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Poster Presentations


Poster Presentations

Response of soybean to timing of fungicide applications in the presence and absence of Phakopsora pachyrhizi

Presenter: T. A. Mueller, University of Illinois-Dept. of Crop Sciences, Urbana, IL
Coauthor(s): C.A. Bradley-North Dakota State University, Fargo, ND; C.D. Chesrown-North Dakota State University, Fargo, ND; E.R. Walker-USDA-ARS, MSA, CG & PRU, Jackson, TN; C.H. Koger-USDA-ARS, Stoneville, MS, W. Morel-Centro Regional de Investigatión Agrícola, Dirección de Investigación Agrícola, Ministero de Agricultura y Ganadera, Capitán Miranda, Itapa Paraguay; M.R. Miles-USDA-ARS,University of Illinois, Urbana, IL ; and G.L. Hartman-USDA-ARS and Dept of Crop Sciences, University of Illinois,Urbana, IL

Timing of fungicide applications may be critical in managing soybean rust and may, if used effectively, reduce the number of applications needed for economic benefit. The objectives of these experiments were to evaluate the affects of different timings of fungicide applications on soybean rust severity and yields. Trials were conducted in Paraguay (three locations) and in the U. S. (four locations). In Paraguay, all three locations were infected with soybean rust; in two locations rust significantly impacted yield. Trials in the U.S. were located in Illinois, Mississippi, North Dakota, and Tennessee; none were infected with soybean rust. A representative soybean cultivar was planted in each region for this experiment. Treatments in each field included applications with: triazole (Folicur), strobilurin (Headline), or a triazole-strobilurin combination (Quilt) at either (i) growth stage (GS) R1, (ii) GSR3, (iii) GS R5, (iv) GS R1 and R3, (v) GS R3 and R5, or (vi) not sprayed. The fungicides were applied with a backpack sprayer with TeeJet XR11002 tips at 40 PSI. In Paraguay two locations yield was significantly greater than the control for all treatments. In one location in the U.S., all but one treatment had significantly greater yield than the control, and in two other locations, there was no statistical difference between the control and most treatments. Yield data from these trials will be compared after data analysis.

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