Warm weather welcomes noxious weeds

With higher temperatures on the way, local Montanans and visitors are hitting the great outdoors in pursuit of warm weather activities, including boating, swimming and hiking.

But the favorableweather and outdooradventures play host to unwelcome guests—noxious weeds.

Montana’s land andwaterways are under siege during the warm season as noxious invaders gain root and spread throughout Big Sky country.

The rise in human activity, trade and commerce over the past 150 years has caused a dramatic increase in the spread of noxious weeds.

 In 1925, noxious weeds were reported in one county in Montana and by 1975, they were present in 21 counties.

Today, noxious weeds are present in all 56 counties covering approximately 7,600,000 acres statewide.

Wind, wildlife, domestic animals, birds, vehicles, boats and people all contribute to this invasion.

During high volume traffic periods, car tires, undercarriages and boat rudders distribute noxious weeds from one place to another.

In addition to choking out native plants, weeds also threaten to reduce economic productivity, as well as the ecological integrity of Montana’s land and waters.

The economic loss from knapweed amounts to $42 million annually, according to a report by Steve Hirsch and Jay Leitch from North Dakota State University’s Department of Agriculture.

Some species of noxious weeds have the potential to affect water quality and the long-term production of land.

They also have the ability to increase surface runoff, as well as affect hydrologic cycles, sediment deposition and erosion.

Some even have the potential to change soil properties, reducing needed water habits essential to native plants and animals.

When exotic weeds are introduced into a native species area, modifications occur to the habitat structure that alters the species interactions within their environment, negatively affecting hunting, ranching, farming, fishing and wildlife viewing.

In an effort to help control noxious invaders and their affect on native plant life, Montana Weed Control Association is promotingawareness through a “Zero Spread” campaign.

Three of the major invaders for this year are Eurasian watermilfoil, purple loosestrife and ox-eye daisy.

A problematic exotic aquatic weed, Eurasian watermilfoil spreads rapidly underwater until it reaches the surface.

Upon breaching water, it forms large plantmats that shade and choke out native vegetation.

This weed is commonly transported by boat rudders and has the ability to reproduce from fragments and spread rapidly in a range of temperatures and conditions.

Milfoil is known, once established, to completely choke out an entire reservoir within two years.

Another wetland invader— purple loosestrife— was introduced to Montana in 1980 and now grows in large stands, suppressing resident plants, killing natural foods and cover, as well as threatening to alter wetland structure and function.

Dense stands also threaten to reduce waterfowl access from water to nesting sites, making these birds more vulnerable to predators. This aquatic invader also has the capability of reproducing from any plant fragment, making it especially difficult to control.

Noxious invaders are taking over pastures, meadows and roadsides as well. The ox-eye daisy, first reported in Lewis and Clark County in 1890, is one such aggressor, as its flower-like features deceive many into thinking of it as a “pretty flower.”

Commonly mistaken for the Shasta daisy, this weed forms dense stands that choke out vegetation used for grazing.

In pastures, the spread of ox-eye daisy has intensified as most plant feeders avoid it and feed on grass instead, allowing for the weed to spread while grasses are depleted.

This weed continues to increase and spread throughout Montana.

There are a few simple steps that can be taken to help prevent the spread ofweeds:

Learn how to identify and eliminate noxious weeds on your property, drive on established roads, clean vehicles and boats before and after recreating, and clean dogs, clothing and gear after spending time in weed-infested areas.

For more information on Zero Spread, and to learn how to prevent and manage invasive weeds, visit www.mtweed.org.