Responses to Trichoderma Treatments Against Fusarium guttiforme Differ Between Two Pineapple Cultivars

Fusariosis, caused by Fusarium guttiforme, is a major disease of pineapple. This preliminary study evaluated the response to candidate Trichoderma spp. treatments in two pineapple cultivars contrasting in disease resistance. ‘BRS Imperial’ and ‘Pérola’ were evaluated in a randomized complete block design with three blocks and six treatments: a wounded control receiving distilled water, F. guttiforme alone, three Trichoderma isolates individually combined with the pathogen, and a mixture of the three isolates combined with the pathogen. The mixture contained equal volumes of the three isolate suspensions and a final total concentration of 1 × 107 conidia mL−1. Total affected internal stem area was measured 90 days after inoculation. A cultivar × treatment interaction was detected (F = 4.29; p = 0.0071). In ‘Pérola’, isolate 8C and the three-isolate mixture were associated with smaller total affected areas, with reductions of 45.95% and 52.59%, respectively, relative to the pathogen-only treatment; both contrasts remained significant after Holm adjustment. No planned contrast supported a reduction in ‘BRS Imperial’. The measured area included wound-associated alterations, and infection was not confirmed. Combined treatments received 10 mL, whereas the pathogen-only treatment received 5 mL; the observed differences therefore cannot be attributed solely to Trichoderma activity. Three plants per combination and one source of planting material per cultivar further limit precision and generalizability. These findings support further validation of the candidates under additional experimental and production conditions.