Production of Neofusicoccum species conidia and their pathogenicity on wounded and non-wounded blueberry shoots

Abstract

Pycnidial and conidial production by isolates of the four main Neofusicoccum species associated with blueberry in New Zealand was investigated. Pycnidia developed after 8 days on mycelial-inoculated detached green shoots. Conidial ooze was observed after further incubation for 12 h under high relative humidity at 25°C. Numbers of oozing pycnidia and conidial numbers were generally low, but were significantly affected by isolate and species. Neofusicoccum ribis and N. parvum produced slightly more pycnidia and conidia compared with N. luteum and N. australe. Inoculation of non-wounded and wounded attached green shoots with either N. ribis or N. australe conidia showed that, 14 days after inoculation, lesions developed in wounded shoots only, with N. ribis (58.8 mm) producing longer lesions than N. australe (29.8 mm). Neofusicoccum ribis and N. australe were re-isolated beyond the lesion, with pathogen progression being significantly greater for wounded (47.1 mm) compared with non-wounded shoots (30.4 mm).