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United States Department of Agriculture

Agricultural Research Service

Title: Evaluations of Fungicides for Control of Soybean Rust in the Cultivar ‘prima 2000’ Near Cedara, South Africa, 2004-05

Authors
item Miles, Monte
item Hartman, Glen
item Rij, N. Van - DEPT. OF AG-SOUTH AFRICA
item Tweer, S - DEPT. OF AG-SOUTH AFRICA
item DE Preez, E - DEPT. OF AG-SOUTH AFRICA
item Lawrance, K - DEPT. OF AG-SOUTH AFRICA

Submitted to: Fungicide and Nematocide Tests
Publication Type: Trade Journal
Publication Acceptance Date: December 6, 2005
Publication Date: January 10, 2006
Citation: Miles, M.R., Hartman, G.L., Rij, N., Tweer, S., De Preez, E., Lawrance, K. 2006. Evaluations of fungicides for control of soybean rust in the cultivar ‘prima 2000’ near Cedara, South Africa, 2004-05. Fungicide and Nematocide Tests. Report 61: FC002. DOI:10.1094FN61.

Interpretive Summary: An important aspect to the management of soybean rust is the use of fungicides. This study evaluated fungicide efficacy using two and/or three applications at one location in South Africa. Soybean rust was rated as a percentage of leaf area affected within the center two rows of each plot. Plots were harvested and yields were calculated. Soybean rust was first observed in the plots 93 days after planting. There were significant differences among the treatments for accumulated rust severity, 1000 seed-weights and yield. All fungicide treatments had significantly lower disease severity and greater 1000 seed weights than the unprotected control. All fungicides had greater yields than the unprotected control. There were no differences between the means of the 2-application and 3-application programs for 1000 seed-weights or yield but there was a significant difference for rust severity as the 2-application program had greater rust severities. This information is useful for those interested in managing soybean rust, and includes soybean growers, industry personnel and crop consultants.

Technical Abstract: Fungicide trials for the management of soybean rust were done in Cedara, South Africa during the 2003-04 growing season. The experimental design was a split plot with four replications. The main effects were fungicide treatment, i. e. product and rates, with 2- and 3-application programs as the subplots. Plots were 8 rows wide, with 4 rows receiving fungicide applications. The two center rows of each plot were harvested, with a harvest length of 5.0 M. Fungicides were applied with a battery-operated-pressured backpack sprayer, Lurmark hollow cone ceramic (ATR80), a horizontal spray-boom, and two nozzles spaced 50 cm apart. Full cover of 20 gal/A at 3 bars of pressure was applied per row. The first application was made at growth stage R1, 69days after planting (DAP) with subsequent applications 22 days apart. Soybean rust was rated as a percentage of leaf area affected in canopy within the center two rows of each plot on each date of evaluation and used to produce an area under disease progress curve (AUDPC). The data was not transformed since preliminary analysis indicated it was not warranted. Plots were harvested 157 DAP on 21 April 05, and yields were calculated as bu/A at 13% moisture.

Last Modified: 9/10/2014
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