Genetic diversity of B otrytis in N ew Z ealand vineyards and the significance of its seasonal and regional variation

Species‐ and population‐specific differences in fungicide resistance and aggressiveness within B otrytis makes basic data on genetic diversity important for understanding disease caused by this fungus. Genetic diversity of B otrytis was surveyed between 2008 and 2012 from grapes from five N ew Z ealand wine‐growing regions. A total of 1226 isolates were gathered from symptomless flower buds at the start of the growing season and 1331 isolates from diseased fruit at harvest. Two species were found, B . cinerea and B . pseudocinerea . B otrytis pseudocinerea was common in both A uckland vineyards sampled, and infrequent elsewhere. However, even in Auckland, it was rarely isolated from diseased fruit. The presence of the B oty and F lipper transposons was assessed. Isolates with all four transposon states (Boty only, Flipper only, both Boty and Flipper, no transposons) were found for both species. Both vineyards in the A uckland region had high numbers of Flipper‐only isolates at flowering; both vineyards from the Waipara region had high numbers of Boty‐only isolates at flowering. Most isolates from diseased fruit at harvest contained both transposons. These observations suggest that B . pseudocinerea , and isolates with one or both of the transposons missing, may be less aggressive than B . cinerea , or than isolates with both transposons present. Two clades were resolved within B . pseudocinerea , only one of which has been reported from European vineyards. Phylogenetic diversity within B . cinerea in N ew Z ealand was similar to that known from E urope, including isolates that appear to match B otrytis ‘ G roup S ’. The taxonomic implications of this genetic diversity are discussed.