Plants of the dry bean variety "Fisher Pinto," showing symptoms of bean rust (Uromyces appendiculatus).

Plants of the dry bean variety "Chase Pinto," showing no sign of bean rust (Uromyces appendiculatus).

Dermont Coyne and Rennie Stavely examing rust (Uromyces appendiculatus) on drybeans (Phaseolus coccineus) at Tamulipas, Honduras.

A drybean rust (Uromyces appendiculatus) nursery at Zamorano, Honduras.

A team of researchers at a drybean rust (Uromyces appendiculatus) nursery at Zamorano, Honduras.

Rust (Uromyces appendiculatus) reaction on the dry bean varieties UI126 and Bill Z.

Plots used by Colorado State University to research pesticide use against bean rust (Uromyces appendiculatus).

Spot inoculation of a dry bean leaflet with rust (Uromyces appendiculatus) urediniospores.

A type of stone texture at Honduras where a workshop on bean rust diseases was held.

A scenic view of a city street of Tamulipas in Honduras.

Microphotograph of the germinating tubes of rust  spores (Uromyces appendiculatus)  on a dry bean leaf.

Rust aecium (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Rust pycnia (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Rust pycnia (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Rust pycnia (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Rust pycnia (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Rust (Uromyces appendiculatus) aecia and pycnia on the leaves of a volunteer dry bean plant.

Aecium of bean rust (Uromyces appendiculatus) on the petiole of a volunteer dry bean plant.

Aecia of bean rust (Uromyces appendiculatus) on the stems of volunteer dry bean plants.

Pycnia of rust (Uromyces appendiculatus) on the leaf of a volunteer dry bean plant.

Aecia of bean rust (Uromyces appendiculatus) on the stem of a dry bean plant inoculated in the greenhouse.

Pycnia and aecia of bean rust (Uromyces appendiculatus) on the stems of dry bean plants inoculated in the greenhouse.

Aecia of bean rust (Uromyces appendiculatus) on the stem of a dry bean plant inoculated in the greenhouse.

Telia of bean rust (Uromyces appendiculatus) on the stem of a bean plant.

Telia of bean rust (Uromyces appendiculatus) on the leaf of a bean plant.

Uredia and necrosis on a bean leaf, due to infection with bean rust (Uromyces appendiculatus).

Blisters (young uredia) on bean leaves, due to infection with bean rust (Uromyces appendiculatus).

"Harvesting" the urediniospores of bean rust (Uromyces appendiculatus) from bean leaves in the greenhouse.

Aecia of rust (Uromyces appendiculatus) on the leaf of a volunteer bean plant.

Rust uredia (Uromyces appendiculatus) on the underside of bean leaflets.

Rust telia (Uromyces appendiculatus) on stems and pods of bean plants in the field.

Leaves of volunteer bean plants infected with the pycnia, aecia, and uredia of bean rust.

Leaves of volunteer bean plants infected with young and mature uredia of bean rust.

Uredinia of bean rust (Uromyces appendiculatus) on the leaves of plants in the field.

Uredinia of bean rust (Uromyces appendiculatus) on plants, causing wilting of the bean canopy in the field.

Bean leaves displaying the "green island effect" of bean rust (Uromyces appendiculatus).

Rust (Uromyces appendiculatus) focal point in a field of dry beans.

Symptoms of bean rust (Uromyces appendiculatus) on the pinto bean cultivar "UI114."

Symptoms of bean rust (Uromyces appendiculatus) on the pinto bean cultivar "Cahone."

Early symptoms of bean rust (Uromyces appendiculatus) in a field, showing the focal location of infection.

Advanced symptoms of bean rust (Uromyces appendiculatus) in a field, showing the focal location of infection.

Advanced symptoms of bean rust (Uromyces appendiculatus) in a field.

Portions of dry bean leaves demonstrating various sizes of rust pustules (Uromyces appendicultus) on the upper and  under surfaces of leaves.

Jim Groth examing rust (Uromyces appendiculatus) on wild drybeans (Phaseolus vulgaris) in the wild.

Rust (Uromyces appendiculatus) on wild drybeans (Phaseolus vulgaris) in the wild at Tamulipas, Honduras.

Close-up view of the pycnium of bean rust (Uromyces appendiculatus).

Close-up view of a pycnium and an aecium of bean rust (Uromyces appendiculatus).

Bean leaf showing symptoms of rust (Uromyces appendiculatus) in variety trials conducted by Colorado State University.

Field of dry beans displaying prominent symptoms of bean rust (Uromyces appendiculatus) near Ovid, Colorado.

Rust (Uromyces appendiculatus) infection of a snap bean plant.

Bean plants severely infested with rust (Uromyces appendiculatus).

A volumteer drybean plant showing symptoms of the rust fungus Uromyces appendiculatus.

Symptoms of dry bean rust (Uromyces appendiculatus) after spot inoculation of a leaf in the laboratory, demonstrating a susceptible reaction.

Reaction of bean plants to rust (Uromyces appendiculatus) in a variety trial in the field.