Comparison of electrostatic and conventional applications of Stratego to corn and soybean

by

Shawn P. Conley, Greg Shaner, David Eby

Contact: Dr. Shawn P. Conley    e-mail: spconley@wisc.edu

Summary:

Foliar fungicide usage has steadily increased over the last 5 years in Midwestern corn/soybean production systems.  In Indiana alone, 26% of all soybean growers used a foliar fungicide in 2006.  In 2007, fungicide label changes for corn, coupled with dramatically higher commodity prices, led to a considerable increase in the number of corn acres sprayed with foliar fungicides.  The objective of this experiment was to quantify the effect of aerial application volume on corn and soybean disease control and grain yield.  The experimental design was a randomized complete block design with 3 replications.  The volume treatments were 1) untreated control, 2) 5 GPA: Stratego at 10 fl oz/A + NIS 0.125% (v/v), 3) 2 GPA: Stratego at 10 fl oz/A + COC at 1 pint/A, 4) 1 GPA: Stratego at 10 fl oz/A (electrostatic).  The application timing for soybean and corn were R3 (first pod) and VT (tassel), respectively.  Plot size was ~6 A for both corn and soybean.  Disease severity was assessed on 20 plants in each plot. Rust was the predominant disease on corn, but gray leaf spot and northern corn leaf blight were also present.  No measurable disease pressure was noted in soybean.  In the corn experiment, disease severity means for the four treatments were: 1) untreated control: 6.95%, 2) 5 GPA: 3.68%, 3) 2 GPA: 3.97%, 4) Electrostatic (1 GPA): 3.31%.  These results suggest that fungicide efficacy was similar among the 5, 2, and 1 GPA aerial application rates. All treatments had less disease than the unsprayed corn.  Additional disease ratings and grain yield results will be presented at the NAAA meetings.

Manuscript not available online; please contact author for manuscript information.

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