The nematicidal properties of Trichoderma species have potential for developing safer biocontrol agents. In the present study, 13 native Trichoderma strains from T. citrinoviride, T. ghanense (2 strains), T. harzianum (4), T. koningiopsis, T. simmonsii, and T. virens (4) with nematicidal activity were selected and cultured in potato dextrose broth to obtain a culture filtrate (CF) for each. Each CF was partitioned with ethyl acetate to obtain organic (EA) and residual filtrate (RF) fractions, which were then tested on second-stage juveniles (J2s) of the nematodes Meloidogyne javanica and M. incognita in a microdilution assay. The most lethal strains were T. harzianum Th43-14, T. koningiopsis Th41-11, T. ghanense Th02-04, and T. virens Th32-09, which caused 51–100% mortality (%M) of J2s of both nematodes, mainly due to their RF fractions. Liquid chromatography–diode array detector-electrospray-high resolution mass spectrometry analysis of the most-active fractions revealed sesquiterpene and polyketide-like metabolites produced by the four active strains. These native Trichoderma strains have a high potential to develop safer natural products for the biocontrol of Meloidogyne species.

Plant extracts are a valuable alternative to control pathogens of horticultural crops. In the present study, four species of pathogenic fungi were isolated from leaf spots on Solanum lycopersicum and identified by traditional and molecular techniques as Alternaria alternata ITC24, Corynespora cassiicola ITC23, Curvularia lunata ITC22, and Fusarium equiseti ITC32. When 11 aqueous extracts from eight native plants of the Yucatan Peninsula were tested against the four fungi in vitro, the extract from Croton chichenensis roots was most active, inhibiting mycelial growth (79–100%), sporulation (100%), and conidial germination (71–100%) at 3% (w/v). A logarithmic–diagrammatic scale of the pathosystem C. cassiicola–S. lycopersicum was established and used to assess disease severity on inoculated tomato plants in a greenhouse after treatment with the aqueous extract from C. chichenensis roots at 12% (w/v). After 21 days, the disease severity was 57% lower than on the control without extract applied. This dose of the extract was not phytotoxic to tomato leaves and was compatible with the beneficial organisms Bacillus subtilis CBCK47 and Trichodema asperellum Ta13-17. The antifungal efficacy of C. chichenensis is highly promising for incorporation into integrated disease management of tomato crops.

El presente estudio se dirigió al aislamiento e identificación de especies de Trichoderma y su estimación de promoción de crecimiento vegetal en plántulas de Solanum lycopersicum L. cv. Río Grande. Se aislaron cuatro cepas; dos se identificaron como T. ghanense (Th26-52 y Th02-04), una como T. citrinoviride (Th33-58) y otra como T. harzianum (Th33-59). Los resultados de promoción en plántulas de S. lycopersicum en concentraciones de 106 conidios·ml-1 más fertilización química a 50%, mostraron diferencias estadísticas significativas entre tratamientos (p ≤ .01). Los tratamientos con Trichoderma spp. incrementaron de 24.28 a 38.53% la altura de plántula, de 2.29 a 14.09% el diámetro de tallo, de 8.48 a 16.54% la longitud de raíz, de 0.37 a 2.68% el volumen radical y de 0 a 23.07% la biomasa seca total...