Scientists are using a sandblaster to shoot corn grit, and walnut shells at common weeds in potatoes, wine grapes, blueberries and dry beans. (Submitted photo/Agriculture and Agri-Food Canada)

By Alice McFarlane

Sandblasting weeds

Scientist look for natural alternatives to herbicides

Aug 31, 2022 | 4:09 PM

MELFORT, Sask. — Herbicide resistance in weeds is a serious and costly problem for farmers and their crops.

A group of researchers at the University of Nebraska have been studying a unique control concept called “abrasive or projectile weed control” in corn crops.

Using a sandblaster, the university research team shoots natural materials like corn grit, corn gluten meal, and walnut shells directly at weeds. They found this alternative to herbicides was an effective way of killing the weeds or severely damaging them in corn crops while reducing costs and environmental impacts.

The could provide a quick, cost-effective, and simple solution for farmers trying to control weeds in their crops and reduce the environmental impact of herbicide use.

Agriculture and Agri-Food Canada (AAFC) research scientists across Canada have teamed up to form the northern chapter of “weed hunters” as part of the Alternative Pest Management Solutions project to reduce pesticide and herbicide use.

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Dr. Robert Nurse with the Harrow Research and Development Centre is leading the study.

“Farmers are finding fewer herbicide options available to them due to resistance from weeds. Projectile weed control could provide them with a safe alternative to destroying weeds that has a very low environmental impact,” Nurse said.

Developing and registering a new herbicide in Canada can cost hundreds of millions of dollars and take 10 to 15 years. The air-propelled abrasives being tested by AAFC would not require registration by Canada’s Pest Management Regulatory Agency.

Without the registration requirement, new projectile materials could be made available to farmers after only two years of small plot testing. As the materials are all natural, farmers could even produce it themselves at a lower cost.

AAFC scientists have started a new two-year project where they chose four high value crops whose common weeds have fewer herbicide options available for farmers and are becoming increasingly resistant to the available herbicides.

They are targeting the five most common broadleaf weeds, or non-grass weeds, in each crop.

Dr. Nurse is hunting weeds in dry bean fields in Harrow, Ont. while Dr. Andrew McKenzie-Gopsill is tackling potato weeds at the Charlottetown Research and Development Centre on Prince Edward Island. Dr. Marie-Josée Simard, Saint-Jean-sur-Richelieu Research and Development Centre in Quebec, and Dr. Jichul Bae, Agassiz Research and Development Centre in British Columbia, are targeting common vineyard and blueberry weeds.

Each scientist is equipped with a commercial sandblaster attached to an air compressor to shoot corn grit, walnut shells, in fine and coarse sizes, and a mix of both materials at a rate of 480 kilograms per hectare, amounting to a couple grams per square metre.

In small plots, some fields will be treated with projectile materials only while others will be treated with projectiles in combination with a reduced rate of herbicide to see if the same weed control can be achieved without any herbicide.

Nurse said it’s all about the right timing.

“We plan to shoot weeds at the same time that farmers might use a herbicide, so it fits into their regular schedule,” Nurse said. “It also lines up to when the weeds are just emerging from the soil and are most susceptible. They can absorb damage from the projectiles better when they get older.”

In two years, the team hopes to find the best projectile material, including its ideal size and application rate, with weed control of more than 80 per cent without causing significant crop injury and yield loss. The researchers also want to see if air-propelled abrasives can reduce overall herbicide application in potatoes, dry beans, vineyards, and blueberries.

University of Nebraska researchers developed a modified crop sprayer to push projectile materials with compressed air through a nozzle over the top of and beside the crop. Dr. Andrew McKenzie-Gopsill said a granular fertilizer spreader would work as well. Both options are simple to modify and would be easy for farmers to implement.

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alice.mcfarlane@pattisonmedia.com

On Twitter: @farmnewsNOW