News that soybean rust has been discovered in the United States for the first time, heightens the need for awareness and education about the disease among agricultural producers and affiliated industries.

USDA and the Kansas State University Research and Extension Plant Pathologist Doug Jardine, provide the following is information about the disease and where it came from.

What to Look For: Small lesions may be visible on the lower leaves of an infected plant. These will increase in size and change from gray to tan or reddish brown on the undersides of the leaves. Lesions are most common on leaves, but may occur on petioles, stems and pods.

Soybean rust produces two types of lesions, tan and reddish brown. Tan lesions, when mature, consist of small pustules surrounded by slightly discolored necrotic area with masses of tan spores on the lower leaf surface. Reddish brown lesions have a larger reddish brown necrotic area, with a limited number of pustules and few visible spores on the lower leaf surface.

Once pod set begins, infection can spread rapidly to the plant's middle and upper leaves.

Where Did It Come From? Asian soybean rust was first observed in Japan in 1902, and was found throughout most Asian countries and in Australia by 1934. It currently is found in Africa, Asia, Australia
and South America. Because the disease spores are carried by the wind, it was expected to make its way to the United States from South America.

USDA, Kansas State University

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