Ontario Grain Farmer April/May 2024

23 ONTARIO GRAIN FARMER APRIL/MAY 2024 Sikkema has witnessed the evolution of the weeds that plague Ontario grain crops and has been instrumental in helping farmers manage weeds and increase yields along with their bottom lines. weed control. Vink discovered that applying $5 worth of 2,4-D before planting soybeans increased weed control to 95 per cent. “Within a year or two of Joe completing his M.Sc. research, almost the entire industry switched based on his work on controlling glyphosate-resistant ragweed,” he says, adding that there are many more graduate students whose research results have similarly benefited farmers. LOOKING FORWARD “Weed management in the future will be far more reliant on diversified, sustainable programs,” he says. He foresees more farmers using combinations of cultural (e.g. rotating crops, narrowing row widths, planting cover crops), biological, mechanical, and chemical weed control techniques. On the mechanical side, there is a harvest weed seed control where grinders pummel the weed seeds, so they’re no longer viable before leaving the combine. There are also flamers, robots, and lasers. He sees a number of new techniques emerging to manage weeds on farms, including more ‘see and spray’ precision application technology, which has the added advantage of reducing the environmental loading of herbicides.“I think herbicides will continue to be one component of a diversified weed management program,” he says. Sikkema says that the approach to weed management needs to be re-evaluated, particularly in light of weeds like waterhemp, which has evolved resistance to five herbicide modes of action in Ontario. In the ten years since its presence was first documented in Ontario, glyphosate-resistant waterhemp has been found across southern Ontario. “If a farmer finds waterhemp in the field, the strategy needs to be near-perfect weed control and zero weed seed return to the soil,” he says, contrasting this with strategies from 30 years ago when getting perfection would be seen as spending too much money on weed management. In those days, economic cost-benefit analyses could lead farmers to choose not to control certain weed species when they were present at low densities. He is convinced that weeds will continue to evolve resistance to more herbicide modes of action over time. That’s why he recommends farmers work on diversified weed management programs that use multiple herbicide modes of action over several seasons in a corn, soybean, and wheat rotation and incorporate mechanical, biological, and cultural techniques. In terms of the effects of climate change on weed management, Sikkema cites a United States Department of Agriculture study which showed that current herbicides are degraded more rapidly in the soil because of increased soil temperatures and heavy rain events, shortening the amount of time that herbicides provide residual weed control. “I think that you could have shifts in weed species composition over decades rather than years in response to climate change,” he says. “Things continue to change all the time – just look at the current problems with multiple herbicide-resistant waterhemp.” Sikkema says that while he will be slowing down in his retirement, he will continue to ‘dabble’ in weed research and would like to continue providing the latest information on weed management to Ontario farmers. • SHIELD YIELD YOUR Shieldex® is a registered trademark of Ishihara Sangyo Kaisha, Ltd. Always read and follow label directions. Learn More At gowancanada.com STRONGER ON THE TOUGHEST WEEDS FLEXIBLE ON YOUR CROP ROTATION NEEDS BUY 4 - GET THE 5TH FREE! JANUARY 15TH - JUNE 30TH, 2024 FOR EVERY 4 JUGS OF SHIELDEX 400 SC PURCHASED BETWEEN JAN 15TH AND JUNE 30TH, 2024, GROWERS ARE ELIGIBLE TO IMMEDIATELY GET A 5TH JUG FREE OF CHARGE AT POINT OF SALE AT YOUR PREFERRED RETAIL.