Submitted to: Plant Disease Management Reports
Publication Type: Other
Publication Acceptance Date: 9/19/2007
Publication Date: 10/7/2007
Citation: Mueller, T.A., Miles, M.R., Hartman, G.L., Morel, W. 2007. Evaluation of fungicides and fungicide timing for the control of soybean rust at Capitan Meza, Paraguay, 2006. Plant Disease Management Reports.1=FC062.
Technical Abstract: About 9000 soybean seeds were planted at Capitán Meza, Paraguay on 10 Jan 2006 in four row plots, 24 ft long, with 18-in. row spacing and two rows of border. The experimental design was a randomized complete block with four replicates. Treatments consisted of Headline 2.09EC, Folicur 3.6F, Quilt 1.67SC applied at growth stages R1, R3, R5 with either one, two or three applications; Folicur 3.6F and Headline 2.09EC together or in sequence. Fungicides were applied at 64, 87, and 107 days after planting (DAP) at 15 gal water per acre with a hand-operated backpack sprayer fitted with a pressure regulator set to 40 psi and equipped with TeeJet XR8002 flat fan nozzles spaced 20-in. apart. Soybean plants were rated for soybean rust in the lower, middle, and upper canopy. The rating scale used was a 0 to 9 severity scale where a rating of “0” had no rust and “9” had severe symptoms. The average of the lower, middle, and upper canopy was used for analysis. The middle two rows of each plot were harvested at 126 DAP and the yield was adjusted to 13 percent moisture. Soybean rust was first observed 87 DAP, so the first fungicide applications was applied as a protectant and the second and third applications were applied curatively. There were significant differences among treatments for soybean rust severity, seed weight, and yield. There was significantly less soybean rust than the untreated control for 16 of the 23 treatments, 19 of the 23 treatments had greater seed weight than the untreated control, and 17 of the 23 treatments had higher yield than the untreated control. No phytotoxicity was observed for any treatments.