Biological explosions of invasive weeds that have occurred throughout the United States are now being found in Graham and Greenlee counties.

Kim McReynolds of the Willcox University of Arizona Cooperative Extension Pro-gram warned members of the Gila Watershed Partnership that ecologically devastating invasive weeds are finding their way to southeastern Arizona.

McReynolds said an invasive weed species is "an alien species whose introduction will cause economic harm or threaten public health." This differs from the standard definition of weeds, which is a species whose negatives outweigh the positives, she said. Members of the public tend to confuse this with noxious weeds, which are undesirable plants regulated by law.

Ten years ago, concerns about invasive weeds were minimal, she said. After states such as California, Montana and Wyoming have suffered millions of dollars in damages, concern and awareness has been heightened.

"Right now, Arizona isn't overrun," McReynolds said, "but Montana is."

Montana is plagued by Spotted Knapweed, which causes $42 million a year in forage losses. Experts estimate the state will lose about $150 million a year in forage by 2009.

Water runoff increased by as much as 56 percent in areas dominated by the plants, McReynolds said. This plant is also found in Gila and Apache counties.

California is another state suffering from a biological explosion of invasive weeds. It is also found in Gila, Navajo and Apache counties.

The Yellow Starthistle was introduced to the state in the mid-1800s, McReynolds said. In 1958, one million acres was populated by the plant. By 1985, 8 million acres was populated with the plant. Today, 15 to 22 million acres of the state is covered by the plant, she said.

McReynolds said horses eating the plant suffer from chewing disease caused by the plant's large thorns.

This causes the horses pain while chewing and eventually leads to their starvation, she said.

Besides interfering with grazing, Yellow Starthistle also depletes soil moisture.

While these two plant species are hard to find in Graham and Greenlee, their sister species are not.

Malta Starthistle can be seen growing near Stockton Wash and Highway 191, McReynolds said. While driving to the meeting, she said she saw the thorny plant had multiplied.

Malta Starthistle grows from one to two feet in height and features yellow flowerheads with purple-or brown-tipped spines.

McReynolds said Greenlee County has three types of thistle, which is startling when compared with zero kinds of thistle in 2002. Scotch, Musk and Bull thistle have grown over the last two years, she said.

"They've got wicked thorns," she said. Russian Knapweed has also been found near Duncan.

McReynolds credited Dave Fisher of the National Resources Conservation Service with discovering the Sahara Mustard plant near the old Pima gym.

Sweet Resin Bush is known to inhabit Frye Mesa and was recently the focus of a herbicidal treatment. This plant is known to kill its surrounding plants and causes soil runoff.

An invasive species known as Camelthorn was also found by Department of Transpor-tation workers outside of Pima, she said while showing the audience a slide of the plant.

The picture showed the plant growing through the asphalt of a freshly-paved road.

McReynolds noted the plant in the picture had grown through six inches of asphalt. Its spines are so strong that they can actually punch holes in vehicles' tires, she said.

What we can do

McReynolds said the Extension has been focusing on educating road workers by holding workshops to identify the plant.

She also trains county workers and gives them handbooks to help them identify these pests.

This is only part of the strategy to control them. McReynolds is also trying to teach prevention techniques, take inventory of reported plant sightings, plan and coordinate control efforts, start chemical control efforts and monitor the areas populated by these species.

"Besides resin bush, there is no management area that covers Graham, Greenlee and Cochise counties," she said. One of the ways the plants spread from county to county is when seeds stick to people's clothing, vehicle tires and shoes.

By publicizing the looks of these weeds as much as possible, she hopes to prevent the spread of them.

To find out more about these species, look at www.invasivespecies.gov.

To contact John Kamin, call 428-2560 (ext. 240) or e-mail him at johnk@eacourier.com.