Ball moss is an epiphytic, perennial monocot that attaches to many surfaces, including ornamental plants. Though not parasitic, ball moss can reduce the growth and health of host plants. Controlling ball moss has thus become necessary. Recommended methods include spraying baking soda or copper fungicide. This study was designed to validate the recommended methods and discover new, efficacious botanical ingredients in laboratory and field experiments. The efficacy of baking soda, but not the copper fungicide, was confirmed. However, baking soda blindly damages host plants and is not environmentally friendly. A screening study over several candidates (a monocot herbicide, eugenol, thymol, oleander extracts) selected eugenol from clove essential oil. In repeated laboratory studies, eugenol formulated into a soluble liquid (ESL) at 1% concentration achieved comparable lethal levels to 50% baking soda solution against ball moss. Efficacy was most apparent when applied in autumn. In the field trials, spraying ESL directly onto ball moss on live oak trees rather than broadcasting from the ground was efficacious. Possible mechanisms and limitations were discussed.