Spotted Knapweed Control

By: David Runk/AP
By: David Runk/AP

An effort to fight an invasive plant with insects that eat it has drawn opposition from beekeepers who worry it will leave them without an adequate source of nectar and pollen for their honeybees.
Researchers in Michigan released bugs that feed on spotted knapweed earlier this year. Western states and big honey producers, such as Minnesota and Wisconsin, previously used so-called biological control to help restrain the flowering plant, which produces chemicals that deter the growth of other plants and crowds out native vegetation.
It's not clear why Michigan beekeepers are so worried about knapweed control when those in other states haven't been as much. Some in the industry speculated Michigan beekeepers may rely on knapweed more for nectar and pollen than those in other states. Regardless, Michigan is among the nation's top 10 honey producers and the home of beekeepers who ship hives as far as Florida and California to pollinate orchards and fields. Beekeepers argue that if they're hurt, the farmers who rely on them will suffer too.
"If it wasn't for this plant, we wouldn't even be here," said Kirk Jones, the 57-year-old founder of Sleeping Bear Farms in the northwest Lower Peninsula community of Beulah. If knapweed control efforts prove successful, he said: "It could be detrimental to the future of the beekeeping industry."
The dispute between the state and its beekeepers is happening amid a massive die-off of bees nationwide. Colony collapse disorder has killed about 30 percent of the nation's bees each year since it was recognized in 2006, according to a report the U.S. Department of Agriculture released Friday. The bees are crucial for the production of 130 crops worth more than $15 billion a year, it said.
Michigan officials said they're keenly aware of the importance beekeepers place on knapweed, which blooms in late July and early August when many other plants aren't flowering. As part of the knapweed fight, they're looking at what kinds of native flowers could be planted to replace it -- both to sustain bees and improve the diversity of wildflowers statewide.
"It's not an attempt to take away a resource that beekeepers find valuable, but to replace it with one that might have more functionality," said Ken Rauscher, director of the pesticide and plant pest management division for the Michigan Department of Agriculture, which worked with federal officials to oversee the release of knapweed-eating bugs.
Beekeepers, however, are skeptical about other flowers' ability to do the job.
Spotted knapweed, also known as starthistle, was introduced in the U.S. from Europe in the late 1800s. It was brought over accidentally, either in contaminated seed or ships' ballast water, according to the U.S. Department of Agriculture. The plant has been seen in Michigan for at least a century but has spread more vigorously in the past two decades. It thrives in sandy soils, such as dunes, and in former farm fields, along roads and in prairies.
Many beekeepers have set up shop near large expanses of knapweed, said Roger Hoopingarner, president of the Michigan Beekeepers Association. Its loss, and a subsequent loss of bees, would hurt honey production, but the bigger effect would come from not having bees to pollinate fruit and vegetable crops, he said.
Michigan is second only to California in the diversity of crops it produces and is among is among the nation's leaders in the production of red tart cherries, apples and blueberries -- all of which need pollination.
"If spotted knapweed goes away and there is nothing that will replace it, then some of these beekeepers . . . will just leave the state," Hoopingarner said. "They go now to California or other states for pollination, and they won't come back because there will be no incentive to come back."
Two knapweed-eating flies were released in Michigan in the 1990s, but those don't appear to have curbed its spread, Rauscher said. So in August, researchers released two types of weevils on state land in five counties. Scientists in other states have found success in killing off knapweed with a combination of flies and weevils.
Michigan officials don't expect to wipe out knapweed; the hope is to pare it back. Doug Landis, a Michigan State University professor who specializes in biological control, is working with the state on the project. He said replacing knapweed with other flowers is a must because of the way Michigan beekeepers use the plant.
"That will maintain the nectar flow," Landis said.
Terry Klein, 70, of TM Klein and Sons Honey in St. Charles, has about 1,000 colonies of bees in central Michigan. He said he fears the economically-troubled state won't have the resources needed to fully replant areas where knapweed is killed off. The burden will be on beekeepers, who will have to raise the prices they charge Michigan farmers for pollination, he said.
"To me, it's a double-whammy," Klein said. "Costing Michigan jobs. Costing our status as a fruit-growing state."
The pilot project will be evaluated over the next year or two, and Michigan officials don't expect to release more insects until that is done, Rauscher said. Even if the project is expanded, it could be 10 to 15 years before the bugs have a substantial impact on the presence of knapweed, leaving time for beekeepers to adjust, he said.
And, the Michigan Beekeepers' Hoopingarner added, even if Michigan doesn't introduce more bugs, they could eventually spread there from surrounding states where they're used to control knapweed.


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