The fungal pathogen Taphrina caerulescens was isolated from leaves of water oak (Quercus nigra) exhibiting symptoms of oak leaf blister. Healthy leaves were inoculated with a suspension of cells from pure culture in order to examine the infection process. Scanning electron microscopy was used to monitor budding of T. caerulescens cells, formation of germ tubes, and indirect penetration of leaf tissue through stomata, which occurred within 48 h post-inoculation. Direct penetration was not observed.
Taylor, Josephine and Birdwell, Dale O., "A Scanning Electron Microscopic Study of the Infection of Water Oak (Quercus nigra) by Taphrina Caerulescens" (2000). Faculty Publications. 88.