Factors influencing virulence and conidial production of Neofusicoccum species on grapevine shoots

Abstract

Botryosphaeriaceae species are acknowledged as important wound pathogens of grapevines worldwide but reports as to the relative pathogenicity of species have varied. This study showed that the multiple vineyard isolates of Neofusicoccum luteum and N. parvum tested all caused disease of different grapevine stem tissues, but with great variation in symptoms and conidial release between isolates of each species. Overall, N. luteum caused longer lesions and produced more conidia than N. parvum on detached soft and semi-hard green shoots and on soft shoots of potted grapevines as well as on hard shoots of mature vines. With Sauvignon blanc, longer lesions and more conidia were produced on semi-hard green shoots and trunks of potted vines and on semi-hard green shoots of mature vines, than with Pinot noir. All isolates of N. luteum and N. parvum released conidia from stem lesions at all temperatures (10–25 °C) and RH (80–100%) tested, with most isolates releasing greatest numbers in high RH (~100%) and temperature (25 °C). This study showed that the two most commonly found species in New Zealand, N. luteum and N. parvum, were able to infect grapevine tissues and produce conidial inoculum under the temperatures and humidities commonly found in New Zealand vineyards.