Role of essential oils in control of Rhizoctonia damping-off in tomato with bioactive Monarda herbage.

Plants in the genus Monarda produce complex essential oils that contain antifungal compounds. The objectives of this research were to identify selections of monarda that reduce Rhizoctonia damping-off of tomato, and to determine relationships between essential oil composition of 13 monarda herbages (dried and ground leaves) and disease suppression. Herbages were grouped into five chemotypes, based on essential oil composition and effective concentrations for reducing growth by 50% for Rhizoctonia solani.