Sunday, 5 February 2006

This presentation is part of: Crops Posters

Large Plot Evaluation of Soybean Rust Control.

Philip Jost, Robert C. Kemerait Jr., Layla Sconyers, and James Clark. University of Georgia, PO Box 8112 GSU, Statesboro, GA 30460

A large plot trial was established in Appling County, Georgia to evaluate fungicides for the control of soybean rust. Treatments consisted of 7.8 oz/A Headline SBR, or 15 oz/A Quilt applied at the R2 and R4 growth stage 7.8 oz/A Headline SBR at R2 followed by 4 oz/A Folicur at R4, 7.8 oz Headline SBR at R2 only, and 7.8 oz/A Headline SBR applied at R5. The R2, R4, R5 applications were made 21 Jul, 19 Aug, and 6 Sep, respectively. Soybean rust was first detected in plots at very low levels on 26 Aug, 7 days after the R4 application. By 30 Sep, there was a 100% incidence of soybean rust in the untreated plots. Plots treated at the R2 and R4 stage with Headline SBR or those treated with Headline SBR at R2 followed by Folicur at R4 had a 0% incidence of soybean rust on 30 Sep. Plots treated with Quilt at R2 and R4 had an 87% incidence. An R2 application of Headline SBR resulted in an incidence rating of 25%. Delaying the Headline SBR application to the R5 stage resulted in a 77% incidence rating. Despite the late occurrence of soybean rust in this trial yields were increased with fungicide applications. Regardless of fungicide, plots receiving applications at R2 only or at R2 and R4 had yields at least 9 bu/A more than the untreated check. The yield of plots receiving an application of Headline SBR at R5 was not different from the untreated check. Results from this trial indicate that rust infestations occurring as late as R4 or R5 may still significantly reduce yield. These results also indicate that a late season infestation may be successfully managed by early-season application of fungicides offering residual control.

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