Wild parsnip gaining ground

Wild parsnip, an invasive plant not native to the United States, is common in Iowa, frequently seen in ditches alongside roads. The plant will produce blisters on skin and a painful burning sensation if touched.

JANESVILLE -- Lacy, yellow-green heads bobbing in the breeze look like they belong. Though considerably taller, the patch of ridged stalks supporting the tiny flowers sways along with Iowa natives.

Motorists along U.S. 218 in Bremer County might not notice, or if they do, might wonder why the oddly unique plants dominate the ditch in places.

Wild parsnip is not the only non-native, invasive species in the state. But unlike others, it bites when broken and its juices flow.

"It is a dangerous plant for several reasons, and probably human health is at the top of the list," says Mark Renz, an authority on invasive plants at the University of Wisconsin.

When wild parsnip sap contacts skin exposed to sunlight, a rash leading to blisters will develop. The clinical name is called phytophotodermatitis. Lingering effects may include scars and discoloration of the skin that lasts up to two years.

Some sources also list temporary or permanent blindness as a possibility.

Described by botanist David Eagan as "the evil sister of Queen Anne's lace," wild parsnip is well established in Iowa. Authorities say it is now likely expanding its range.

But the species is not well-known, according to Chris Henze, roadside vegetation manager and weed commissioner for Johnson County's Secondary Road Department.

Controlling wild parsnip, an aggressive Eurasian weed up to 4 feet tall, is relatively easy, according to authorities. Jabbing a shovel through the root just below ground level will kill the plant. Herbicides also are effective.

Mowing can play a role, too, but it must be timed appropriately. Care should also be taken not to come in contact with shredded leaves and stems that will inevitably be sprayed by whirling blades. For the same reason, experts advise against using string trimmers for the job.

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