Cross pathogenicity of Neofusicoccum australe and Neofusicoccum stellenboschiana on grapevine and selected fruit and ornamental trees: Neofusicoccum australe and N. stellenboschiana cross pathogenicity

Abstract

Neofusicoccum australe is one of the most important Botryosphaeriaceae pathogens occurring on fruit and vine crops. This fungus was recently taxonomically reassessed, identifying N. stellenboschiana as a separate species. Previous pathogenicity studies used N. stellenboschiana and N. australe isolates as N. australe, so assessment of the pathogenicity of these two species on grapevine and other hosts was required. A pathogenicity trial was conducted on detached shoots of grapevine, plum, apple, olive and Peruvian pepper tree. Shoots were individually inoculated with 11 N. australe and eight N. stellenboschiana isolates originally isolated from grapevine, plum, apple, olive, Peruvian pepper and fig. Both species formed lesions on all five hosts and were re-isolated 5 weeks post-inoculation. In general, the largest lesions were formed on plum and smallest on Peruvian pepper. Isolate host origin did not influence ability to cause lesions on other hosts. Isolates of N. australe and N. stellenboschiana differed in virulence on the various hosts, ranging from those that caused the largest lesions, a group causing intermediate lesions, and another causing lesions similar to uninoculated controls. The study demonstrates that N. australe and N. stellenboschiana isolates originating from various fruit hosts can infect alternative hosts including grapevine and other major fruit crops.