Plant Disease Management Handbook

By K. Frost and C. M. Ocamb

See:

Potato (Solanum tuberosum) - Potato Virus Y

Image related to Potato (Solanum tuberosum)-Latent Viruses

This plant is infected with PVY.

Photo by Phil Hamm.

Leaves showing symptoms of PVY infection.

Photo by Phil Hamm.

Frontier' plant infected with PVY.

Photo by Phil Hamm.

Tuber pieces showing symptoms of PVY infection.

Photo by N. Bell, OSU Extension, 2010.

By P. B. Hamm and C. M. Ocamb

Image related to Potato (Solanum tuberosum)-Late Blight

Late blight symptoms on leaves.

Photo by Phil Hamm

Note the discoloration in the tissue beneath the skin.

Photo by Phil Hamm.

Stem hits are common.

Photo by Phil Hamm.

Sporulation on the leaf undersurface.

Photo by Phil Hamm.

This tuber has late blight symptoms.

Photo by Phil Hamm.

Sporangia of Phytophthora infestans

Photo by Phil Hamm.

Cause Sugar beet curly top virus causes this disease and the virus is transmitted by the sugar beet leafhopper. In Oregon, the disease is found primarily in eastern Oregon but is also occurs in central Oregon and the Klamath Falls area. The disease essentially parallels the distribution of the sugar beet leafhopper.

Cause Several Fusarium sp., including F. avenaceum, F. oxysporum, and F. solani. These fungi survive in infected plant parts as well as be soilborne for many years.

Cause Several Fusarium spp., including F. sambucinum, F. solani var. coeruleum and F. avenaceum, have been known to can cause dry rot of potato tubers. A recent study published by the Univeristy of Idaho reports that additional Fusarium species are pathogenic on tubers, including F. cerealis, F. culmorum, F.

Image related to Potato (Solanum tuberosum)-Fusarium Dry Rot

Photo by Phil Hamm.

Note the dry rot with a whitish mold.

Photo by Phil Hamm.

By C. M. Ocamb and P. B. Hamm

See:

Potato (Solanum tuberosum) - Brown Spot and Black Pit

Image related to Potato (Solanum tuberosum)-Early Blight

Note the small, brown, slightly angular lesions on the foliage.

Photo by Cynthia M. Ocamb, 1998.

Ranger Russet' with severe early blight symptoms.

Photo by Cynthia M. Ocamb, 1998.

Classical early blight lesions on potato leaflets.

Photo from OSU Extension Plant Pathology Slide Col

Both early blight and late blight lesions on can be seen on these potato leaves.

Photo from OSU Extension Plant Pathology Slide Col

Early blight lesions on a potato tuber.

Photo from OSU Extension Plant Pathology Slide Col

Early blight symptoms on a potato tuber.

Photo from OSU Extension Plant Pathology Slide Col

Potato tubers showing extensive infection by Alternaria.

Photo by Ken Frost, OSU, 2018.

By K. Frost and C. M. Ocamb

See:

Potato (Solanum tuberosum) - Nematode, Stubby-root

Image related to Potato (Solanum tuberosum)-Corky Ringspot

Tubers show the variation in corky ringspot symptoms.

Photo by Kenneth Rykbost.

There is much variation in the symptoms of corky ringspot.

Photo by Kenneth Rykbost.

Note the discolored areas and arcs within the tuber tissue.

Photo by Kathy Merrifield, 1990.

Notice the variation in the corky ringspot symptoms.

Photo by Kenneth Rykbost.

Gnarled tubers of 'Russett Burbank' with corky ringspot.

Photo by Kenneth Rykbost, 1992.

By P. B. Hamm and C. M. Ocamb

Image related to Potato (Solanum tuberosum)-Scab, Common

Note the roughened exterior of these tubers.

Photo part of OSU Extension Plant Pathology Slide Collection

Scab symptoms on a potato tuber.

Photo from OSU Extension Plant Pathology Slide Collection

Cause The alfalfa mosaic virus is carried in tubers, but aphids can transmit it from alfalfa plants to potato plants by feeding first on infected plants and then probing noninfected plants. Nearby alfalfa fields or volunteer infected alfalfa plants in potato fields can be a source of inoculum.

Symptoms Large, irregular, yellow to cream-color spots appear on leaves. Tubers may show internal brown necrotic areas.

Image related to Potato (Solanum tuberosum)-Calico

Note the yellow leaves symptomatic of calico disease.

Photo part of OSU Extension Plant Pathology Slide

Potato plant with calico symptoms.

Photo by Ken Frost, 2017.

Potato plant showing calico symptoms.

Photo by Ken Frost, 2021.

Note the mosaic pattern in leaves.

Photo by Cynthia M. Ocamb, 1998.

Cause A physiological disorder associated with low moisture content of the tuber at harvest, bruising, low storage temperatures, and potash deficiency. Bruising increases rapidly when the pulp of potatoes being harvested drops below 47°F to 50°F (8.33°C to 10°C). Desiccation (pressure flatting) increases black spot when potatoes are handled.

Symptoms Internal black spots usually are at the tuber's stem end. White, smooth-skinned varieties are more susceptible.

Image related to Potato (Solanum tuberosum)-Black Spot (Internal Black Spot)

Photo by Phil Hamm