VOLUME, SPEED, AND DISTRIBUTION TECHNIQUE EFFECTS ON POINSETTIA FOLIAR DEPOSITS

The influence of spray volume, application speed, and distribution tec hnique on spray deposits found on greenhouse poinsettias was investiga ted Foliar spray deposits were measured on upperside and underside lea f surfaces in the top and bottom canopy locations. Five different appl ication techniques were used to treat 12-week-old, bench-grown, greenh ouse poinsettias. High-volume, high-pressure techniques were used to s imulate variations on conventional application practices. Air-assisted , electrostatically charged sprays were used to simulate low volume, h and-directed, application techniques. A mechanical aerosol generator w as used to simulate low volume applications generated at a single poin t and intended to fill the greenhouse with a fog. Spray deposition was measured by spectral analysis of food dye tracer. Spray deposits were higher in the top canopy location and on the upperside leaf surfaces. The lowest spray deposits were found in the bottom canopy location an d on the undersides of those leaves, Hand-directed distribution techni ques resulted in significantly higher spray deposits compared to the w hole-room fogging spray distribution technique. Slower applications th at doubled the total application time and that were made using the sam e spray volume as higher speed applications nearly doubled underside l eaf deposits. The greatest variability in spray deposits was found wit h higher application speeds and reduced volume applications made throu gh the high pressure handgun. It was observed that the higher spray vo lumes increased spray deposits through redistribution resulting front run-off and touching leaf surfaces.