Maximum residue limit of fungicides inhibits the viability and growth of desirable non-Saccharomyces wine yeasts: Maximum residue limit of fungicides inhibits yeasts

Background and Aims Fungicides used against the mould Botrytis cinerea can also non‐specifically affect indigenous yeasts important for the development of complex wine aroma. Our aim was to determine the minimal inhibitory concentration of the fungicides iprodione, pyrimethanil and fludioxonil plus cyprodinil for 109 yeasts of the grape berry microbiota. Methods and Results We measured the respiration activity of yeasts, changes in growth kinetics and adenosine triphosphate production. Fungicide tolerance may be a conserved feature within the yeast's genera, however, some heterogeneity between isolates remains. The viability and growth of 15 beneficial isolates were inhibited by fungicides at a residue concentration below the maximum permitted residue limits. These isolates belonged to the yeast species: Metschnikowia pulcherrima, Pichia kluyveri, Hanseniaspora uvarum and Bulleromyces albus. Furthermore, isolates of typical spoilage yeasts, such as Dekkera bruxellensis, Meyerozyma guilliermondii and Pichia membranifaciens, were found to be tolerant of a concentration of fungicides greater than that recommended for application by the suppliers. Conclusions Fungicide residues hindered the viability of desirable isolates and promoted the growth of several spoilage isolates and thus may have a negative impact on wine aroma. Significance of the Study For spontaneous fermentations the application of fungicides in the vineyard could add to the seasonal fluctuations of aroma and to the development of off‐flavours.