2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Herman Losely & Sons, Inc. Additional details of research can be found in the report for the parent CRIS 3607-21620-006-00D Biological, Microclimate, and Transport Processes Affecting Pest Control Application Technology. Due to the large number of species in nursery production, commercially available sprayers have limited capacity for treating specific nursery species. To control insects and diseases inside dense nursery canopies, existing spray techniques have used either excessive or inadequate pesticide delivery to target areas, resulting in increased cost and contamination of the environment. Growers are seeking new sprayers or customized delivery systems that can operate economically and effectively with minimum canopy damage and optimum pest control. A specially designed five-port, air-assist sprayer was modified and investigated to improve spray penetration and coverage in dense nursery crops. The air assist sprayer with the improved five-port nozzles could bring sufficient amount of spray inside dense nursery canopies with reduced spray application rates. Information from this study will help customize the sprayer operation conditions to accurately deliver sufficient pesticide to the inner or lower nursery canopies where insects frequently attack, resulting in significant cost reduction.