Widespread morbidity and mortality of Juglans nigra has occurred in the western USA over the past decade. Tree mortality is the result of aggressive feeding by the walnut twig beetle (Pityophthorus juglandis) and subsequent canker development around beetle galleries caused by a filamentous ascomycete in genus Geosmithia (Ascomycota: Hypocreales). Thirty-seven Geosmithia strains collected from J. californica, J. hindsii, J. major and J. nigra in seven USA states (AZ, CA, CO, ID, OR, UT, WA) were compared with morphological and molecular methods (ITS rDNA sequences). Strains had common characteristics including yellowish conidia en masse, growth at 37 C and absence of growth on Czapek-Dox agar and belonged to a single species described here as G. morbida. Whereas Geosmithia are common saprobes associated with bark beetles attacking hardwoods and conifers worldwide, G. morbida is the first species documented as a plant pathogen.

Institute of Microbiology of the ASCR v v i Vídeňská 1083 142 20 Praha 4 Czech Republic

References provided by Crossref.org

Characterization and microsatellite marker development for a common bark and ambrosia beetle associate, Geosmithia obscura

Geosmithia Species Associated With Bark Beetles From China, With the Description of Nine New Species

Geosmithia associated with hardwood-infesting bark and ambrosia beetles, with the description of three new species from Poland

Fungal metabolic profile dataset was not influenced by long-term in vitro preservation of strains

Vector affinity and diversity of Geosmithia fungi living on subcortical insects inhabiting Pinaceae species in central and northeastern Europe