ABSTRACT
Weed infestation and control are primary concerns in crop production management. Growers focus on weed stress to their crops to minimize yield losses and reduce future infestations. The origin of weeds and crops is the same: wild progenitor species are selected by humans for their use as food, fiber, fuel, and drugs. Interactions between crops and weeds in agriculture occur throughout their life histories. Extensive genetic interaction between wild, weed, and cultivated phenotypes provides an extensive genetic reservoir metapopulation available to all inter-fertile species of the complex. Weeds react to crop stress by gradual evolution of phenotypic traits in aid of improved competitive ability, avoidance, synergy, and the introgression of new favorable traits drawn from the wild-crop–weed gene pool. Crops stress weeds by direct interactions, by human activity modulating the environment, by cropping practices exploiting weed life-cycle weaknesses, and by other sophisticated agricultural technologies.
