Monterey 8 oz. Mark-It-Blue Spray Solution. This concentrated blue colorant provides temporary highly-visible evidence of spray application patterns, eliminating skips and overlapping. It readily dissipates, is non-toxic, and totally compatible with water-soluble solutions. Ideal for golf courses, parks, cemeteries, athletic fields, and any turf or grass areas, Mark-It Blue washes off without staining vegetation or soil and can be used with all types of equipment.