June 24, 2023
We have been invaded! Troops of foreign plants have marched across local hillsides, and this is the season when they probe the defenses of gardens on our very doorsteps.
Yellow blooming mustard may create a colorful slope in the distance and may even look cheery on a barren patch in an urban area, but do not be deceived. Mustard plants are part of an evil botanical empire of ill effects. After crowding out native plants such as blue lupine and poppies, and depriving a diverse ecosystem of water and sunlight, these agents of destruction march onward, never satisfied with the ground they have already taken.
Some unwitting collaborators serve as fifth columnists, aiding and abetting by planting invasive exotics in residential landscapes. One such attacker is Pennisetum, varieties of which are sold in some nurseries. Gardeners are attracted by harmless sounding common names including “purple fountain grass” and “bunny tails.”
Cape ivy is another traitor, seeming to serve as a garden variety, but escaping when given an opportunity to cover and strangle chaparral vegetation. Similarly, artichoke thistle may tempt with beautiful blooms, but it quickly infests nearby land.
Caretakers of the Ronald Reagan Presidential Library & Museum in Simi Valley combat invading weeds in the spirit of the library’s namesake, who is credited in the library’s displays with fighting communism while preventing the destruction of direct warfare. Crews tending the grounds fight weeds without the destruction of massive herbicide application.
On June 1, as in previous years since 2011, the Reagan Library called in an allied species: goats. A local company, 805 Goats, brought a platoon of 100 goats, with shepherds and herding dogs keeping them focused on the fight.
Both Leslie Velez, outreach director for the Ventura Land Trust, and Tom Maloney, executive director of the Ojai Valley Land Conservancy, have also used goats on properties their organizations manage.
“In an area like the west slope of Harmon Canyon, where residences are nearby, we had to use goats,” Velez said. “The goats leave roots in place and that holds the soil, preventing erosion.”
Unfortunately, leaving roots in place means weeds will come back until volunteers with hand tools do the hard work of removing nonnatives one at a time, shoring up hillsides and planting native species. In the meantime, until the goats return, the crowded-out native plants get a fighting chance to compete.
“The key factors are timing, intensity and frequency of the disturbance — planned grazing, prescribed burning or mowing,” Maloney said. If those factors are dialed in, “grasslands most likely improve,” he said.
Goats are not a solution for everyone. The 805 Goats website says their minimum project size is 2 acres. Instead, herbicide use is sometimes necessary.
At the Ventura County Government Center, the General Services Agency “exclusively uses a citrus oil-based product to control weeds,” according to Patrick Squires, facilities manager. Approved by the federal National Organic Program, the natural herbicide is so effective, Squires’ major concern is to keep it from affecting adjacent, desired plants.
Generally, weed removal requires hand-to-root combat. Velez said the main tools are trowels, small rakes and fingers stuck deep into the ground to wrap around roots. Maloney added, “It helps if the area is seeded with natives after thatch is cleared.”
Of course, the benefit is not just to preserve native flora, which generally provide the best habitat for native fauna. Weeds pose another threat. They spread fire.
Two months ago, new rules issued by California Insurance Commissioner Ricardo Lara went into effect. To increase transparency in setting premiums, insurance companies must now inform clients of wildfire risks on their properties and suggest safety measures, such as weed clearance, that clients can take to avoid non-renewal of policies.
For those not at risk of non-renewal, taking these precautions may lower fire risk scores and reduce fire insurance costs. Consumers have the right to appeal risk scores, for example, by documenting their progress in the battle against weeds.
David Goldstein, an environmental resource analyst with the Ventura County Public Works Agency, can be reached at 805-658-4312 or email@example.com.