ARS | Publication request: The Effects of Sprayer Configuration on Efficacy for the Control of Scab on Crabapple

Submitted to: Extension Circular
Publication Type: Experiment Station
Publication Acceptance Date: December 1, 2002
Publication Date: January 21, 2003
Repository URL: http://hdl.handle.net/10113/16699
Citation: Krause, C.R., Derksen, R.C., Horst, L., Zondag, R., Brazee, R.D., Klein, M.G., Reding, M.E. 2003. The Effects of Sprayer Configuration on Efficacy for the Control of Scab on Crabapple. Extension Circular. 189:65-68

Technical Abstract: Direct evaluation and correlation of fungicide coverage, and the amount of apple scab disease were investigated relative to the effects of sprayer/nozzle. Dedicated nursery plots consisted of 6 crabapple treatment rows with 4 replications each. Crabapple whips of each cultivar, Malus spp. cv. `Candied Apple' and cv. `Red Jade' were used with barrier rows. Treatments consisted of: an axial flow, airblast sprayer with conventional-high volume nozzle delivering 300 psi; an axial flow, airblast sprayer applied treatments of mankocide fungicide spray with air induction nozzles delivering 120 psi; an experimental air curtain sprayer or cross-flow fan sprayer with air induction nozzles delivering 120 psi; and an unsprayed control. Leaf analysis was performed using a cold field emission scanning electron microscope and a variable pressure scanning electron microscope, both equipped with energy dispersive x-ray analyzers to directly visualize and identify the pathogens and morphologically and chemically characterize any fungicide present. Disease evaluation was made using a Horsfall-Barrett Scale read each month during spray treatments. A portable meteorological station monitored weather conditions within the experimental plot. Fungicide coverage was measured with EBA, but low disease pressure did not permit quantifying differences in efficacy.