Abstract
Aureobasidium pullulans is a yeast-like fungus found on the surface of the grape berries that has been proven to act as a biocontrol agent for the management of grey mould disease caused by Botrytis cinerea. In this work, an indigenous strain of A. pullulans isolated from grape berries and selected according to the in vitro activity against B. cinerea, was used in vineyards of the winery where it originated, in comparison with a commercial product containing two A. pullulans strains with the aim of assessing its effectiveness as a biocontrol agent. The experimental design included daily meteorological data registration and the early defoliation of grapevines as treatments. The monitoring of A. pullulans strains on grape berries by plate counts and molecular methods as well as of B. cinerea symptoms on grape bunches was performed in the different trials from the end of flowering to the harvest time. Results highlighted that although no significant differences (p < 0.05) in the occurrence of B. cinerea were detected according to different treatments, the mean incidence of symptomatic berries ranged from 7 to 16%, with the lowest values recorded in bunches treated with the indigenous A. pullulans strain. The efficacy of the biocontrol agent was affected more by meteorological conditions than the defoliation practice.
Highlights
Aureobasidium pullulans is an oligotrophic, saprophytic and polymorphic yeast-like fungus naturally present in association with the endophyte populations in the phyllosphere and carposphere of various species of plants including both diseased and healthy grapevines [1,2]
A. pullulans has been exploited as a biocontrol agent for the management of Botrytis bunch rot (BBR) caused by the fungus Botrytis cinerea, and called grey mould, which is responsible for significant economic damage in vineyards and the postharvest decay of table grape [1,11,12]
The molecular biotyping of the A. pullulans isolates performed by RAPD-PCR with the primer P4, revealed the presence of 58 strains (Table 2) confirming the high polymorphism reported for this species by other authors [10,20,31]
Summary
Aureobasidium pullulans ( known as black yeast) is an oligotrophic, saprophytic and polymorphic yeast-like fungus naturally present in association with the endophyte populations in the phyllosphere and carposphere of various species of plants including both diseased and healthy grapevines [1,2]. The widespread occurrence of A. pullulans is attributed to its elevated tolerance to different ecological stresses and its high antagonistic activity against bacteria and fungi [1,9,10]. Because of these characteristics, A. pullulans has been exploited as a biocontrol agent for the management of Botrytis bunch rot (BBR) caused by the fungus Botrytis cinerea, and called grey mould, which is responsible for significant economic damage in vineyards and the postharvest decay of table grape [1,11,12]. Biological control represents a sustainable approach to produce high-quality grapes and wines with high standards of food safety without residues
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