The dynamics of an introduced pathogen in a native Monterey pine (Pinus radiata) forest

The plant pathogenic fungus, Fusarium circinatum, is the cause of a major epidemic of pitch canker in urban forests of Monterey pine (Pinus radiata) in California. This pathogen is now also well established in all three mainland, native populations of Monterey pine where it causes conspicuous branch die-back and, frequently in association with native bark beetles, increased tree mortality. In the present study, permanent plots were established on the Monterey peninsula to characterize the severity and progress of pitch canker in the largest of the native P. radiata populations. The results indicate that the disease is significantly more severe, and is progressing more rapidly, in managed stands than in the wildland areas. Furthermore, the disease is progressing significantly faster in the coastal zone than in more inland locations. # 2002 Elsevier Science B.V. All rights reserved.