Tolerant species metabolize hexazinone faster than sensitive species.
For conifers, at least part of the selectivity is due to the tree roots being deeper than hexazinone leaches into the soil. For broadcast applications, apply preemergence or as a postemergence foliar spray during active plant growth. Apply Pronone with an approved granular applicator. Unique Characteristics Rainfall is needed to activate hexazinone in the soil. Do not use on sandy, gravelly or rocky soils, or on frozen ground.