justnorth posted on June 15, 2007 07:39 :: 1989 Views
Three noxious and invasive weeds that are common along roadsides and grasslands are just getting ready to flower, making this an excellent time to take steps to control them and limit their ability to spread.
Canada thistle, wild parsnip, spotted knapweed, like many other invasive plants, spread primarily by seed. Mowing down these plants just prior to them flowering may prevent or reduce the spread of seeds, says Kelly Kearns, plant conservationist with the Department of Natural Resources.
“Early June is the time to mow for many of these species,” Kearns says. “As they are just starting to flower at this time they can be easily identified and knocked back. Although mowing can reduce their spread, generally eradicating these invaders takes a number of years and a combination of pulling, cutting, prescribed fire and/or carefully applying herbicide.”
Anyone tackling weed control should be careful of the plants that they are working with, Kearns says, as some have effective defense mechanisms. Some plants, like the purple flowering non-native thistles and multiflora rose, are heavily thorned.
Wild Parsnip
One particularly dangerous plant is wild parsnip (Pastinaca sativa). It can cause serious burns when bare skin comes into contact with the parsnip flowers, leaves or stems in the presence of sunlight. Wild parsnip is a common roadside weed that is rapidly spreading in Wisconsin.
“Now is the best time to recognize wild parsnip because it sends up large, coarse flower spikes and yellow umbrella-like flower clusters generally beginning from the first of June to early July. The long, divided basal leaves can be only a few inches high, but the flowers generally reach 2 to 5 feet,” she says.
“The best way to control wild parsnip, like any invasive plant, is through early detection and eradication. Learn to identify the plant in all of its stages of growth and keep a look-out. As soon as a small population is located, begin control efforts to prevent it from spreading seeds. With many people watching for this plant we can contain its spread and spare others the pain of parsnip burns,” Kearns says.
More information on wild parsnip can be found on the Invasive Species pages of the DNR Web site and in an article on wild parsnip published in Wisconsin Natural Resources magazine.
FOR MORE INFORMATION CONTACT: Kelly Kearns – (608) 267-5066
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