United States Forest Service California 

Department of Agriculture Pacific Northwest Region Department of Forestry 

Forest Health Highlights In California – 2002 

August 2003

 Insects

The winter of 2001-2002 was dry in southern California. The San Bernardino Mountains and 

the Peninsular Ranges received historically low precipitation in what was the fourth consecutive 

year of drought. The result has been elevated vegetation mortality – pines, white fir, cedar and 

chaparral – that affects over 151,000 acres in the San Bernardino Mountains with tree mortality 

of 10% or more on 114,000 acres. The magnitude and extent of mortality has produced fuels 

that pose major threats to life and property, ecosystem structure, function and long-term 

sustainability. Losses include high value landscape trees and aesthetics (Fig. 1). 

Although some tree mortality was locally significant in northern California, mortality was low 

region-wide relative to past droughts. Should the winter months of 2003 prove to be dry, 

increased tree mortality in northern California is anticipated. 

Populations of defoliating insects were variable. The fruittree leafroller (southern California) 

and lodgepole pine needleminer (Yosemite National Park) remained high. The fall webworm 

declined and populations of the California budworm remained low. Few gypsy moths were 

trapped by the California Department of Food and Agriculture. Long unreported, the Pandora 

moth appears to be in the initial stages of outbreak in Jeffrey pine on the Inyo National Forest. 

Figure 1: Pine mortality in the 

summer and fall of 2002, north 

shore of Lake Arrowhead, San 

Bernardino Mountain, California. 
 Diseases

New pitch canker infections continue to occur within the 18 counties of the Zone of Infestation. 

Rate of spread this past year may be slower as compared to earlier years in areas where the 

disease is well established. However, in stands where the disease has recently become 

established, incidence and severity are increasing rapidly. 

Sudden Oak Death: Isolation of Phytophthora ramorum from redwood, Douglas-fir and canyon 

live oak brought he total number of known native species affected in California to 22. The 

number of infected counties is now 12 with the addition of Humboldt and Contra Costa 

Counties. The confirmation of P. ramorum on the Los Padres National Forest near Big Sur is 

the first report from a National Forest. All confirmations remain within 50 miles of the Pacific 

Ocean. 

A second, previously undescribed species, P. nemarosa, is occasionally isolated from lethal 

cankers on tanoak and coast live oak and from foliar lesions on tanoak and California laurel. 

In forest settings it is usually associated with death of single trees rather than expanding 

patches of mortality characteristic of P. ramorum. 

Port-Orford-cedar root disease continues to expand in the upper Sacramento River Canyon 

and cause tree mortality. The southern extent of white pine blister rust has now been 

established in the area of Breckenridge Mountain on the Sequoia National Forest. 

 Animal Pests

Damage to trees was reported from 25 counties in California. A variety of species were 

involved with pocket gopher, black bear, deer, woodrats and tree squirrels being the most 

troublesome in terms of acres affected. 

 Contacts and Additional Information

If you have questions about forest health in California, please contact: 

John Dale Jesse Rios 

USDA Forest Service, Pacific Southwest Region California Department of Forestry 

State and Private Forestry 1416 Ninth Street 

1323 Club Drive Sacramento, CA 95814 

Vallejo, CA 94592 jesse_rios@fire.ca.gov

jdale@fs.fed.us (916) 653-8957 

(707) 562-8915 

Contributors: 

Alison Nelson 1 John Dale 1 

Kathy Sheehan 1 Jesse Rios 2

1 US Department of Agriculture, Forest Service

2 California Department of Forestry

R6-NR-FID-TP-08-03