Simi Brush Fire Is Called Season’s Worst : Emergencies: The blaze, described as suspicious, destroys more than 522 acres. No homes were damaged.

A suspicious fire that began Wednesday afternoon in a Simi Valley mustard field blossomed into Ventura County’s worst brush fire of the season, consuming more than 522 acres of vegetation before firefighters brought it under control.

Thick, 5-foot-tall brush near the Runkle Ranch caught fire about 2:30 p.m., sending flames to within 200 feet of homes and pushing a pall of gray smoke up over the southeastern part of Simi Valley on 10-m.p.h. winds.

While helicopters and air tankers bombed the area with fire retardant, 322 firefighters from Ventura and Los Angeles counties and the California Department of Forestry moved over the rough terrain on foot.

The crews cut firebreaks in the dense thickets and set backfires, deliberately burning brush that otherwise could have threatened about 500 children and teen-agers attending summer camp at the Brandeis-Bardin Institute nearby.

Flames devoured brush within 200 yards of buildings at the campus, but were kept at bay by a barren swath of ground that had been cleared of brush earlier in the summer.

“This is the worst brush fire of the season,� said Bill Reynolds, a spokesman for the Ventura County Fire Department.

The single blaze Wednesday consumed more than all the brush fires in Ventura County so far this season, which previously had totaled 188 acres since Jan. 1, Reynolds said.

Anxious residents of a nearby housing development watched the line of the fire sweep across the fields away from their homes. While some viewed the flames through cameras and binoculars, others readied garden hoses in case a change in the wind brought the fire closer.

Lisa Tepfer, 34, and her two sons watched the fire’s progress from outside their Beachnut Avenue home, about two blocks from the fire’s point of origin.

“When I came home and saw it, I was worried because of what happened last time,� Tepfer said. “We had a brush fire a few years ago that was right behind the houses, and they had to evacuate people. I wish they would put it out.�

Others remained calm.

“I wasn’t worried,� said Don Parker, 33. “We get brush fires out here about once a year. It’s good because it gets rid of the brush.�

Firefighters walked through clearings near the homes, setting backfires in the brush with the bright pink flames of magnesium road flares to deprive the main fire of fuel.

The fire was not nearly as dangerous as it could have been, thanks to high humidity, calm winds and “an aggressive weed-abatement program� mandated by Ventura County, said county firefighter Wayne Ferber.

The county requires property owners to keep land clear of weeds up to 100 feet from any structure.

The penalty for not complying is stiff. If the property owner fails to clear the area, the county Fire Department has the work done by a contractor and then bills the owner for the cost of the work, plus a $221 administrative fee, Reynolds said.

“What we want is no more than a 3-inch stubble� in the cleared area, he said.

By 7 p.m., firefighters had cut a perimeter around the blaze, calling it fully contained. They said the fire was fully extinguished by 9 p.m., but left 15 firefighters on the scene overnight to patrol the area for the resurgence of any hot spots.

Meanwhile, investigators began sifting through charred brush in an effort to learn how it started.

“I would say it’s person-caused,� said Peter Cronk, investigator-specialist for the Ventura County Fire Department. “It’s definitely suspicious, I’m leaning toward that.�

The fire began a few feet off of a dirt road extending from Sequoia Avenue, where only motorcyclists, bicyclists and pedestrians venture, Cronk said.

There was no evidence of downed power lines or fireworks, and humidity was too high for a cigarette to have caused the fire--leaving only backfire from a motorcycle or arson as a possible cause, Cronk said.

Times correspondent Maia Davis also contributed to this story.