In vitro evaluation of the inhibitory capacity of three Trichoderma isolates on Ralstonia solanacearum

Abstract

Bacterial wilt in bananas, caused by Ralstonia solanacearum or Moko, limits crop production and threatens Ecuador. This study evaluated Trichoderma isolates in laboratory conditions as an innovative alternative to ensure sustainability in banana production. The four R. solanacearum. isolates were obtained from banana plants exhibiting disease symptoms and were characterized through morphological and biochemical tests. Four treatments were evaluated: three isolates of fungi from the genus Trichoderma (Trichoderma viride, T. harzianum, T. asperellum) and one consisting of a combination of the three isolates above. The inhibitory capacity of the Trichoderma isolates on R. solanacearum colonies was measured. A completely randomized design with three replicates was used, and general linear and mixed models were employed, with qq-plot graphs for normality and residual plots for variance homogeneity. Furthermore, a Fisher's LSD test was conducted at a significance level of α = 0.05. In the biochemical tests, the bacterial isolates exhibited specific characteristics of R. solanacearum in two bacterial isolates. In the inhibition tests, treatment four and treatment one (consortium of the three Trichoderma isolates and Trichoderma viride) showed the highest inhibitory potential, with 76.07% and 61.19%, respectively. The consortium of Trichoderma isolates demonstrated the highest inhibitory potential against R. solanacearum, with day 10 being the time with the highest percentage of inhibition (72.61%). Keywords: Bacterial wilt, Ralstonia solanacearum, Trichoderma, inhibition