Milkweed and Monarchs: Patching it Up Between Farmers and Environmentalists

A springtime initiative launched earlier this week by the David Suzuki Foundation, fashioned after the iconic Got Milk? campaign of yore, asks “Got Milkweed, Canada?” It’s an initiative designed to get urban people to plant milkweed and provide a much-needed food source for North America’s precarious population of eastern monarch butterflies, which require milkweed for their survival.

This year’s pro-milkweed campaign got underway amidst an unwelcomed snowfall and cold weather, which might have dulled its lustre. But given the star power and public relations machine behind it, it’s destined to resonate through the spring with urbanites…provided, that is, they and their neighbours don’t get overrun with milkweed and start considering it a pest.

“Once you plant milkweed,” says Dale Cowan, senior agronomist with AGRIS and Wanstead Farmers’ Co-op, “you will have milkweed.”

That’s the way farmers have seen milkweed, historically. Many have unhappy memories of slogging up and down blistering hot fields in the summer, hoeing stubborn milkweed plants by hand. In the fall, they’d curse the ones they missed, the ones standing six inches taller than the highest soybeans, the ones that feasted all growing season on the commercial crops’ precious water and nutrients.

Milkweed. Photo by Pete Smith.
Photo by Pete Smith.

Advances in technology helped with milkweed control on the farm. In the mid 1990s, glyphosate (commercially sold as RoundUp) was introduced. It was highly effective against milkweed, and other weeds. It was also part of the herbicide-tolerant field crop phenomenon.

“When glyphosate-tolerant corn and soybeans hit the marketplace, it allowed farmers to use an effective herbicide at controlling milkweed,” says OMAFRA’s Mike Cowbrough. “It could be applied safely to the crop, usually at a more advanced crop stage, at a time when milkweed was emerged.” More recently, glyphosate-tolerant sugar beets have hit the Ontario market, which Cowbrough says once again gives farmers an effective herbicide for killing milkweed top-growth and other weeds.

However, an unfortunate and unintended consequence of getting rid of milkweed was that an important nesting and food source for monarchs, which are important pollinators, was reduced significantly.

But times have changed. Milkweed is no longer reviled. Research has shown its value to the ecosystem, particularly for monarch reproduction. And as far as farmers and rural landowners go, milkweed is no longer a weed that must be controlled by law. Last January, the province declassified it as a noxious weed.

So, we’ve gone from killing milkweed, to tolerating it, and now even nurturing it and planting it in the garden, as the Suzuki campaign advocates.

However, huge questions remain about the butterflies themselves.

Milkweed. Photo by Mike Cowbrough.
Photo by Mike Cowbrough.

Research by University of Guelph postdoctoral fellow Tyler Flockhart and Prof. Ryan Norris, and colleagues from Australia, claims monarchs could be headed for near extinction without intervention. The biggest problem is the disappearance of breeding grounds – that is, milkweed plots — primarily in the Midwest US. That was a groundbreaking finding, and it ran counter to the long-held belief that monarch butterflies were most vulnerable to disturbances in their wintering grounds in Mexico, or because of climate change.

“Reducing the negative effects of host plant loss on the breeding grounds is the top conservation priority to slow or halt future population declines of monarch butterflies in North America,” they say in a paper published in the Journal of Animal Ecology last year.

Now, here’s a new development. Research by Norris and his team, sponsored by the Natural Sciences and Engineering Research Council and Syngenta, is pointing to even more value in finding harmony among farmers – those who have to live with milkweeds — and environmentalists bent on saving the monarch.

Early results from research studies conducted this past summer near Long Point, show female monarchs prefer laying eggs on milkweed that grows in small patches or strips of land between farmers’ fields.

The females like those patches better than other places where milkweed typically grows, such as roadsides and naturalized areas.

Norris doesn’t know exactly why the females prefer these particular areas; the research is still in its beginning stages. But he has a few ideas.

For one, he thinks it may be because these milkweed patches are on the small side they typically have fewer males, which are considered a distraction by females when they’re laying eggs and rearing their young.

Photo by Vicki DeLoach, CC 2.0.
Photo by Vicki DeLoach, CC 2.0.

Another hypothesis is that the farmers’ efforts to control insects that feed on their field crops may, in general, reduce the number of predatory insects in the vicinity of the small milkweed patches. The absence of these insects, which would normally be regarded as threats by the females, might create a welcoming environment.

And finally, agricultural practices such as fertilizing and weeding in adjacent fields may be contributing to a favourable growing environment not only for farmers’ crops, but for small milkweed patches, too.

These are preliminary findings and there are still more questions to be answered. But to me, it’s a very encouraging research. It’s well known that friction exists between environmentalists and modern farmers who use technology as production and management tools.

But if these disparate groups could find some common, middle ground – like small, innocuous patches of milkweed on a farm – at least they have a starting point for dialogue. Monarchs and milkweed could be the glue that helps bring them closer together.

Farmers can’t manage fields that are full of milkweed (or any weed for that matter). But with planning, they could handle small, scattered patches of milkweed. Ontario has many fields where such patches could be nurtured and encouraged. True, it’s not an ideal situation for farmers – milkweed seeds are light and easily blow around with the wind. Some will end up in adjacent fields. It could be a particular problem for organic farmers, who don’t use glyphosate.

But overall, this kind of a win-win-win for wildlife, farmers and environmentalists is rare. Given how small milkweed-patch set-asides could help preserve an important pollinating species that tugs at people’s hearts — as well as the need for agriculture to develop a social licence with urban Canadians – it’s certainly worth a longer look.

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