Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4 (1H, 3H)-dione] effectively controlled herbaceous weeds in a loblolly pine (Pinus taeda L.) plantation in 1975. Pine seedling height increased as a result of weed control following 1 to 3 kg/ha applications but phytotoxic symptoms were evident. A 1976 field study indicated activated charcoal root coatings may reduce phytotoxic action. Hexazinone at 3 and 4 kg/ha applied to either the foliage or the soil was toxic to potted pine seedlings in 1976. The addition of surfactant to hexazinone treatments at 2, 3, and 4 kg/ha increased pine phytotoxicity to unacceptable levels. When hexazinone was applied to soil at 2, 3, and 4 kg/ha, activated charcoal root coatings reduced pine mortality to acceptable levels on Norfolk sandy loam. Charcoal was less effective on Madison clay loam. Pine tolerance on both soils was acceptable at 2 kg/ha.
