Adaptability and Sensitivity of Trichoderma spp. Isolates to Environmental Factors and Fungicides

Biological control employs beneficial microorganisms to suppress phytopathogens and mitigate the incidence of associated plant diseases. This study investigated the in vitro development and survival of Trichoderma spp. isolates derived from commercial formulations under different temperatures, pH levels, and sodium chloride (NaCl) concentrations and with synthetic fungicides with distinct modes of action. Three isolates were analyzed: URM-5911 and TRA-0048 (T. asperellum) and TRL-0102 (T. longibrachiatum). The results revealed substantial variability among the isolates, with the optimal mycelial growth temperatures ranging from 24.56 to 29.42 °C. All the isolates exhibited broad tolerance to the tested pH (5-9) and salinity levels (250-1000 mM), with TRL-0102 demonstrating the highest salt resistance. The fungicide treatments negatively affected mycelial growth across all the isolates, with Azoxystrobin + Difenoconazole and Boscalid causing growth reductions of up to 50%. Notably, Boscalid enhanced conidial production more compared to the control (126.0% for URM-5911, 13.7% for TRA-0048, and 148.5% for TRL-0102) and decreased the percentage of inactive conidia to less than 10% in all the isolates. These results provide strategic information for the application of Trichoderma spp. in agricultural systems, supporting the selection of more adapted and suitable isolates for integrated disease management programs.