Tolerance and Residues of Hexazinone in Lowbush Blueberries

Applications of 1.5 and 3.0 kg/ha hexazinone in the spring of the sprout year in native lowbush blueberries (Vaccinium angustifolium Ait.) gave more effective selective weed control than fall treatments and increased crop stand and berry yields by about 30 and 50%, respectively. These treatments also gave excellent control of sheep-laurel (Kalmia angustifolia L.) and some herbaceous weeds. Applications in the spring of the fruiting year resulted in crop injury and reduced yields. Hexazinone and the metabolites A, B, D and E were not detected in any field-treated berry samples using an analytical technique that could detect below the established tolerance of 0.1 ppm.