The sensitivity of yeasts and yeasts-like fungi to copper and sulfur could explain lower yeast biodiversity in organic vineyards

International audience; Although differences in yeast biodiversity have often been found between vineyards subjected to organic protection or conventional protection, little is known about the effect of copper and sulfur fungicides (the only fungicides allowed in organic farming) on yeast populations. The sensitivity to copper and sulfur of 158 yeast isolates of seven different species (Aureobasidium pullulans, Hanseniaspora guilliermondii, Hanseniaspora uvarum, Metschnikowia sp., Pichia membranifaciens, Saccharomyces cerevisiae and Starmerella bacillaris) was evaluated. The species Aureobasidium pullulans and Starmerella bacillaris appeared to be more resistant to copper than the other species tested. The species Aureobasidium pullulans, Hanseniaspora guilliermondii and Metschnikowia sp. had the highest sulfur resistance. Thus, only isolates of the species Aureobasidium pullulans exhibited high resistance to both antifungal agents. These results may explain the lower diversity of yeasts present on berries and the strong dominance of the species Aureobasidium pullulans for vineyards protected by copper or sulfur-based fungicides compared to other vineyards reported by several studies.