Pre-selection in laboratory tests of survival and competition before field screening of antagonistic bacterial strains against Botrytis bunch rot of grapes

Publication date: September 2018Source: Biological Control, Volume 124Author(s): Carlos Calvo-Garrido, Rana Haidar, Jean Roudet, Thomas Gautier, Marc FermaudAbstractWith only a few biocontrol products currently registered against Botrytis bunch rot (BBR) of grapes, there is a crucial need for new antagonistic strains that are able to survive and efficiently suppress B. cinerea under vineyard conditions. The aim of this study was to establish and follow a pre-selection process among potential antagonistic bacterial strains, previously identified in vivo for efficacy, and to carry out a further field screening assay using a reduced strain number. Ten bacterial strains were pre-selected and tested, in vitro and in vivo, to characterise their mode of action and population dynamics under simulated climatic regimes. Four candidate strains were then selected and characterised for high efficacy in vivo, known mode of action and marked survival ability. Some suitable additives for increasing strain adherence on grape berry surface were tested prior to field applications, indicating one commercial adjuvant for potential improved bacterial persistence in the field. The four strains were applied separately in an experimental Merlot vineyard near Bordeaux (SW France), either at five key phenological stages, or following a specially developed Disease Risk Index (DRI). The Bacillus ginsengihumi S38 strain treatments significantly reduced BBR incidence by 72–75% compared to the control, wh...
Source: Biological Control - Category: Biology Source Type: research