Fungos associados a sementes de melão e o antagonismo de isolados de Trichoderma sp. contra isolados dos complexos de espécies Fusarium incarnatum-equiseti e Fusarium solani

Abstract

The melon (Cucumis melo L.) is botanically classified as a vegetable, although it is marketed as a fruit, and has great economic importance. It is low in calories, high in fiber, and composed of 83% water. For many years, the Northeast region from Brazil has led national production, especially the states of Rio Grande do Norte, followed by Ceará, Bahia, and Pernambuco. The cost of production is directly correlated with the lack of adequate management practices, especially those related to disease control. Among fungal problems in the field, Fusarium is one of the main groups responsible for losses in melon crops, causing fruit rot and wilt. An alternative method for seed treatment that stands out is the biological control with the fungus Trichoderma, which is a naturally occurring saprophytic soil organism capable of exerting antagonistic activity against several phytopathogens. The present study aimed to identify the association between fungi and seeds from different melon fruits and to analyse the potential antagonistic effect of different Trichoderma isolates against the detected Fusarium species. Seeds of Amarelo, Cantaloupe, Dilo, and Pele de Sapo varieties, with and without surface disinfestation, were analyzed using the blotter test method. The fungi identified were Aspergillus spp., Penicillium spp., and Fusarium spp., the latter being identified in the seeds of the Amarelo and Dilo varieties. Morphological characteristics allowed for the identification of the Fusarium solani species complex (FSSC) and the Fusarium incarnatum– equiseti species complex (FIESC). The in vitro antagonism assay showed that Trichoderma spp. isolates were effective in inhibiting the mycelial growth of the pathogens, especially with the FVE23 isolate, representing the highest antagonic potential, mainly against the FSSC. The results indicate that melon seeds can be important vehicles for the dissemination of diseases of Fusarium, and the biological control with Trichoderma spp. represents an alternative option and a sustainable management strategy for disease control in the melon cultivation.