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Effect of biological agents (strains-PUCV-VBL) on summer bunch rot of table grapes cv. Thompson seedless in Chile

Fabiola Cádiz: Pontificia Universidad Católica de Valparaíso

<div>Summer bunch rot (SBR) caused by fungal complex including <em>Botrytis cinerea</em>, <em>Penicillium expansum</em>, <em>Aspergillus niger</em> and <em>Rhizopus stolonifer</em>, is an important disease of tables grapes. We have developed a product with two biological agents (BA), <em>Gluconobacter cerinus</em> and <em>Hanseniaspora hosmophila</em> for SBR control. Successful results were obtained testing BA as biofungicide on SBR in Red Globe (RG) cv. both in vivo and field trials. BA has not been tested in Thompson Seedless (TS) cv. and the literature indicates that the genus <em>Gluconobacter</em> would be one of the causative agents of sour rot in TS. The objective of this study was to evaluate the BA on control of SBR in TS. For this purpose, TS grapes (n = 5) were inoculated using the BA mixture in two concentrations. After 24 h, the grapes were inoculated using conidia of SBR causative agents. Non-inoculated and inoculated grapes were left as negative and positive controls. In a second trial in the same way, but using the BA mixture in a new formulation, bunch of grapes cv. TS (n = 3) were sprayed. The results of the first trial indicate that the mixture of BA in low and high concentrations could inhibit the development of SBR, but producing a browning of the berries. However, in the second trial, when a new formulation of the BA mixture was used in the group, summer cluster rot was controlled, and browning was not observed in the berries. Sour rot was not observed in either of the two trials.</div>