PROGRAMS :: Watershed Stewardship Project

Pleasants Creek landowners hear that Arundo removal is possible, with patience

Northern California watershed managers will be watching the Santa Ana River Watershed Authority's $20 million campaign against the bamboo-like weed Arundo with sharp interest. After nearly a decade of trying unsuccessfully to reclaim the banks of the river and its tributaries from the tenacious invader, the authority will soon launch a five-year eradication effort to clean up some 3,000 acres of river and creek banks.

In these views of Pleasants Creek taken in April 2002, new growth of native vegetation is beginning to re-establish itself following the removal of the invasive weed, Arundo donax, the previous fall.

"That's what we will be looking at if we don't start taking care of the problem that's developing with Arundo up here on Pleasants Creek," Ron Unger recently told a field meeting of landowners and resource officials gathered at Hoskins Ranch, along the creek near Winters. The meeting was co-sponsored by Community Alliance with Family Farmers and the Solano Resource Conservation District, partners in the Watershed Stewardship Project funded by CalFed.

Unger, a vegetative management specialist and restoration biologist for EDAW, Inc., said Arundo spreads rapidly via rhizomes that can grow up to 12 inches a day just below the soil surface. "They extend out of clumps at the base of the plant and those clumps will double in size every year," he said.

Properly known as Arundo donax, the plant originated in India, spread west to the Mediterranean region and arrived in California with early Spanish settlers. Today, Arundo can be found in most California waterways below 1,000 feet in elevation. In the 1920s, Arundo was widely used in southern California for streambank erosion control.

With canes that easily reach 30-40 feet tall in California's climate, Arundo takes control of the entire steamside environment as it out-competes native plants and proves inhospitable to birds, animals and fish that can find neither cover or sustenance in its dense growing clumps. Once established, Arundo sucks up tremendous amounts of water, Unger said, thereby placing further pressure on the state's most precious resource.

The sheer physical mass of dislodged Arundo clumps is another major problem the weed presents. "Some bridges in southern California have been washed out two and three times by Arundo canes and root masses piling up against them in high water flow conditions," he said. "It's also a severe fire hazard due to the waxy coating on the canes. It will burn even when it's green."

Unger said killing Arundo is a fairly simple, if lengthy, process. "It's important to use a systemic herbicide such as Roundup or Rodeo so that you're killing the roots as well as the canes. After it dies back, cut it down and re-spray any plants that re-sprout. You can get a 90-percent kill in the first year if you do it right," Unger said. Lower Putah Creek streamkeeper Rich Marovich said that herbicide timing and dosage is critical.

"Roundup is a systemic material and using too much can kill the plant so fast the material won't reach the roots and kill them too. A three-percent solution seems to be the most effective rate," he said. "Roundup will also work slower in cooler weather, which is good because it needs time to get to the roots. That means late fall and early winter is a very good time to begin treating Arundo infestations."