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Research Project:
FUNGICIDE MANAGEMENT FOR SOYBEAN RUST
Location: Soybean/maize Germplasm, Pathology, and Genetics Research
2007 Annual Report
1a.Objectives (from AD-416)
The objective of this cooperative research project is to develop management recommendations for the use of fungicides in post-flowering soybean and to establish fungicide efficacy trials to evaluate both efficacy and phytotoxicity of fungicides on local cultivars to deter potential genotype by fungicide interactions.
1b.Approach (from AD-416)
There are several components that will be evaluated in different experimental programs. The interaction of nozzle type and aperture with pressure, ground speed, or application volume on canopy coverage will be evaluated, as well as the effect of different adjuvants. Kromecote cards and tank-mixed dye will be used in each experiment to determine droplet size and coverage at 75 and 50% of the canopy height. Three cards will be placed across the boom width in three locations at two heights within each plot. Quadris, which is registered for use on soybean and labeled for control of soybean rust, will be used in each experiment unless noted. Obtain information on fungicides in the Section 18 Emergency Exemption Request. Each site will develop an experiment where currently registered Exemption Request are applied to a set of commercial cultivars. The set of cultivars will be selected from the most commonly grown cultivars in each region. The experimental design will be replicated split-plot with three to eight fungicides as the main plots and six to ten cultivars of the sub plots. Plot sizes will be small, 7 to 10 meters in length and four rows wide, with row spacing at 96 cm. Row spacing can be narrower, depending on local production practices. Fungicide applications will be timed for growth stage R2-R3, with a second application 20 days later.
3.Progress Report
This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Louisiana State University. Additional details of research can be found in the report for the parent project 3611-22000-016-00D, Characterization of soybean pathogens and management. The results of this project were based on a total of 157 treatments comprised of 22 fungicides applied in various combinations of rates and times of application. Disease severity was assessed at mid canopy and rated as percentage leaf area affected with the aid of laminated photographs. There were four replications for each treatment, which were arranged in randomized complete blocks. There were many efficacious fungicides for the control of soybean rust, and most had long residual activity. Several fungicides were effective when applied at growth stage R3, but not at growth stage R5. Substantial yield losses were documented even though symptoms were not apparent until after R6. These yield losses occurred in untreated control plots as well as plots that received delayed (R5) applications of effective fungicides. This project was monitored through electronic messages and face-to-face meetings.
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Last Modified: 11/08/2008
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