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Poster Presentations


Poster Presentations


Yield and economic analysis of pyraclostrobin application to soybean in the presence and absence of foliar diseases

Presenter: Travis C. Gustafson

Other authors and affiliations: Loren J. Giesler. University of Nebraska, Plant Pathology, Lincoln, NE 68583, U.S.A.

Strobilurin fungicides have been shown to increase crop yields through suppression of foliar diseases and demonstrated to increase yield in the absence of disease in some cases. From 2005 to 2007, trials were conducted at four locations in eastern and central Nebraska to determine the effect of pyraclostrobin application on soybean yield. Applications (6 fl oz. of Headline/acre) were made at the R3 growth stage. Brown spot (Septoria glycines) was the main foliar disease present and severity was assessed 23 weeks after fungicide application. The analysis includes sites where there was no disease (severity <10%) to determine if there was a yield and/or economic response to a fungicide application. Twenty-three out of 52 comparisons (44%) indicated positive economic returns from pyraclostrobin application. Economic returns were based on $8/bu soybean market price and $18/acre product and application costs. When all sites, years, and varieties were combined, trials with brown spot (>10% severity and less than 30% severity in all trials) had an average of 1.8 bu/acre (P = 0.05) yield increase with the application of pyraclostrobin. Sites without brown spot had a 1.4 bu/acre (P = 0.04) increase in yield. There were no variety by treatment interactions. Because of a potential yield increase associated with pyraclostrobin application, these results suggest the need to consider variety sensitivity to brown spot when deciding to apply pyraclostrobin, even under low disease pressure.

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