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Five samples of agricultural soil and five samples of Aloe barbadensis (P. Mill., 1768) plants with symptoms of wilt and root necrosis were collected in five localities of the state of Tamaulipas, México. The aims of this study were the morphological identification, molecular identification and in vitro evaluation of the antagonistic activity of Trichoderma spp. on Fusarium spp. Four strains of Trichoderma asperellum, one strain of Trichoderma harzianum and five strains of Fusarium oxysporum were identified by morphological and molecular methods. The evaluation of the antagonistic activity of T. harzianum isolate (TP) showed the highest inhibition in Fusarium spp. (78.80%). The evaluation of the antagonistic activity of Trichoderma spp. extracts in Fusarium spp. did not show significant differences between treatments (P ≤ 0.05), with Trichoderma growth percentages that oscillated between 81.08 and 94.38%. The native isolate of T. harzianum (TP) showed significant competitive capability against the mycelial growth of F. oxysporum. Trichoderma species are promising agents of biological control in the central area of the State Tamaulipas, Mexico. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the antagonistic effect in vitro of native strains of Trichoderma asperellum, Trichoderma harzianum and two isolates of Bacillus spp. against Fusarium oxysporum and Dickeya chrysanthemi. Bacillus, isolated from soil samples of Aloe vera plantations, was morphologically identified and a modified dual culture confrontation was carried out, placing the F. oxysporum in the center of the Petri dish and Bacillus in the four cardinal points; it was arranged under a completely randomized experimental design with five repetitions, the variables registered were percentage of antagonism, inhibition halo and concentration of conidia. For Trichoderma they were confronted against F. oxysporum and D. chrysanthemi with a dual confrontation, a percentage of inhibition and antagonism classification were determined. In the confrontation of T. asperellum it obtained a percentage of inhibition of 70.5% against F. oxysporum and 41.9% against D. chrysanthemi. Regarding the inhibition halos of Bacillus (B5 and B4), they obtained 4 mm. In the conidia concentration B5 showed 1.3, B4 2.6 and the control 12.6 spores per dilution. Trichoderma and Bacillus represent a viable alternative for the control of F. oxysporum and D. chrysanthemi. [ABSTRACT FROM AUTHOR]