Mark-it Blue is a concentrated blue colorant designed to provide temporary highly-visible evidence of spray application patterns. Mark-it Blue readily dissipates, is non-toxic and totally compatible with water-soluble solutions. It is ideal for golf courses, parks, cemeteries, athletic fields and any turf or grass areas - virtually anywhere where spray evidence is needed. Use Mark-It Blue to keep track of where you have already sprayed fertilizer or pesticide so you don't re-spray the same places wasting time and material in the process. Compatible with all types of sprayers and equipment, will not permanently stain equipment, vegetation, or soil.