Efficacy of Putative Spondias Leaf Extracts Against Macrophomina spp. in Melon Plants

Abstract

Fungi of the genus Macrophomina are widely distributed necrotrophic pathogens associated with various agricultural crops, including charcoal rot of melon. The limited effectiveness of chemical and genetic control strategies, combined with the high survival of the pathogen in soil and the absence of resistant cultivars, highlights the need for more sustainable management strategies. In this context, this study aimed to evaluate the antifungal potential of leaf extracts from Spondias species against Macrophomina phaseolina, Macrophomina pseudophaseolina and Macrophomina euphorbiicola, under in vitro and in vivo in melon plants. Ethanolic extracts (70%) were obtained from leaves of five Spondias genotypes (UMBU, CAJ-52, CAJ-53, SERI-60 and SERI-64). The in vitro assay was conducted using the disk diffusion method, at concentrations of 0%–50%, evaluating the percentage of mycelial growth inhibition (MGI) and determining the effective concentration (EC₅₀). In vivo assays were performed in a greenhouse using ‘Natal’ RZ F1 melon seeds grown in infested soil, with weekly applications of the extracts (15%). Forty days after sowing, disease incidence and severity, as well as biometric variables, were evaluated. The in vitro results showed that all extracts caused 100% inhibition of mycelial growth at a concentration of 15%. Under in vivo conditions, CAJ-53, CAJ-52 and SERI-64 extracts showed greater efficiency in controlling M. phaseolina, M. pseudophaseolina and M. euphorbiicola, with severity reductions of 53%, 65% and 64%, respectively, compared to the positive control. Overall, leaf extracts of Spondias spp. inhibited the growth of Macrophomina spp. and reduced disease severity, highlighting their potential as a sustainable control alternative.