Baskarathevan, JJones, ElizabethJaspers, MRidgway, H2024-09-272023-05-242023-04-232023-05-040042-7500M5VQ9 (isidoc)https://hdl.handle.net/10182/17657Genetic diversity and virulence variability of Diplodia mutila isolates recovered from grapevines in New Zealand were investigated. The universally primed PCR (UP‐PCR) and vegetative compatibility group (VCG) methods were used to investigate the genetic diversity. Pathogenicity tests with ‘Sauvignon Blanc’ detached shoots and potted vines were used to determine the virulence diversity. UP‐PCR analysis determined eight genetic groups of D. mutila with 70% of the population within one group. Phylogenetic analysis also determined that New Zealand isolates were more closely related to Australian isolates than Californian isolates. Vegetative compatibility grouping analysis placed the isolates into three VCG groups with 57% of isolates belonging to all three VCGs. Vegetative compatibility reactions were observed among isolates, but this was not correlated with the genetic clustering. Virulence assays proved that all isolates tested were pathogenic on grapevine stems. Differences in necrotic lesions lengths caused by D. mutila isolates were identified, indicating different virulence levels among isolates, however, no relationship was found between the genetic groups and the virulence. The results of the study indicated movement of D. mutila isolates between nurseries, vineyards, and other sources in New Zealand. This information will inform control strategies to limit the further spread of this pathogen into vineyards in the same region or new regions.pp.85-96en© 2023 The authors.anastomosisBotryosphaeria stevensiiBotryosphaeriaceaeDiplodia mutilapathogenicityvegetative compatibility groupVitis viniferaJournal Article10.5073/vitis.2023.62.85-962367-4156ANZSRC::300101 Agricultural biotechnology diagnostics (incl. biosensors)ANZSRC::300803 Horticultural crop improvement (incl. selection and breeding)ANZSRC::310802 Plant biochemistryANZSRC::300805 Oenology and viticultureANZSRC::300804 Horticultural crop protection (incl. pests, diseases and weeds)ANZSRC::3001 Agricultural biotechnologyANZSRC::3008 Horticultural productionANZSRC::3108 Plant biologyhttps://creativecommons.org/licenses/by/4.0/Attribution