Postharvest control of soft-rot fungi on grape berries by fungicidal treatment and Trichoderma

Abstract: The present research deals with the effect of postharvest treatment of grape berries with four commonly used fungicides and two forms of Trichoderma harzianum on the infection with soft-rot fungi- Rhizopus stolonifer and Mucor piriformis. This effect was evaluated by comparison of the external diameter of rot-lesion in treated and untreated berries, in addition to comparison of percent reduction in external rot-lesion diameter relative to control. Results indicated that the infection with R. stolonifer and M. piriformis was significantly reduced (P<0.05) in all treated berries in comparison with untreated control berries. The highest reduction in mean external rot-lesion diameter was obtained for both R. stolonifer and M. piriformis when inoculated berries were treated with Score? (difenoconazole) applied at 0.35%(v/v) or Switch? (cyprodinil + flodioxonil) applied at 0.20%(w/v) or formulated T. harzianum conidia in invert emulsion applied at 9.6x10⁸ conidia/ml of formulation (13.5, 13.2, and 19.3 mm, respectively for R. stolonifer; 7.2, 7.5, and 19.2mm, respectively for M. piriformis). The greatest decrease in percent reduction in external rot-lesion diameter relative to control was also obtained for both the fungal species when inoculated berries were treated with the same type of fungicides (Score? and Switch?) and Trichoderma (formulated T. harzianum in invert emulsion) (60.9, 61.7, and 44.1%, respectively for R. stolonifer; 74.5, 73.4, and 31.9%, respectively for M. piriformis). Overall results indicate that the most effective treatment obtained on grape berries could be integrated with other control measures being usually used in grape berry-rot management plans by alternating fungicidal treatment (e.g. Score? or Switch?) with application of formulated T. harzianum conidia in invert emulsion.