Antagonistic activity of biocontrol agent Trichoderma spp. against Fusarium sp., the causal agent of Ananas comosus fruitlet rot

Abstract

Pineapple (Ananas comosus) is a significant crop, with an annual production exceeding 25 million tons. However, fusariosis can severely impact its cultivation, a fungal disease that causes fruitlet rot and results in substantial yield losses. To decrease dependency on chemical control methods, biocontrol agents (BCAs) present a promising alternative. Among these, Trichoderma species are noteworthy due to their diverse antagonistic mechanisms. The efficacy of each mechanism can be assessed through fungal confrontation assays. This study aimed to isolate, identify, and evaluate in-vitro nine Trichoderma spp. strains as potential BCAs against Fusarium sp. associated with pineapple fruitlet rot. The antagonistic fungi were isolated from rhizosphere soils in both open-field and greenhouse pineapple farms in Misiones province, Argentina. Identification of the fungi required both morphologic and genetic data. In the in-vitro assays, the capabilities for direct competition for substratum, production of metabolites, and mycoparasitism were evaluated. The results indicated that isolates T. harzianum TC7, T. harzianum TC9, T. asperellum TU3, and T. asperellum TU4 had statistically superior inhibitory effects against Fusarium sp. These isolates can be potentially used in formulating natural fungicides to reduce pineapple fruitlet rot caused by Fusarium, promoting sustainable production practices. Keywords: pineapple, confrontation, mycoparasitism, metabolites, ITS region