Organizing Committee


Poster Presentations


Poster Presentations


Efficacy of organic-compliant treatments for Asian soybean rust

Presenter: Kathleen Delate(1)

Other authors and affiliations: Ann Blount(2), Cheryl Mackowiak(2), David Wright(2), Robert Turnbull(1). (1)Iowa State University, Departments of Agronomy and Horticulture, Ames, IA 50011, U.S.A.; (2)University of Florida, Department of Agronomy, Quincy, FL 32353, U.S.A.

Research conducted in 2006 at the University of Florida (UF) examined the effect of selected organic-compliant sprays on Asian soybean rust and soybean yields. Research at Michigan State University, The Rodale Institute, and Iowa State University (ISU) evaluated the effect of these products on yields and diseases other than ASR, such as Cercospora and bacterial blight. ‘Hinson Long Juvenile’ soybeans were planted on June 20, 2006, in organic transition plots in Quincy, FL. Eight treatments were evaluated and The Horsfall-Barrett Scale was used for rating ASR damage on a scale of 1–12, with 1 equaling no damage and 12 equaling 100% of leaves infected. The most effective treatments were Champion® wettable powder (Nufarm, Burr Ridge, IL), containing 77% copper hydroxide, and basic copper sulfate, which led to damage levels on leaves of 3% or lower. Similarly, yields in the copper treatments were superior to the other treatments. Copper buildup in the leaves and soil is being monitored by UF scientists. Buildup in organic systems should be mitigated, however, because of the following: (i) organic soybeans should be planted once every 3–4 years in the rotation according to certified organic rules; (ii) a cover crop of rye or alfalfa that is cut and composted following sprayed soybeans may mitigate copper accumulation in the soil; and (iii) a minimal application rate of copper at strategic times will help reduce the chance of copper accumulation. Research is continuing in 2007 and 2008.

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