Type: report

Article abstract: To address the threat that exotic, invasive plant species pose to native ecosystems, the Nature Reserve of Orange County (NROC) allocated approximately $260,600 in 2008 for the control of several exotic plant species of management and monitoring concern in the Orange County coastal subregion NCCP/HCP (The Natural Communities Conservation Plan & Habitat Conservation Plan). Exotic plant species targeted for control include artichoke thistle (Cynara cardunculus), garland chrysanthemum (Chrysanthemum coronarium), veldt grass (Ehrharta calycina), tree tobacco (Nicotiana glauca), castor bean (Ricinus communis), and pampas grass (Cortaderia selloana). Exotic plant management entailed prioritizing areas for treatment and controlling targeted exotic species through herbicide application. Treatment areas included Laguna Coast Wilderness Park (Emerald Canyon, Willow to Big Bend, north of SR 73 and Laguna Creek), Aliso and Wood Canyons Wilderness Park (AWCWP), Buck Gully, the University of California Irvine Ecological Reserve (UCI), City of Irvine Southern Open Space Preserve (North Laguna Canyon, Shady and Bommer Canyons, Bonita Canyon, Muddy Canyon, No Name Ridge and Quail Hill), El Toro Ecological Reserve, Whiting Ranch, and Crystal Cove State Park (CCSP). Treatment for the program began on March 10, 2008 and ended June 2, 2008. In total, treatment required 50 days, with multiple contractors working simultaneously (Nakae 44 days; Nature's Image 11 days; PRG 21 days), and comprised over 2,3451 acres of occupied habitat. Prior to monitoring and treatment, sites with potential nesting habitat were surveyed for two species of concern, the California gnatcatcher (Polioptila californica californica) and cactus wren (Campylorhynchus brunneicapillus). Sensitive species maps were also consulted to avoid impacting additional native plant and wildlife species of concern. Veldt grass was treated with the monocot selective, post-emergent herbicide Envoy in solution with Tripleline (an adjuvant enhancing herbicide performance). Artichoke thistle was treated with the post-emergent, broad-leaf selective herbicide Transline (chlorpyrid). Artichoke thistle at the University of California Irvine Ecological Preserve was treated with the non-selective glyphosphate Roundup-Pro. Garland chrysanthemum was treated with Roundup-Pro and Transline (at El Toro). Tree tobacco and castor bean were treated with Garlon 4 with the activator-surfactant Oranj-All