- Author: Jeannette E. Warnert
Knowing the names of trees is a point of pride for many California Naturalists. So a walk among the diversity of oaks at the Pepperwood Preserve left many feeling humbled.
The three-hour excursion was part of the UC California Naturalist Regional Rendezvous in October at the 3,200-acre nature preserve nestled in the foothills between Napa Valley and Santa Rosa.
Excursion leader Steve Barnhart, academic director emeritus at Pepperwood, said there are 500 oak species in the world; 21 in California. But cohabitating on the rolling hills and valleys of the Golden State, many oaks have produced hybrids that combine...
Drought is decreasing but not defeating the pathogen that causes sudden oak death, according to a citizen science-assisted survey conducted this spring by a UC Agriculture and Natural Resources forest pathologist.
Results of the 2015 Sudden Oak Death Blitz survey reveal coastal mountain infestations in areas such as Big Sur (19% infection), the Santa Cruz Mountains (13% infection), and western Sonoma County (12% infection) remain high despite an overall decline in infection rates from 4.4% to 3.7% across California's 15 infested counties.
Sudden oak death (SOD) symptoms have been seen in Alameda, Contra Costa, Humboldt, Lake, Marin, Mendocino, Monterey, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano,...
Bill Tietje is a UC Cooperative Extension area natural resources specialist in the Department of Environmental Science, Policy and Management at UC Berkeley. He is based in San Luis Obispo.
UC Cooperative Extension's Master Gardeners have received many calls during the past few months concerning the poor condition of many California native oak trees, in both urban and rural landscapes. Many evergreen oaks, including coast live oaks, have brown leaves and thin foliage. Adding to the unattractiveness, a deciduous oak, the blue oak, dropped its leaves ahead of schedule. Although a tree may look unhealthy, it can recover.
Early leaf drop is a deciduous tree's adaptation for conserving water that it otherwise would...