Invasive Species Compendium

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Abstract

Variation of pathogenicity and virulence of isolates of Armillaria ostoyae on eight tree species.

Abstract

A total of 13 isolates representing 10 genotypes of A. ostoyae, obtained in northern New Mexico, USA, from Pinus ponderosa, Abies concolor, Pseudotsugamenziesii, Pinus strobiformis, Picea pungens and Populus tremuloides were used to inoculate seedlings of these hosts and Larix occidentalis and Pinus contorta var. latifolia. At 18 months, there were no significant differences (P>0.05) in mortality among the 8 hosts or in virulence across all isolates, except for one isolated from P. pungens, which failed to infect any trees. After 3 growing seasons (30 months), significantly more (P<0.05) P. contorta var. latifolia were infected than either A. concolor or P. menziesii. Pinus ponderosa, the dominant species in this region, did not differ significantly from either of the exotic species (L. occidentalis and P. contorta var. latifolia) in susceptibility to infection or mortality. Populus tremuloides was significantly (P<0.05) more tolerant than conifers, being frequently infected, but rarely killed. The ability of an isolate to incite disease was highly correlated with its production of rhizomorphs (r=0.94, P<0.01). Across all fungal isolates and hosts, except P. tremuloides, the order of the isolate's ability to incite disease matched its order in killing hosts.