Influence of Spray Volume on Spray Deposition and Coverage within Nursery Trees

Information on better utilizing airblast sprayers to achieve high pesticide spray application efficiency in nursery tree production is needed. Foliar spray deposition and coverage at different heights inside crabapple tree canopies were investigated for a conventional airblast sprayer operating at four different application rates ranging from 230 to 900 L/ha [24 to 94 gallons per acre (GPA)]. Deposition on the ground at various distances from the sprayer was also measured at the 700 L/ha (73 GPA) application rate. Foliar deposition and coverage on targets below 2.6 m (8.5 ft) inside tree canopies increased as the application rate increased, but the increase in the coverage was much lower than the deposition. For trees taller than 2.6 m (8.5 ft), the sprayer could not deliver uniform spray deposition and coverage across the tree height. The portion of trees below 1 Received for publication February 15, 2007; in revised form September 2, 2007. Mention of proprietary product or company is included for the reader’s convenience and does not imply any endorsement or preferential treatment by either USDA-ARS or The Ohio State University. The authors greatly acknowledge technical assistance by B.A. Anderson, A. Clark, A.A. Doklovic, M.S. Giovannini, L.E. Horst, L.A. Morris, B.E. Nudd, D.T. Troyer, K.A. Williams in preparing setup and collection of large quantity of samples in the field. Cooperation in providing operating facilities, equipment, and experimental field space by R. S. Lyons, owner and R.A. Hart, R.G. Headley and J.F. Daley, Sunleaf Nursery, Madison OH is also gratefully acknowledged. 2 Agricultural Engineers, Research Entomologist, and Research Plant Pathologist, respectively. USDA/ARS, ATRU, Wooster, OH 44691. Email: [email protected]. 3 Extension Horticulturist, The Ohio State University Extension, Lake County, OH 44077.