Submitted to: Pesticide Outlook
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2003
Publication Date: 4/11/2003
Citation: Miles, M.R., Hartman, G.L., Levy, C., Morel, W. 2003. Current status of sobyean rust control by fungicides. Pesticide Outlook. 14:197-200. Interpretive Summary: With the movement of soybean rust into major soybean production areas with the exception of the U.S., the use of fungicides in soybeans has increased. It would be expected that if soybean rust entered the continental U.S.A., there would be another dramatic increase of fungicides used on soybean. It is not known what kind of application methods would predominate in the U.S.A., but aerial application has been the primary method in Brazil and Paraguay with some fungicides applied with ground equipment. Multiple application methods are being used in Southern Africa, with the most effective methods being those where penetration and canopy coverage are the greatest. Since cropping systems, field sizes, and total area that may need fungicides varies by country, the methods that provide the best canopy penetration and coverage and most effective in the control of rust are the ones that will predominate. Information related to control of soybean rust is useful to the soybean producer, ag consultants, and chemical applicators.
Technical Abstract: The Asian soybean rust, caused by Phakopsora pachyrhizi, had been limited to the Eastern hemisphere until it was found in Hawaii in 1994. Currently, the distribution of P. pachyrhizi includes Africa, Asia, Australia, South America, and Hawaii. The pathogen is readily disseminated by wind-borne urediniospores and can drastically reduce yields. The primary tool in the control of the disease will be the use of fungicides. In this research, timing and number of applications of fungicides were tested. The most efficient for controlling soybean rust were applications applied during early reproductive growth, which allowed protection through to crop maturity. The exact number of applications will depend on the length of the reproductive phase of the crop, duration of the compound and severity of the epidemic. Fungicide applications in early vegetative stages, although effective in reducing disease severity, were not shown to be effective in protecting yield.