Papaya is one of the most cultivated fruit in tropical and subtropical countries.
It is affected by several postharvest pathogens, including Colletotrichum gloeosporioides.
The main goal of this research was to evaluate the antagonistic capacity of five strains of Trichoderma against C. gloeosporioides using in vitro and in vivo tests.
All strains of Trichoderma inhibited radial growth on a plate of Colletotrichum by 50–60%. Moreover, Trichoderma longibrachiatum showed the highest colonization (87.45%) on Colletotrichum.
In tests to determine the mechanism of action, mycoparasitism was observed.
Trichoderma harzianum was mainly found invading mycelium of C. gloeosporioides. The severity measure showed that it was the interaction of the strain with the different time of inoculation that influenced the size of the lesion, with the largest decrease in lesion size occurring when Trichoderma viride was inoculated 24 h before the pathogen.
On the other hand, the Trichoderma strains did not cause color changes on papaya fruits.