This experiment was established on mature navel orange trees in a randomized complete block design using double tree plots and five replications. Two flower clusters with 10-20 blossoms at the pinhead stage were selected per tree and flagged for future reference. KeyPlex 350 OR was applied at 3 quarts per 125 gallons of spray on March 3 and again on March 8, 2008. Application was made using a single nozzle handgun at 100 psi with the entire canopy sprayed to runoff. Topsin M WSB at 2 pounds per 125 gallons was also applied on March 8, 2008, as a grower standard. Trees were also maintained as an untreated check.