*2.6. Trichoderma–Trichoderma Interactions through Co-Culture*

In our study, co-culture was carried out to evaluate the ability of selected *Trichoderma* spp. cultures to produce secondary metabolites. This was carried out on solid culture medium potato dextrose agar (PDA) for three selected fungi: *T. harzianum* (PGT4), *T. reesei* (PGT5) and *T. reesei* (PGT13) based on its antibacterial activity against *Xanthomonas oryzae* pv. *oryzae*. These fungi were cultured on PDA and incubated at 25 ◦C for 7 days. After incubation, 10 mm of fungal discs were taken from actively growing margins of *Trichoderma* spp. on PDA plates. Two different *Trichoderma* spp. cultures of 10 mm were placed on PDA plates at the opposite ends of the petri plates, making a total of 3 dual cultures (pairwise combinations). Triplicates of both dual and monocultures were made and incubated under dark conditions for 9 days at 25 ◦C [41].
