Colonization history, host distribution, anthropogenic influence and landscape features shape populations of white pine blister rust, an invasive alien tree pathogen.

White pine blister rust is caused by the fungal pathogen Cronartium ribicola J.C. Fisch (Basidiomycota, Pucciniales).

Identification of New Fungal Pathogens of Coast Live Oak in California.

A decline of coast live oak (Quercus agrifolia) has been observed throughout southern California. In this study, the identity and pathogenicity of non-Botryosphaeriaceae fungal species consistently recovered from necrotic tissues of branch and bleeding trunk canker samples from these locations were assessed. Species were identified morphologically and by comparison of the complete sequence of the internal transcribed spacer (ITS) of the ribosomal DNA to sequences available in GenBank.

First Report of Rust Caused by Puccinia psidii on Paperbark, Melaleuca quinquenervia, in California.

Infections by Puccinia psidii Winter were detected on Melaleuca quinquenervia (Cav.) Blake (paperbark, tea tree) during a regular inspection of a San Diego, California nursery in November 2010 by San Diego County inspectors. Urediniospore morphology, production of bright-yellow uredinia on both upper and lower leaf surfaces, DNA sequencing, and inoculation tests confirm the identity of the pathogen.

First Report of Bot Canker Caused by Diplodia corticola on Coast Live Oak (Quercus agrifolia) in California.

Sharp decline and mortality of coast live oak (Quercus agrifolia) has been observed in San Diego County, CA since 2002. Much of this decline has been attributed to a new pest in California, the goldspotted oak borer (GSOB, Agrilus coxalis) (1). Symptoms include crown thinning, bark cracking and/or peeling, patches of stain (1 to 10 cm in diameter), bleeding on the bole, and tree death and are most often observed on trees with a diameter at breast height (DBH) >30 cm.