Invasive plants highlighted during Weed Awareness Week, May 20-27
They are often called a biological wildfire. Invasive noxious weeds are plants that have been introduced into an environment outside their native range. In this case, they have come to Oregon, and cause environmental and economic harm to some degree in all regions of the state. Governor Kulongoski has declared May 20-27 as Weed Awareness Week in Oregon with hopes that the public can help fight the battle against these unwanted invaders.
"We need to be diligent in the war against weeds and go after them aggressively," says Tim Butler, supervisor of the Oregon Department of Agriculture's Noxious Weed Control Program . "Part of the process is educating people about the problems invasive weeds cause and what role they can play. The public can help us look for these weeds and avoid unwillingly spreading them to uninfested areas."
Invasive weeds reduce biodiversity and displace native plant and wildlife species. They invade agricultural land, forests, and other natural areas causing severe production losses, increased control costs, and negative impacts to watersheds and ecosystems. A conservative assessment puts the impact of noxious weeds at $83 million in annual losses. Nationally, that figure is estimated at $24 billion.
"All the regions of Oregon- from the coast to the Idaho border and all points in between- have invasive noxious weed issues they are trying to deal with," says Butler.
As part of Weed Awareness Week, ODA is highlighting a noxious weed in each of six geographic regions of the state. Some of these weeds are in the process of being eradicated, others are too well established and can only be contained or intensively controlled. With 105 state listed noxious weeds, these species are just a few representatives keeping ODA and various land managers busy this year.
Oregon Coast: Gorse, a very invasive weed, is drawing a great deal of attention. Although there are small infestations on the north and central coast, Coos and Curry counties are heavily populated with gorse. An extreme fire hazard due to the oils it produces, gorse out-competes young seedlings in forests and excludes wildlife. Active control programs are underway to keep gorse contained and from spreading inland. ODA has had limited success in using biological control by releasing a seed weevil and a spider mite, both natural enemies of gorse. Other biocontrol agents are being looked at for the future.
Willamette Valley: Giant hogweed is both a state and federally-listed noxious weed, which means it is a very serious invader. Found predominately in the Portland metro area, it has been planted as an ornamental by unsuspecting gardeners because it is a showy plant. But giant hogweed can be very invasive, especially in riparian areas. There are also human health consequences attributed to hogweed. Its sap can produce severe burns and blisters on a person's skin. ODA and its partners are trying to eradicate giant hogweed and have made good progress. The number of sites where it has been found has decreased the past couple of years. Herbicides and digging are the two methods of control.
Southwest Oregon: Yellow starthistle covers many acres in Jackson, Josephine, and Douglas counties. It is also found in parts of Northeast Oregon and occupies 1.8 million acres statewide. The spiny-headed plant displaces desirable vegetation. Oregon State University, working with climate and soil data, estimates yellow starthistle could explode from occupying just five percent of Oregon's land to 50 percent if not held in check. A team of seven biocontrol agents has been used against yellow starthistle, and the combination is showing some positive results. Eradication is out of the question, but ODA is hoping to at least keep it from spreading.
Central Oregon: Spotted knapweed is a very aggressive noxious weed that easily moves along highway corridors, especially in the Bend-Sisters area. Oregon is hoping to avoid the problem in Montana, where more than five million acres of rangeland is covered with spotted knapweed. Currently occupying about 1.4 percent, OSU projects this weed could spread to about 90 percent of the state if not kept in check. Working with the Oregon Department of Transportation (ODOT) and the U.S. Forest Service (USFS), ODA has been using herbicide treatments and a dozen species of biocontrol agents to help fight this invader.
Northeast Oregon: Common bugloss is a recent addition to the noxious weed list. It invades pastures, pine forests, and rangeland. The fleshy stalks can cause hay bales to mold. Working with USFS and county weed control programs, ODA has targeted this weed for another reason- it is threatening a desirable but endangered plant species in the area (Mac Farlane's 4-o'clock). Common bugloss is being controlled by herbicides.
Southeast Oregon: Perennial pepperweed, also know as tall white top, is extremely competitive and degrades nesting habitat for wild birds. The weed can grow up to six feet tall and is especially troublesome in the Malheur Wildlife Refuge. Active projects involving landowners, including the national refuge, are underway to control the noxious weed. It is also a problem in Harney and Lake counties. Herbicides are used for control.
ODA has staff in each of these regions to help coordinate activities with land managers and county weed control programs, where they exist. The staff also works to implement on-the-ground control projects. It's a daunting task but important in the protection of Oregon's natural resources. The public is encouraged to help.
"We need to keep these things from being moved- either into the state initially or from spreading them within the state from point A to point B," says Butler. "Be aware not to spread the weeds when you are camping, hunting, and fishing. Clean your equipment, boots, and vehicles. Off road vehicles like motorcycles, ATVs, and four-wheel drive trucks provide easy ways to carry weeds from one area to another."
There have been successes in the fight against invasive noxious weeds in Oregon. But there will never be an end to the war. The upcoming special week may bring some attention to the cause, but it may take 52 weeks a year to truly make a difference.
Pictures and profiles of the above noxious weeds can be found on the Noxious Weed Control Program page.