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Potato

General Potato Disease and Pest Management

Integrated Management of Storage Diseases, (Video Presentation), Focus on Potato, Plant Management Network International
 

Diseases

Disease: Bacterial soft rot
Pathogen: Pectobacterium

	Potato tuber with typical soft rot symptoms. (Russet potato cultivar)	Potato seed pieces with soft rot bacteria oozing from cut surfaces. (Russet potato cultivar)	Symptoms of lenticel spot from bacterial infection at the tuber lenticels after washing. (Yellow potato cultivar)
Photo Source: G.Q. Pelter	Photo Source: D. Johnson		Photo Source: B. Gundersen

Puffy appearance of lenticels due to bacterial infection and respiration. (Yellow potato cultivar)	Hard rot symptoms surrounding tuber lenticels. (Russet potato cultivar)	Enlarged lenticels on a tuber, resulting from exposure of the tuber to excessively wet soil conditions. (Russet potato cultivar)
Photo Source: B. Gundersen		Photo Source: D. Johnson

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Bacterial Soft Rot and Blackleg and Lenticel Rot, Oregon State University

Potato: Bacterial soft rot and blackleg, Washington State University Hortsense
 

Disease: Black dot
Pathogen: Colletotrichum coccodes

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Black Dot, Oregon State University

Disease: Black leg
Pathogen: Erwinia species

Potato ‘Norgold’	Potato ‘Ranger Russet’ (mid season symptoms)	Potato ‘Norkotah’ Hail damage 3 days post hail storm as comparison
Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Bacterial Soft Rot and Blackleg and Lenticel Rot, Oregon State University

Potato: Bacterial soft rot and blackleg, Washington State University Hortsense
 

Disease: Black scurf
Pathogen: Rhizoctonia solani

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Rhizoctonia Canker {Black Scurf}, Oregon State University

Potato: Rhizoctonia canker (Black scurf), Washington State University
 

Disease: Corky ring spot
Pathogen: Tobacco rattle virus, transmitted by soilborne nematodes, Trichodorus spp. and Paratrichodorus spp.

	Leaves of the potato cultivar Russet Norkotah with symptoms caused by Tobacco rattle virus.	Foliage of the potato cultivar Shepody with symptoms caused by Tobacco rattle virus.	Poor emergence of plants in a potato crop associated with feeding damage by trichodorid nematodes vectoring Tobacco rattle virus.
Photo Source: G.Q. Pelter	Photo Source: Phil Hamm, OSU Hermiston IAREC

Internal tuber symptoms of corky ringspot.
Photo Source: Jordan Eggers, Oregon State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Corky Ringspot, Oregon State University
 

Disease: Early blight
Pathogen: Alternaria solani

Early blight lesion on tuber.	Early blight lesion on leaf.
Photo Source: G.Q. Pelter	Photo Source: The American Phytopathological Society

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Early Blight, Oregon State University

Early Blight: A Global Management Issue on Potatoes (Video Presentation), Focus on Potato, Plant Management Network International.
 

Disease: Early dying
Pathogen: Meloidogyne and Verticillium

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Verticillium Wilt {Potato Early Dying}, Oregon State University

Potato: Verticillium Wilt (Potato early dying), Washington State University Hortsense

Disease: Erwinia
Pathogen: Erwinia

Potato ‘Ranger Russet’ (early stem symptoms)

Photo Source: G.Q. Pelter

On-Line Resources:

Disease: Fusarium Dry Rot
Pathogen: Fusarium spp.

Photo Source: D. A. Inglis and B. Gundersen

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Fusarium Dry Rot, Oregon State University

Fusarium Dry Rot of Potatoes, Plant Management Network International

Disease: Late Blight
Pathogen: Phytophthora infestans

Photo Source: D.A. Inglis and J. Gigot

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Late Blight, Oregon State University

Organic Management of Late Blight of Potato and Tomato (Phytophthora infestans), eXtension.

Potato Late Blight, Plant Management Network International. (video)

A potato late blight forecasting model for the Columbia Basin can be accessed via the WSU AgWeatherNet website at http://weather.wsu.edu/. Subscription to AgWeatherNet is free of charge.

ARS Scientists Seek Blight-Resistant Spuds, USDA Agricultural Research Service.

