Plant Disease Management Handbook

See:

Bean, All (Phaseolus vulgaris) - Curly Top

See:

Alfalfa (Medicago sativa) - Alfalfa Mosaic

By C. M. Ocamb and D. H. Gent

See:

Bean, Snap (Phaseolus vulgaris) - White Mold (Sclerotinia Rot)

Image related to Bean, Dry (Phaseolus vulgaris)-White Mold (Sclerotinia Rot)

White mold on bean stems, notice the black sclerotia on the lower left stem.

Photo by Bob Forster

White mold on bean stems, notice the black sclerotia at the base of the plant.

Photo by Bob Forster

Cause Pythium debaryanum and P. ultimum are fungus-like microorganisms that persist indefinitely in soil or plant debris. Favored by wet soils, they increase when vegetable and legume crops are planted too frequently in the rotation.

See:

Bean, All (Phaseolus vulgaris) - Damping-off and Stem Rot

By C. M. Ocamb and D. H. Gent

Cause Pseudomonas syringae pv. phaseolicola, a bacterium that overwinters primarily in seed but can survive in infected, undecomposed plant debris from the previous year's crop. Rain, irrigation water, tools, equipment, and humans can spread the bacterium. The frequent wet weather in Oregon's Willamette Valley in June favors the development and spread of halo blight.

Image related to Bean, All (Phaseolus vulgaris)-Halo Blight

Note the yellow color around the necrotic centers.

Photo by Paul Koepsell, 1986.

The first symptom is water-soaked spots followed by irregular brown spots.

Larry Moore collection, 1987.

The first symptom is water-soaked spots followed by irregular brown spots, usually with yellow halos around them.

Larry Moore collection.

On the pods, dark, greasy-looking, water-soaked spots appear that extend through the pod and become dry and brown.

Larry Moore collection.

Irregular brown spots, usually with yellow halos around them.

Larry Moore collection, 1969.

Cause Pythium spp., Rhizoctonia solani, and Fusarium spp., possibly other pathogens can cause a seed rot and seedling blight known as damping-off. These soilborne fungi or fungus-like microorganisms can persist indefinitely in soil or plant debris. Rhizoctonia can be transmitted on seed. Damping-off is favored by wet soils.

Cause Beet curly top virus (BCTV) is spread by the beet leafhopper. Other crop hosts include sugar beet, watermelon, tomato, annual flowers, and cucurbit. The disease is cyclic but occurs frequently in the Columbia Basin, southern Idaho, and central Oregon. The virus overwinters in wild perennial or winter annual hosts and is not seedborne.

By D. H. Gent and C. M. Ocamb

Leaf spots enlarge and merge, becoming dried and brown with a narrow, bright lemon-yellow border that encircles the lesion.

Larry Moore collection.

Infected pods develop circular water-soaked spots that later dry and become reddish-brown, sunken lesions.

Larry Moore collection.