Translocation and Fate of Dicamba in Purple Nutsedge

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Abstract
The translocation of 2-methoxy-3,6-dichlorobenzoic acid (dicamba-7-14C) in purple nutsedge (Cyperus rotundus L.) at different stages of development and under various light regimes was studied using autoradiography and liquid scintillation counting techniques. The fate of the herbicide was investigated by means of thin-layer chromatography. Dicamba was slowly but appreciably translocated in purple nutsedge following application to the leaves or roots. Foliarly applied dicamba movement proceeded both acropetally and basipetally, and the herbicide became widely distributed throughout the aerial parts of the plant and accumulated in the regions of meristematic activity. Dicamba was barely detectable in the underground organs, although it was excreted into the culture medium and passed through the rhizomes and tubers into daughter plants. Root-applied dicamba distribution was general throughout the plant except within the tubers and the tips of the leaves. Dicamba was barely detectable within the tubers, although it was present in quantity at or near the surface. Dicamba accumulation was evident at the tips of the leaves. Translocation was enhanced under low light conditions. Distribution of dicamba was profoundly affected by the stage of development of the plant. Greater translocation and broader distribution of the herbicide occurred in the vegetative stage of development. After flowering, movement out of the treated leaf decreased. Studies indicated that the herbicide was not degraded by the plant during the 10 days following treatment.