Epidemiological characteristics and phosphites in the management of Aspergillus niger rot on table grape

Abstract

The aim of this study was to evaluate the influence of epidemiological characteristics on the development of postharvest rot in table grape caused by Aspergillus niger Tiegh. and the effect of phosphite salts in vitro and in vivo. The inoculum concentration (102 to 107 conídios mL-1), wetness period (0, 12, 24, 36 and 48 h) and temperature (2, 5, 10, 15, 20 and 25 °C) of two A. niger isolates were evaluated. At postharvest management were used Ca, K, Cu, Mg e Zn phosphites at the concentrations 0.3; 0.9; 1.25; 1.7 and 2 g L-1 by dipping the grape clusters. After 12 and 24 h, the berries were wounded and inoculated with the fungus. The favorable conditions for the establishment of disease are high inoculum concentration (106 and 107 conídios mL-1), 48 h of wetness period and temperature about 25 °C. Phosphites shown to have a direct effect on the fungus by inhibiting the mycelial growth, especially zinc phosphite. There were no significant difference between phosphites for conidia germination. Just calcium phosphite is efficient in reducing disease severity, on the berries inoculated 12 hours after treatment. The treatments do not influence the chemical characteristics of grapes.