Native and Non-Native Soil and Endophytic Trichoderma spp. from Semi-Arid Sisal Fields of Brazil Are Potential Biocontrol Agents for Sisal Bole Rot Disease

Sisal (<i>Agave sisalana</i>) bole rot caused by <i>Aspergillus welwitschiae</i> is the main phytosanitary problem affecting sisal in the Brazilian semi-arid region. The aim of this study was to evaluate <i>Trichoderma</i> spp. as biocontrol agents for sisal bole rot. Native and non-native species, both soil inhabitants and endophytes, and isolated from different plant hosts were tested. Anatomical studies of the interaction among <i>A. sisalana</i>, <i>Trichoderma</i> spp., and <i>A. welwitschiae</i> were performed. <i>T.</i> cf. <i>asperellum</i> (isolate F12), an endophyte of sisal leaves; <i>T.</i> cf. <i>asperellum</i> (TCS83) from banana plant soil; <i>T. lentiforme</i> (TCS15) and <i>T. harzianum</i> (species complex) (TCS35 and TCS76) from sisal root soil; <i>T. spirale</i> (R62) and <i>T. saturnisporum</i> (R75), endophytes of sisal roots, were the most efficient isolates, with inhibition of <i>A. welwitschiae</i> mycelial growth by up to 70%, and inhibition of sporulation and spore germination by 99%. A reduction in disease incidence of 70 to 93% and in disease severity of 97% was achieved. <i>T. lentiforme</i> (TCS1), <i>T. harzianum</i> (species complex) (TCS35 and R72), and <i>T. koningiopsis</i> (R78) showed mycoparasitism. An increase in cell wall thickness of bole tissue colonized by these <i>Trichoderma</i> species indicated that induced plant defense responses occurred, preventing pathogen colonization, which should be further investigated. Native and non-native <i>Trichoderma</i> species can control sisal bole rot disease.