,” he said. It’s just that balancing act between the weeds and the crop.”

Whether the using the CombCut will provide a long-term reduction in weeds, year over year, remains to be seen, but Bamford expects more research will be done on the recently developed implement in the coming years.

“There are lots of ways of dealing with perennial weeds,” he said. “But when all of that falls apart, it’s nice to have a tools like this that we can sort of fall back on, and I’ll say, sort of rescue a crop.”