Antimicrobial, phytotoxic, and insecticidal activity of 30 fungal isolates obtained from leaves of weeds and wild herbaceous plants was assessed. Antibacterial, antifungal, phytotoxic, and insecticidal activity was found in over 50%, 40, 47, and 40% of the isolates, respectively. These findings may be important for toxicological assessment of potential mycoherbicides, and may also provide a basis for investigation of the patterns of development of phyllosphere communities affected by fungal metabolites.