First report of an Armillaria root disease pathogen, Armillaria gallica, associated with several new hosts in Hawaii.
In August 2005, rhizomorphs and mycelial bark fans of genet HI-4 were collected from dead or declining, mature trees of introduced Monterey pine (Pinus radiata) on the southern flank of Mauna Kea, Hawaii, USA. In March 2008, three additional genets (HI-11, HI-13 and HI-16) were collected as rhizomorphs at a site named Púu Láau (west slope of the Mauna Kea Forest Reserve area, approximately 20 km west-northwest of the HI-4 collection). These genets were collected from apparently healthy loblolly pine (Pinus taeda) that were introduced, apparently healthy Sophora chrysophylla, dead and dying S. chrysophylla, and apparently healthy Methley plum (Prunus cerasifera × Prunus salicina) that was planted. All isolates were determined to have identical sequences in the intergenic spacer-1 rDNA region (GenBank accession no. DQ995357). Based on somatic paring tests against North American Armillaria tester strains and 99% nucleotide sequence identities to GenBank accession nos. AY190245 and AY190246, these isolates were identified as A. gallica. This is thought to be the first confirmed report of A. gallica in Hawaii, where it was found on S. chrysophylla, Monterey pine, loblolly pine and Methley plum.