This chapter discusses endophytic classification, recognition of endophytic status in planta, complete process of plant colonization by endophytic bacteria, multifaceted benefits of endophytic bacteria, and endophytes as parasites.

This chapter discusses Trichoderma biodiversity and potent isolate identification for applying as a biological control agent. The main modes of action of Trichoderma spp. are described, i.e. mycoparasitism of fungal pathogens with subsequent release of cell-wall-degrading enzymes such as cellulases, glucanases, chitinases, etc., and antibiosis by secretion of antimicrobial secondary metabolites and competition for nutrients. The application of Trichoderma spp. as biofertilizers is also discussed. Commercial formulations of Trichoderma spp. are described, and future prospects are mentioned.