Differential susceptibility of white fir provenances to balsam twig aphid

Abstract

Susceptibility of Oregon, California, Nevada, Utah, and Arizona provenances of white fir (Abies concolor [Gord. & Glend.] Lindl.) to crown injury caused by balsam twig aphid (Mindarus abietinus Koch.) was assessed in an experimental plantation in the central Sierra Nevada in California. Bud phenology was observed to explore relationships between flushing times and crown injury. Highest susceptibility occurred in the Oregon provenances, which represented natural populations intermediate between A. concolor and grand fir (A. grandis [Doug.] Lindl). Least susceptibility occurred in provenances from northern and central California, southern California, and western Arizona, representing A. concolor var. lowiana or var. concolor, or their intermediates. Moderate susceptibility occurred in var. concolor provenances from eastern Nevada and western Utah. Flushing times of provenances varied, but evidence that they influenced susceptibility to the aphid was scant.

Citation

Ferrell, George T. 1989. Differential susceptibility of white fir provenances to balsam twig aphid. Res. Note PSW-RN-403. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 4 p.