PITCH CANKER DISEASE OF PINUS RADIATA
LD DWINELL 1, D ADAMS 2, JJ GUERRA-SANTOS 3 and JRM AQUIRRE4
1USDA Forest Service, Athens, Georgia, USA, 2California Department of Forestry, Davis, California, USA,3 Instituto de Fitosanidad, Montecillo, Mexico, and 4 Departamento de Agricultura, Bilbao, Spain
Background and objectives
Results and conclusions
Pitch canker was unknown in California until disease outbreaks on planted Monterey pine were found almost simultaneously at 3 widely separated geographical locations. Since 1986, surveys found the disease extends from Mendocino County to San Diego; however, the disease is most severe on the central coast of California. In the past few years, the disease has become established in natural populations of Monterey pine. The causal fungus is a wound parasite and a number of insect species are involved in the disease complex. Because P. radiata originates from three mainland native populations in California, pitch canker in these populations is a severe threat to the Monterey pine genetic resource worldwide.
In Mexico, pitch canker has been reported on a number of native and introduced pine species. In 1992 , the disease was observed in a radiata pine plantation near Amecameca in the State of Mexico. Shoot dieback in the upper crown of the 20-year-old radiata pines was the main symptom. Sporodochia of the pitch canker fungus were found on diseased shoots.
Pitch canker was first observed in Europe in 1997 in the autonomous community of País Vasco (Basque Country) in northern Spain. The disease is causing the mortality of radiata pine seedlings in bare-root nurseries. Pitch canker has not been confirmed in radiata pine plantations. Surveys are being conducted to determine the incidence and severity of the disease in País Vasco.
Since pitch canker was first described in 1946, the parameters of the disease have been constantly changing. Besides the United States, Mexico, and Spain, pitch canker has been reported in Haiti on P. occidentalis and Japan on P. lunchuensis. In South Africa, the pathogen induces a root rot of containerized-P. patula. Pinus radiata is the most widely planted pine in the world. The introduction of the disease into other countries with extensive radiata pine plantations, such as Chile, New Zealand and Portugal, could be disastrous to forest products industries.