Eric Johnson on weed science challenges of yesterday, today, and tomorrow


As weeds evolve, weed science must evolve to keep up. Today’s weed scientists work hard to tackle evolving herbicide resistant weeds and offer solutions to keep farmers one step ahead.

Eric Johnson, weed scientist with the Agronomic Crop Imaging lab at the University of Saskatchewan, has been working on these solutions for decades through his work in Saskatchewan and through the Canadian Weed Science Society (CWSS). The group met last week at Halifax, N.S.

In the late 1990s, CWSS evolved from the Expert Committee on Weeds (ECW) to fill the need for a professional organization where both public and private professionals could work together on issues in weed science, he says. Collaboration and cooperation has grown overtime in the challenge to keep weed science cutting edge — the group also works with the Weed Science Society of America and the Canadian Society of Agronomy to increase the knowledge base driving change.

Johnson says throughout his career he has seen the focus of weed science evolve. In the 1980s and 1990s ,weed control revolved around herbicide development and evaluation, as there was many new herbicides on the market each year. In the late 1990s fewer herbicides were being developed and the focus of weed science shifted to investigating non-chemical techniques to integrate into conventional crop production. Johnson says weed ecology — the understanding weed life cycles, is giving researchers more insight into weed management in the face of herbicide resistance.

The biggest issue facing weed scientists right now is herbicide resistance, and not just here at home, but around the world.  While there may be a few new modes of action identified every few years, there’s not guarantee they all make it to market. Complicating the issue is an increase in species, including kochia and wild oat, showing multi-mode of action resistance.

Chemical advancements aside, weed scientists are looking into alternative forms of weed control, too. Cultural practices, such as increased seeding rates, and mechanical techniques, like rotary hoeing and inter-row cultivation are in the mix. Johnson says there’s also work being done on harvest weed seed management with seed destructors that are placed on rear of the combine to pulverize weed seed to prevent viable seed from remaining on cropland.

Johnson says there is the possibility of a new wave of herbicides especially in more minor crops but he is not optimistic. He explains moving forward there is emphasis on developing precision herbicide application, using technology to recognize weeds and target them directly. Johnson says with precise application techniques farmers can combine herbicides with different modes of action to fend off herbicide resistance.

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