Isolation and axenic culture of poplar rust

Abstract

Surface-sterilized leaf pieces of black cottonwood (Populus trichocarpa) leaves centered on uredial infections of Melampsora occidentalis Pers. were placed, pustule side up, on a defined, agar-based medium. After 4 months the fungus became established on the medium. Axenic colonies, some of which produced urediospores, were established by transfer to fresh medium and were capable of reinfecting excised leaf pieces of the host. The technique bypasses germling development in vitro. This is the first report of the axenic culture of Melampsora occidentalis.