Get Out of the Weeds – Use the Right Tool for the Job

Apr 08, 2022

As our minds turn to gardening and hopes of warmer weather, we might think about weed control. There are many choices of herbicides at the store – but which one is right for your weed problem? The April 7^th 2022 Sustainable, Secure Food Blog explains that while there is no one-size fits all solution, there are ways to chose the right solution for the right problem.

According to blogger Timothy Durham, hand pulling weeds can be a prudent solution. This is especially true if your weeds are few and far between. “But herbicides can be a gamechanger, if you ‘use the right tool for the job.’ Herbicides are designed to chemically manage weeds: devious, out of place plants that sabotage our fragile green thumbs.”

Unfortunately, there is no “Swiss Army Knife” of herbicides. They’re as diverse as a mechanic’s toolkit. Avoid the temptation to pluck anything from the shelf and apply it indiscriminately. Selection must be intentional – a careful alignment of herbicide properties with the weed(s) in question.

Fortunately, herbicides are grouped in straightforward ways, often in very black and white pairings. It’s important to understand how these branch points guide the decision-making process, so an appropriate choice can be made.

Pre-emergent herbicides are a pre-emptive strike. When applied and watered into the soil, they create an inhibitory chemical barrier around ungerminated weed seeds, preventing sprouting. Established plants are spared because most of their roots lie outside this shallow barricade.

Obviously, pre-emergent herbicides must be applied in anticipation of a problem. It’s also a solid option for newly prepared beds. If weeds are already growing, you’ve missed the window of opportunity. As an alternative to pre-emergent herbicides, consider growing cover crops in your garden, yet another valuable tool to keep weeds at bay.

Post-emergent herbicides are reactive, requiring a newly germinated (or established) weed.

Another comparison of herbicides is to look at Selective (Narrow Spectrum) vs. Non-Selective (Broad Spectrum). This pairing is a subset of the above. Does the situation call for a delicate surgeon’s scalpel (that only targets certain weeds), or a blunt force clubbing (an indiscriminate herbicide)? If you’re looking to perform a “reboot” in the garden and start from scratch, broad-spectrum herbicides are your best bet. Otherwise, you’re probably in the market for some selectivity based on the weeds present.

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Video: From Students to Solutions | On The Brink: Season 2, Episode 14

Ask Canada’s most decorated soybean breeder his favourite part of the job and he doesn’t name a single variety. He names the students.

Istvan Rajcan is a professor of soybean breeding and genetics in the Department of Plant Agriculture at the University of Guelph, where he has run the soybean breeding program for 28 and a half years. In that time he has developed 87 soybean cultivars, published 140 refereed papers and trained 51 graduate students. In 2025 he received the Public Sector Impact Award from the National Association for Plant Breeding.

He is also worried. In this episode he says Canada is at a crossroads, pointing to recent government cuts to plant breeding programs and to the facilities that support them. His prescription is structural. "Plant breeding funding formula has to be a long-term one," he says.

The formula he is defending is the public-private matching arrangement his program runs on. Private seed companies fund the work, provincial or federal money matches it, and the combined pool stretches each dollar further than either source could alone. At the National Association for Plant Breeding annual meeting in June, he says American public breeders were often surprised at how well that collaboration works in Canada.

He also describes how the people entering plant breeding have changed. His early graduate students came mostly from farms. More recently they include, in his words, "city kids who just became excited about genetics."

Topics covered:

Why public-private plant breeding funding in Canada needs a long-term

commitment rather than a larger one

How matching private seed company investment with provincial and federal

dollars multiplies research capacity

How the graduate student pipeline into plant breeding has shifted from

farm kids to city kids