Aerial Methods for Increasing Spray Deposits on Wheat Heads

Abstract

Development and evaluation of aerial application technologies to enhance the efficacy offungicides and biological control agents with standard aerial spray rates is a priority research area ofthe U.S. Wheat and Barley Scab Initiative. Consequently, the ARS Aerial Application Technologyresearch team at College Station, Texas, initiated research to assess aerial spray technologies thatcould lead to increased spray deposits on wheat heads for Fusarium head blight suppression. Thegoals of the effort were to: 1) Identify the capability of conventional aerial application practice todeposit sprays on wheat heads and determine the properties of those spray deposits; 2) Determine ifthe amount of spray deposits on wheat heads can be enhanced through the use of very fine spraysproduced by rotary atomizers, and characterize those spray deposits; and 3) Determine if aerialsprays applied from two directions would increase deposits on wheat heads, and characterize those spray deposits. Three large- acreage aerial spray studies were conducted to achieve these projectgoals. Treatments were applied in randomized blocks with three replications. Multiple sub-samplesof wheat heads and artificial collectors were collected and analyzed to characterize spray depositsfrom the specified treatments. Fluorometry and image analyses were used to quantitate andcharacterize spray deposits on wheat heads and artificial collectors. Fine droplet spectrum spraysapplied with rotary atomizers gave the greatest spray deposits on both wheat heads and artificialsamplers. Medium droplet spectrum sprays gave the least deposits on wheat heads regardless ofspray rates between 19 and 94 L/ha (2 and 10 gal/acre). Results from these studies on optimizingaerial spray deposits will be implemented in disease control studies to provide guidance for aerialfungicide applications for suppression of Fusarium head blight.