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Weed Wisdom Jan. 2019

News article


How does hockey relate to weed management?

by Jonathan Rosset

First, I would like to thank Dr. Geddes for inviting me to take over his column this month and talk about my research. Over the past 2.5 years at the University of Manitoba, I have been examining how cultural weed management practices help reduce the time soybean need to be kept weed-free in order to minimize yield loss. Currently, herbicides have the greatest impact on weeds, however other management strategies also play critical roles. To help visualize this, I propose a metaphor where the types of weed management strategies are viewed as members of a hockey team.

In hockey, a team’s success is usually attributed to the strongest player(s) because of their large contributions. However, it’s important to remember that a team only functions as well as its weakest member. In this metaphor, herbicides are thought of as the team’s goalkeeper, the strongest weed management strategy available to prevent yield loss. However, goalkeepers can’t do it on their own and need help from both tough and skillful players alike. Tough players, like mechanical weed management strategies, relieve the pressure on the goalkeeper, yet can be clumsy and imprecise, especially in-crop. As such, cultural weed management strategies are the skillful players capable of influencing the game’s outcome by either easing or adding to their teammates workload. This metaphor refers to the use of an integrated weed management system, with cultural strategies (i.e. row spacing, crop stand density, and variety choice) as one of the essential pillars to effective weed management.


Narrow (left) and wide (right) row soybean kept weed-free until the first trifoliate development stage demonstrate the difference in weed biomass accumulation over the remainder of the season.

In 1968, Jorge Nieto and his team of researchers developed a theory where crops have a critical period during their development where weeds need to be controlled in order to mitigate yield loss. This ‘Critical Period of Weed Control’ begins with the optimal time to remove weeds and ends with how long the crop should be kept weed-free. My research examined how row spacing (narrow vs wide), stand density (low vs med vs high), and variety (DeKalb 2260 vs 2360 vs 2410) affected the end of this critical period in soybean. Results suggest that using narrow row spacing, medium to high stand density, and a competitive variety (well adapted to your growing region) can individually shorten the weed-free duration by up to 2 soybean development stages. While I did not test how all three behaved together, it is likely that this would shorten the period even further. These effective cultural weed management strategies help reduce in-crop herbicide applications by making soybean more competitive against weeds, and also more tolerant to competition from weeds. While soybean is currently grown over a limited area in southern Alberta, these lessons can be applied to any crop.

This research shows the importance of prioritizing the use of cultural weed management strategies when planning for the future. Effective use of these cultural weed management tools will help reduce reliance on in-crop herbicides and extend their effectiveness for years to come, while reducing the selection pressure for herbicide resistant weeds and herbicides’ environmental load. It is difficult to fathom how far we’ve come in such a short time since the ‘Green Revolution’ of the 1960s. Yet, with all our technological achievements, we must still be vigilant that our successes (increased production and mechanization) do not become our shortfalls (herbicide resistance and environmental degradation). Cultural weed management strategies are the skillful players that help us achieve the goal of sustainable weed management.


Created January 15, 2019 | Category: Weed Wisdom

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