Measurement of herbicide spray deposits on foliage by fluorescence I. Paraquat deposits on Vicia faba

An investigation revealed a paraquat-compatible fluorochrome that fluoresces at 600 nm where the herbicide fluorescence is negligible. Acceptable amounts of this fluorochrome are recoverable from dry spray deposits of paraquat + fluorochrome mixture sprayed on various broad-leaf weeds and bean leaves but care must be taken if a wetting agent is used for extraction purposes because the fluorescent intensity of the fluorochrome is affected by wetting agents. A procedure is given for extracting and measuring the fluorochrome from spray deposits on foliage.