Herbicide synergy occurs when a combination of two or more herbicides works better, or the effect is more prolonged than the sum of the effects of the individual ingredients independently. Herbicide tank- mixing has often been preferred over sequential applications because they require less time, cost less than applying each herbicide individually, and usually increase the spectrum of weed control. In citrus, studies demonstrate improved weed management, when herbicides are applied in combinations. This article provides some insights into the factors that influence the efficacy and interaction of herbicide mixtures in target weeds.