pest management Horsetail a stubborn opponent

Weed scientist suspects use of chemicals is not efficient and that alternative control measures are needed. By Judie Steeves


y their very nature, weeds are survivors and they’re very good at adapting to new

environments. It’s part of why Jichul Bae finds them so interesting. He is a weed scientist at the Agassiz Research and Development Centre and after nearly a year talking to local berry growers he’s heard many times about the field horsetail problem growers are trying to deal with.

Unfortunately, trying to control it is a real headache. “It’s one of the hardest perennial weeds to control. I suspect it could be resistant to some of the herbicides we use against it,” he adds. That is one of the hypotheses he believes needs to be tested here, where no work has yet been done. “It could be we’re just wasting chemicals, which would also be a waste of money. We need to move to alternative practices.

“We have an over-reliance on herbicides. If they’re used year in and year out, weeds tend to develop resistance to them. Some growers then just increase the dose of chemical, or re-spray.” Bae notes.

Weed scientist Jichul Bae, left, and Ryan Critchley, research

technician, who works with him at the Agassiz Research and Development Centre.


“We need to stop wasting chemicals.”

Instead, Bae believes cultural and mechanical methods of controlling weeds need to be developed. Unfortunately, field horsetail has a rhizome that reaches up to three metres deep in the soil and it can infest an area of one hectare of land within six years of introduction, notes Bae.

Rhizomes spread underground from each fragment of plant left behind, so tilling helps to spread it, rather than kill it.

Although horsetail doesn’t set a seed it does release spores, but mainly spreads under the ground. “Humans have

always battled weeds, and we still do. Weeds are

particularly good at adapting to new environments,” Bae explains.

Field horsetail or common horsetail (Equisetum arvense). 10 British Columbia Berry Grower • Summer 2018

He is especially interested in using living mulches to help suppress weeds. Living mulches are cover crops interplanted or

undersown with a main crop. Such crops can be suppressed by herbicides, mowing or tillage in order to prevent competition for limited resources with a cash crop.

He is a strong proponent of the roller- crimper to lay down and kill cover crops before planting, creating a weed- suppressing, water-conserving mulch. The technique appeals particularly to organic growers.

It’s especially successful against annual weeds and reduces herbicide use and is sustainable, he notes. Bae feels such a piece of equipment would work between blueberry rows. At present, roller-crimpers are used a lot on the prairies.

Bae has worked on combating invasive roadside weeds before joining the ARDC, and on detecting and mitigating the spread and development of herbicide- resistant weeds. He is also looking at development of integrated weed management strategies with agro- ecological intensification approaches. He specializes in integrated weed management, plant community ecology, ecotoxicology and the ecology of weeds and invasive plants.

Bae is a member of the Canadian Weed Science Society, the Weed Science Society of America and the International Weed Science Society.

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