Mastiff PGR is a plant growth regulator (PGR) which produces desirable growth reduction in a wide variety of ornamental trees. With a single application, vegetative growth generally is reduced up to 70% over a three-year period. Results will vary depending upon tree species and local growing conditions. For use by professional arborists/applicators, grounds maintenance professionals, city foresters, electric utility foresters/contractors, and landscapers when trees are planted too close together, too close to homes or decks, along scenic lines of sight, near utility and power lines, along sidewalks or in vaults or placed in containers or tree wells. For more information, click here.