Soybean Rust
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Asian soybean rust can be difficult to diagnose, particularly on older leaves. Itís symptoms are not as distinct as those caused by other species of rusts seen on other plant species. The underside of leaves can be examined under high magnification for the presence of volcano-like spore-producing structures (pustules). A microscopic examination of the pustules will show the presence of spores with fine spikes on the outside. Texas A&M plant pathologists in all soybean-producing areas of the state are trained in the diagnosis of this disease and should always be consulted to confirm a diagnosis.

^Top of leaf

^Bottom of leaf, showing rust lesions.

^Detail of asian soybean rust spore, showing fine spikes on the outside of the spore.

^Underside of leaf, slightly magnified, showing angular lesions caused by rust infection.

^Magnification of rust lesion, showing detail of pustules, where spores of the fungus are produced. Pustules have openings and can resemble little volcanoes.

^Magnification of a rust pustule, showing masses of spores.
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