Applying antagonist yeast strains to control mango decay caused by Lasiodiplodia theobromae and Neofusicoccum parvum

Abstract

Successfully inserting a biocontrol agent (BCA) in the integrated management of mango fruit decay can be affected by several factors, including BCA inoculum density and the timing of its application. This study focused on improving biocontrol efficacy by adjusting doses of a BCA formulation and the timing for the substitution of synthetic fungicides sprays. Technical grade formulations containing increasing doses (104 – 108) of the yeast strains Saccharomyces sp. ESA45, S. boulardii ESA46, Saccharomyces sp. ESA47, and Pichia kudriavzeviii CMIAT171 were applied to mango fruits, followed by the inoculation of Lasiodiplodia theobromae and Neofusicoccum parvum in artificial wounds. Non-linear regression analysis of increasing doses of the BCAs against severity data and curve slopes comparison showed a significant difference in control efficiency among yeast strains. A log-linear regression model showed that ESA45 and CMIAT171 exhibited lower doses to achieve 90% control. Two field experiments were conducted in commercial mango orchards cultivated with the cultivars ‘Kent’ and ‘Palmer’. Starting the substitution of fungicides by BCA in fruit onset and when fruits achieved egg size resulted in lower fruit rot incidence and severity during cold storage and shelf life. The complete substitution of fungicides during fruit development did not show consistent performance. Similarly, applying BCA formulation only at the end of fruit development did not hinder the establishment of quiescent infections.