The effect of Alectoria sarmentosa, Bryoria fuscescens, and Bryoria fremontii extracts and usnic acid on the growth of Gremmeniella abietina in vitro

The response of internal and external extracts of fresh arboreal lichens, Alectoria sarmentosa, Bryoria fuscescens and Bryoria fremontii, and commercial usnic acid extracted from Usnea spp. and Cladonia spp. on the growth of the Ascomycetous Gremmeniella abietina types was studied in vitro. Neither internal and external extracts of the three lichen nor usnic acid had strong inhibitive effect on the growth of either type A or B of G. abietina. A slight stimulative effect due to the extracts was, however, detected: type B (isolate 12) grew faster on almost all media than type A (isolate 11), but great variation within isolates of both types existed suggesting that different types of G. abietina may have different responses to chemicals. Keywords: Gremmeniella abietina, Alectoria sarmentosa, Bryoria fuscescens, Bryoria fremontii, usnic acid, lichen toxicity.