Mycorrhizal fungi associated with Festuca in the western United States and Canada

Abstract

Vesicular-arbuscular mycorrhizal infection and associated mycorrhizal fungi were examined for F. viridula, F. idahoensis, F. scabrella, F. thurberi, F. ovina and F. arizonica occurring in Festuca-dominated grasslands. All plants were mycorrhizal. Nearly all had mycorrhizal infection in 75% or more of their fine root length. Although levels of infection were consistently high, spore numbers were generally low. No differences in the degree of infection between Festuca spp. or habitats were observed. Eleven mycorrhizal fungi were identified and ranked by decreasing frequency as follows: Glomus fasciculatus, G. tenuis, Gigaspora calospora, Acaulospora laevis, Glomus macrocarpus var. macrocarpus, Glomus microcarpus, A. scrobiculata, Glomus mosseae, G. macrocarpus var. geosporus, Sclerocystis rubiformis and an unidentified Acaulospora sp. It was common to find 2 or more species infecting an individual plant. The mean number of fungal associates per community site ranged from 2.7 spp. for F. idahoensis to 5.0 spp. for F. arizonica. No evidence was found for specificity of any of the mycorrhizal fungi for any particular Festuca host.