Skip to main content
U.S. flag

An official website of the United States government

Assessing the susceptibility of white fir to the fir engraver, Scolytus ventralis Lec. (Coleoptera: Scolytidae), using fungal inoculation

Informally Refereed

Abstract

A method of assessing susceptibility of white fir, Abies concolor (Gord. and Glend.) Lindl., by fungal inoculation was tested during an outbreak of the fir engraver beetle, Scolytus ventralis LeC., at Lake Tahoe, California, in 1987 through 1989.A total of 592 firs growing in six forest stands containing trees infested by the beetle were inoculated with the mutualistic fungi, Trichosporium symbioticum Wright.Six weeks later, reaction wounds were characterized by vertical length and resin concentration.After 2 years, 196 (33.1%) of the test firs had been killed by the beetle.Reaction lengths tended to be greater and resin concentrations lower in test firs that died than in those that survived, but predictive accuracy of the wound variables was inadequate on either an individual tree or a stand basis.On an individual tree basis, discriminant functions using either or both of these reaction wound variables a predictors produced overall percentages of correct classification little higher than would be obtained by predicting than all test firs would survive.On a stand basis, regression models using stand means for the wound variables and white fir basal area as predictors statistically explained more than 95% of observed variation in basal area of white fir killed, but another model using only basal area of white fir as a predictor performed nearly as well.

Citation

Ferrell, G.T.; Otrosina, W.J.; DeMars, C.J., Jr. 1993. Assessing the susceptibility of white fir to the fir engraver, Scolytus ventralis Lec. (Coleoptera: Scolytidae), using fungal inoculation. The Canadian Entomologist 125:895-901.
Citations
https://www.fs.usda.gov/research/treesearch/1054