Hillside Mustard Too Tenacious to Weed Out : Environment: Large swaths of Cheeseboro Canyon are overrun with non-native plant. Eradication program shows little results so far.


The lush fields of yellow flowers blanketing the county’s hillsides might be a pleasant distraction for motorists on the Ventura Freeway tired of contemplating the bumper in front of them.

But for the National Park Service, mustard is just one tough weed.

Since December, 1991, the Santa Monica Mountains National Recreation Area’s fire-management team has been trying to eradicate mustard by setting fires in parts of Cheeseboro Canyon, where acres and acres are overrun with the non-native plant.


Despite their efforts, the mustard just keeps coming back, practically a thicket of six- and seven-foot stalks, pushing aside native plants wherever it roams.

“It’s funny,” one hiker said, pausing on a trail in Cheeseboro Canyon. “I think ever since they started prescribed burns, they’ve had more mustard then ever.”

Fire management officer Ishmael Messer said that without the burn program, areas such as Cheeseboro Canyon would eventually be overtaken by mustard.

“It’s pervasive and it’s very adaptive,” he said.

He admitted that the eradication program, still in its experimental stages, shows little results so far.

“The visual perspective is that there’s a lot of mustard out there, and that’s true,” Messer said.

But he said the park service has measured some minute reductions in mustard plant populations and simultaneous small gains among grasses such as stipa, a native plant that grows in clumps.

The park service began its eradication efforts in late 1991 by burning a 200-acre patch on Modelo Trail. In June, it moved to the middle of the canyon, burning 500 acres.

Now the hills about a mile back on Modelo Trail look like a pointillist’s painting come to life, with millions of yellow dots swaying in the wind.

Part of this year’s healthy mustard crop can actually be attributed to the prescribed fires. The plant initially responds well to such disturbances, Messer said. Seedbeds probably were full when the fire came through last year, and they stay safe unless the flames burn extremely hot.

“There’s no way the fire can consume all the seedbed in the ground,” Messer said. “The idea is to decrease it enough so that we can stop the plant from spreading. But it’s going to take a long time for that to happen.”

Naturalist Milt McAuley, author of “Wildflowers of the Santa Monica Mountains,” said the park service’s battle against mustard is a losing one.

“The park service will find out to their dismay that it won’t work,” McAuley said. “You can do what you want to mustard, but next year, it’s going to come back.”

He cited areas in Topanga State Park in which two natural fires and two prescribed fires failed to eradicate the plant.

“Some of the biggest mustard patches in the park are in those burn areas,” McAuley said. “Mustard is overwhelming us in many areas. . . . It’s bad news. But you can’t get rid of it.”

There are 43 species of mustard to be found in the region, but by far the most prevalent is black mustard, or Brassica nigra , which has been giving the hills behind the city of Ventura a yellow-capped appearance for the last two weeks. Although some types of mustard are native, black mustard is not.

The tales about mustard’s California origins are almost as varied as the number of species. The most often told and certainly most romantic story is that priests, traveling with Spanish invaders in the 1760s, brought bags of mustard with them on a journey to Monterey. Along the way, they sprinkled seeds, hoping that when they returned to Mexico the following spring, the flowers would have bloomed and could show them the way.

Another story is that sailors from Mediterranean countries brought with them mattresses stuffed with dry vegetation from home. By the time they arrived in California, the mattresses were moldy and matted down. They brought them to shore, pulled out the old stuffing to change it and thus sowed the seeds.

McAuley said the version he believes is that people scattered the seeds in burn areas during the 1950s and ‘60s, hoping to rejuvenate the vegetation.

All mustard is edible. The leaves taste sweet for about 10 seconds, then burst into a spicy mustard flavor.

But Bob Brendler, with the Ventura County Farm Advisory Office, does not know anyone who commercially grows or harvests mustard.

“Most of it is just viewed as a noxious weed,” Brendler said. “It takes up space and soil nutrients.”

One historian, Joseph Russell, writes in his book “Cattle on the Conejo” that early farmers in the area did harvest black mustard, planting it in the same field as oats. According to Russell, mustard seed crops were an important contribution to the area’s economy.

Mustard is made in Ventura County today--in fact, the world’s yearly production of 30 million jars of gray poupon is blended at Nabisco’s Oxnard plant, Nabisco spokesman Mark Gutsche said. But the brown mustard seeds the company uses are imported from northwestern Canada.

“There’s no connection between our mustard and those pretty yellow flowers you see by the roadside,” Gutsche said.

If there were, the park service might have a market for its unwanted crop. Instead, it intends to continue trying to kill the vegetation, with a 700-acre burn planned for Cheeseboro Canyon in late May or early June. After that, rangers will inspect and decide when to schedule the next burn.

“It’s difficult,” Messer said. “The Santa Monica Mountains have been so highly manipulated by human beings. It’s hard for us to determine what actually does belong in Cheeseboro Canyon. But what we’re shooting for is to bring back that oak savannah grassland.”

McAuley has a suggestion for the park service on how to achieve that goal.

“Maybe they should send a bunch of people out there to make sandwiches,” he said.