The scene is a desolate stretch of desert somewhere in the American Southwest; the time, dusk. An unsuspecting motorist and his loving wife speed along the highway, unaware of the threat that lurks in the sweep of sand by the roadside.
But wait. The car, plagued by mechanical demons, stops, and driver and passenger alight to check the motor. But the menace doesn't come from under the hood. A pack of killer tumbleweed rolls toward the couple, and a bush leaps to attack the woman's throat. The man pulls his trusty cigarette lighter from his pocket, torches the attacker and saves the day.
The scenerio, an episode from an early television suspense show, isn't far off the mark, for in San Diego County, tumbleweed heads the most wanted list of the county Department of Agriculture, Weights & Measures and is one of the top two problem weeds in the state, according to agriculture specialists. It is insidious, omnipresent, indestructible.
Throughout the prairies, plains and deserts of the United States, tumbleweed has jumped into the paths of speeding motorists, choked canals and swimming pools, and caused floods and fires alike. In Rankin, Tex., tumbleweed driven by 98-m.p.h. winds piled up 10 feet deep on a Saturday in 1983, blocking state Highway 349 for seven hours and burying at least one car.
"It is probably the No. 1 nuisance weed in San Diego County," said Kathleen Thuner, county agricultural commissioner.
And Lloyd Andres, research leader at the U. S. Department of Agriculture Biological Control of Weed Laboratory in Albany, Calif., contends that tumbleweed is one of the top two problem plants in the state. "In Southern California, it might be the No. 1 nuisance weed," Andres said. "It certainly is along Interstate 5. In Northern California, you see more yellow star thistle."
According to county Deputy Agricultural Commissioner Carolyn Nielsen--who says she has been "chasing weeds, bugs and rodents" for eight years--"tumbleweed is just so awesome," posing a threat nearly year-round.
When it's growing in late winter and early spring, Nielsen said, it gets big enough to obscure intersections and roadways. "Another real problem is on airport runways," Nielsen said. "If it is allowed to grow, it can obscure the landing lights."
But the real danger comes in late August and early September, when mature weeds--which grow to many feet in diameter--dry out, snap off at the base and are tossed through the streets by hot Santa Ana winds.
"It's really disorienting to people when they they drive down the freeway and see this mammoth thing tumbling toward them, even if it doesn't weigh much at all," Nielsen said. "It also causes the same kind of traffic problems with airports."
Tumbleweed is not a problem for everyone. In 1956, a ditch full of it saved the life of an Idaho man whose car went out of control. The tumbleweed provided an effective cushion as the car rolled over 2 1/2 times down a 40-foot embankment. When the car stopped, the man was able to drive it out.
And a Walla Walla, Wash., woman created the Tumbleweed Tannenbaum in 1982, flocking and decorating tumbleweed bushes and selling them for $20 in her florist shop. Disposal was easy, she said at the time: "You just place the discarded weed in the backyard, and it will be gone the next windy day."
Although tumbleweed is the beloved prop in Westerns, from the silent movie "The Great Train Robbery" to "Santa Fe Trail" and "They Died With Their Boots On," the plant is not native to North America.
In fact--Audie Murphy, hold your ears--it came from the Soviet Union. Called the Russian thistle, the plant was brought to the United States in the late 1800s accidentally, hitchhiking along with shipments of imported grains. If it's Western at all, it comes from western Asiatic Russia, experts say.
Since its accidental arrival, the weed has been the focus of a concerted effort to get rid of it. In the 1970s, American scientists went to the Soviet Union to try to find natural insect enemies of tumbleweed and introduce them into the United States.
But worsening relations between the Soviet Union and the United States have sharply curtailed such research exchange programs, Andres said.
Andres did a great deal of work with two kinds of moths--the \o7 Coleophora parthenica \f7 and the \o7 Coleophora klimeschiella--\f7 which are indigenous to Pakistan as well as Russia. After the moths were brought here, they were distributed throughout California by the state Department of Transportation, which has the responsibility of keeping state-owned thoroughfares free of tumbleweed and other nuisance plants.
Theoretically, the moths' larvae bore into the branches and eat them, so the tumbleweeds collapse and are not a threat. But the experiment was generally a flop.
"It was a disappointment," said Dan Cassidy, landscape specialist for Caltrans. "But it did work well in San Diego and Imperial counties, and in the Coachella Valley."