An environmentally compatible, selective herbicidal composition is provided that includes an activator adjuvant for enhancing the efficacy of the composition. While the activator adjuvant can be used in combination with a variety of herbicides, in an exemplary embodiment the herbicidal composition includes a metal chelate that is formed from a transition metal component and at least one chelating agent. The activator adjuvant can enhance, even synergistically effect the efficacy of the composition, while maintaining the selectivity of the herbicide.