A synergistic agricultural formula including at least one diacyl or diaryl urea, such as a N,N′-diformylurea, and at least metal complex, such as metal complexes of cobalt, nickel, silver or other metals, is applied to plants at physiologically sensitive times resulting in prolonged and complete ethylene reduction. This synergistic agricultural formula gives those skilled in the art the ability to regulate important phenotypical parameters that lead to a variety of important agronomic and horticulture traits which improve crop yield parameters leading beyond that of its individual components.