Response of different white fir geographic provenances to Trichosporium symbioticum inoculation in California.
We inoculated the fir engraver (Scolytus ventralis LeConte) associated fungus Trichosporium symbioticum Wright onto 56 white fir (Abies concolor (Gordon & Glend.) Lindl. ex Hildebr.) trees planted in a common garden study near Camino, California, that represented five geographic provenances of this species. The objective was to determine if there is a differential lesion length response of white fir provenances with respect to provenance. We found a significant (P<0.019) difference between the provenances from Arizona and those of eastern Nevada origins 28 days after inoculation. There was a significant interaction between the two T. symbioticum isolates and season of inoculation. Fall inoculations tended to have smaller lesions than those in the spring but this varied by isolate in that the one from eastern Nevada tended to produce longer lesions in the spring (P=0.0001) whereas the isolate from the Camino plantation did not differ between spring and fall (P=1.000). There is evidence for genetic variability relative to white fir provenance lesion length in response to T. symbioticum inoculation, and in future studies, isolate variability should also be taken into account.