Deposition and Efficacy of Electrostatic Versus Conventional Fungicide Spray Systems

 

By

 

Shawn Conley

 

Contact: Shawn Conley   email:  conleysp@purdue.edu

 

Summary:

The potential threat of Asian soybean rust coupled with frequent infestations of soybean aphid has raised concerns from growers regarding the capability of custom applicators to make timely treatments against these soybean pests.  We conducted three separate experiments to compare the deposition and efficacy of electrostatic versus conventional aerial fungicide applications.  In experiment 1 we compared the percent canopy covered by spray droplets from ground application at 15 GPA, aerial application at 5 or 2 GPA utilizing conventional flat fan tips, and aerial application at 1 GPA utilizing electrostatic spray technology.  Dye was added to the spray solution and applied to soybean at the R2 stage of growth.  After the spray solution was allowed to dry, soybean plants were collected from each treatment.  Trifoliates from these plants were removed, tagged, and digitally photographed under black light, which revealed spray coverage area. Spray canopy coverage was quantified with ASSESS digital analysis software.  In experiment 2 we compared the efficacy of Quadris fungicide applied with conventional flat fan tips at 5 GPA versus the electrostatic spray system in production seed corn fields.  In experiment 3 we quantified the impact of fungicide and application technology on yield of field corn and soybean.  In experiment 1 the ground application gave the greatest overall plant coverage (7.3%).  No differences existed among the 5, 2, and 1 GPA aerial application rates, (1.4% overall plant coverage).  In experiment 2 disease control was similar between the conventional  and the electrostatic spray system.  Yield results will be presented for experiment 3 at the NAAA meetings.  Our preliminary results suggest that deposition and fungicide efficacy were similar among the 5, 2, and 1 GPA aerial application rates. 

 

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