An initial genetic characterisation of the grape powdery mildew (<i>Erysiphe necator</i>) in New Zealand associated with recent reports of the sexual stage

Abstract

The asexual form of the grape powdery mildew Erysiphe necator has been present in New Zealand for over 100 years In 2013 the sexual stage was reported for the first time in vineyards in Hawkes Bay associated with increased disease issues This paper presents an initial genetic analysis of New Zealand populations compared to known populations overseas and tentatively identifies two haplotypes new to New Zealand Initial analysis of matingtype ratios indicates only one of these haplotypes is sexually reproducing A better understanding of the fundamental character of the New Zealand populations of Erysiphe necator is needed before an accurate assessment can be made of the practical impact that the introduction of the sexual stage has had on disease incidence and control