Organizing Committee


Poster Presentations


Poster Presentations


Evaluation of fungicides and fungicide timing for the control of Phakopsora pachyrhizi in the United States

Presenter: T. A. Mueller

All authors and affiliations: T. A. MUELLER (1), C. A. Bradley (2), C. D. Chesrown (2), R. C. Kemerait (3), D. L. Wright (4), J. J. Marios (4), M. R. Miles (5), and G. L. Hartman (1,5). (1) Department of Crop Sciences, National Soybean Research Center, University of Illinois, Urbana, IL 61801; (2) Department of Plant Pathology, North Dakota State University, Fargo, ND 58105; (3) University of Georgia (Tifton Campus), Tifton, GA 31793; (4) University of Florida (North Florida Research and Education Center), Quincy, FL 32351; and (5) USDA-ARS, National Soybean Research Center, University of Illinois, Urbana, IL 61801

Timing of fungicide applications is a critical component in managing soybean rust and, if used effectively, may reduce the number of applications needed for economic benefit. The objectives of these experiments were to evaluate the effects of different timings of fungicide applications on soybean rust severity and yields. Trials were conducted in two locations with soybean rust (Quincy, FL, and Attapulgus, GA) and two locations without soybean rust (Urbana, IL, and Fargo, ND). Treatments in each field included applications with triazole (Folicur), strobilurin (Headline), or triazole-strobilurin combinations (Quilt or Headline + Folicur) at either (i) growth stage (GS) R1, (ii) GS R3, (iii) GS R5, (iv) GS R1 and R3, (v) GS R3 and R5, (vi) GS R1, R3, and R5, or (vii) not sprayed. The fungicides were applied with a backpack sprayer with TeeJet XR11002 tips at 40 psi. In locations with soybean rust, all treatments had significantly less disease severity. Preliminary analysis indicates that there were yield differences at least at some of the locations.

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