Essential oil nanoemulsions as a sustainable postharvest treatment to control anthracnose caused by Colletotrichum spp. in papaya and banana

Brazilian fruit production faces substantial postharvest losses due to anthracnose, creating demand for control strategies less dependent on synthetic fungicides. This study developed, characterized, and evaluated essential oil nanoemulsions of Cymbopogon flexuosus , Cymbopogon winterianus , and Zingiber officinale against Colletotrichum plurivorum and C. musae in papaya and banana. Formulations were prepared by low-energy emulsification and showed nanometric droplet sizes (95.9 to 171.3 nm) and low polydispersity indices (< 0.28); zeta potentials ranged from − 4.3 to -24.5 mV, consistent with steric stabilization typical of nonionic (polysorbate) systems. GC/MS identified geranial and neral in C. flexuosus , citronellal, geraniol and citronellol in C. winterianus , and ar-curcumene and α-zingiberene in Z . officinale as main constituents. In vitro, the C . winterianus and C . flexuosus nanoemulsions inhibited mycelial growth of both pathogens at low concentrations (0.03–0.07% essential oil). In fruit assays, the C. winterianus nanoemulsion reduced anthracnose severity in papaya in a concentration-dependent manner, with no visible lesion at 0.16% and no deterioration of the physicochemical parameters measured. Under the same conditions, the formulations did not reduce disease severity in banana, and the Z. officinale nanoemulsion showed low activity throughout. The C. winterianus nanoemulsion is therefore a potential candidate for postharvest control of papaya rather than a confirmed alternative to conventional fungicides, warranting further evaluation before broader application.