Association of Armillaria root disease with mountain pine beetle infestations on the Black Hills National Forest, South Dakota

Examination of a random selection of 63 ponderosa pine stands on the Black Hills National Forest revealed a high incidence of both Armillaria root disease , caused by Armillaria mellea (Vahl.Fr.), and mountain pine beetle , Dendroctonus ponderosae Hopk .,;89 and 79 percent, respectively.The incidence of mountain pine beetle was the same for the northern and southern Black Hills .The incidence of Armillaria root disease was higher in the northern (93.1 percent) than the southern Black Hills (85.3 percent); however, this difference was not significant.A significant (p=.10) association between mountain pine beetle and Armillaria root disease was found in the northern, but not in the southern Black Hills.