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Poster Presentations


Poster Presentations


The impact of Asian soybean rust and other diseases on soybean treated with selected fungicides

Presenter: Guy B Padgett

Other authors and affiliations: . Louisiana State University Agricultural Center, Northeast Research Station, Winnsboro, LA 71295, U.S.A.

In 2006, soybean diseases reduced overall production in Louisiana 3.16 million bushels or 11%. Prior to 2004, strobilurin and benzamidiazole chemistries were the foundation of fungicide programs; however, the recent introduction of Asian soybean rust (ASR) in Louisiana has raised questions about the effectiveness of these programs on ASR. Tests were conducted in Jefferson Davis (producer field) and Rapides (Dean Lee Research Station) parishes to evaluate selected fungicides on ASR disease progress; efficacy on Cercospora blight, aerial blight, and pod diseases; and soybean yield and quality. Aerial or ground applications of fungicides were applied once or twice during the reproductive stages (R1 to R5). Disease incidence and severity were assessed during the growing season. Soybean was harvested to assess treatment effects on yield and quality when possible. Triazoles were more efficacious against ASR than were strobilurin chemistries, but differences were noted among the triazoles. In general, ASR severity did not appreciably increase in triazole treatments until 41 days after application, compared with 34 days in strobilurin treatments. Strobilurin products performed best against aerial blight, while thiophanate methyl provided the best protection against Cercospora blight. No single fungicide class provided broad-spectrum disease control; therefore, tank mixes of several classes will be needed for effective management. Yields from fungicide treatments were 417% more than the nontreated. Fungicides can be used to effectively manage soybean diseases in Louisiana, but more research will be needed to determine the impact of application number, application timing, and disease initiation on soybean yield and quality.

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