Potato Diseases: Late Blight, Extension Bulletin E-2945, Michigan State University.

Disease: Leaf roll (net necrosis symptoms on potato tubers)
Pathogen: Potato leaf roll virus

Primary symptoms.	Net necrosis.	Net necrosis caused by PLRV in steam-peeled tubers of the cultivar Russet Burbank.
Photo Source: G.Q. Pelter		Photo Source: Jordan Eggers, Oregon State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Potato Leafroll Virus {Leaf Roll}, Oregon State University

Potato: Potato leafroll mosaic (Leafroll), Washington State University Hortsense
 

Disease: Mop Top
Pathogen: Potato mop-top virus (PMTV), a pomovirus vectored by the soilborne organism, Spongospora subterrenea. The latter also causes powdery scab (see Powdery scab below)

Symptoms of Potato mop top virus infection of tubers of various potato cultivars.
Photo Source: Jordan Eggers

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Potato Mop-Top Virus, Oregon State University
 

Disease: Pink rot
Pathogen: Phytophthora erythroseptica

Photo Source: G.Q. Pelter	Photo Source: Jordan Eggers, Oregon State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Pink Rot, Oregon State University
 

Disease: Powdery scab
Pathogen: Spongospora subterranea

Symptoms on root.

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Powdery Scab, Oregon State University

Potato: Powdery scab, Washington State University Hortsense

Disease: Pythium
Pathogen: Pythium species

Photo Source: D.A. Inglis

On-Line Resources:

Disease: Pythium leak
Pathogen: Pythium species

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Leak, Oregon State University

Disease: Rhizoctonia stem lesion
Pathogen: Rhizoctonia solani

	Aerial tubers caused by Rhizoctonia stem lesion.
Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Rhizoctonia Canker {Black Scurf}, Oregon State University

Disease: Ring rot
Pathogen: Clavibacter michiganensis subsp. sepedonicus

Advanced foliar symptoms.	Foliar symptoms.
Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Ring Rot, Oregon State University

Potato: Bacterial Ring Rot, UC IPM Online, University of California

Bacterial Ring Rot of Potatoes, Ohio State University Extension Fact Sheet

Recognizing and Managing Bacterial Ring Rot, University of Idaho

AgDia Testing Services
 

Disease: Ring rot and soft rot
Pathogen: Bacterial species

Photo Source: G.Q. Pelter

On-Line Resources:

Potato: Bacterial Soft Rot and Blackleg, UC IPM Online

Disease: Root knot
Pathogen: Meloidogyne species

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Nematode, Root-knot, Oregon State University

Disease: Silver scurf
Pathogen: Helminthosporium solani

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Silver Scurf, Oregon State University

Disease: Skin stain symptoms
Pathogen: Fusarium species

Photo Source: D.A. Inglis

On-Line Resources:

Disease: Tomato spotted wilt
Pathogen: Tomato spotted wilt virus (TSWV)

Foliar symptoms of tomato spotted wilt on a potato plant.
Photo Source: Jordan Eggers and Phil Hamm

On-Line Resources: This disease is more commonly associated with tomato and other crops than with potato.

Pacific Northwest Plant Disease Management Handbook: Tomato (Lycopersicon esculentum) – Tomato Spotted Wilt, See Also: Greenhouse Plants, Ornamental Impatiens Necrotic Spot Oregon State University

Tomato Spotted Wilt Virus, Vegetable MD Online, Cornell University

First Report of Tomato spotted wilt virus Causing Potato Tuber Necrosis in Texas. APS Journals, The American Phytopathological Socitey
 

Disease: Verticillium wilt
Pathogen: Verticillium dahliae
Host crops: Numerous vegetables including many brassica vegetables (but not broccoli), cucumber, eggplant, pepper, potato, pumpkin, radish, spinach, tomato, watermelon, etc.

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Verticillium Wilt {Potato Early Dying}, Oregon State University

Potato: Verticillium wilt (Potato early dying), Washington State University Hortsense

See Diseases, pests, and other problems common to many vegetables: Verticillium wilt.
 

Disease: White mold
Pathogen: Sclerotinia sclerotiorum
Host crops: Bean, various brassica vegetables, carrot, eggplant, lettuce, potato, tomato, etc.

Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – White Mold {Sclerotinia Stem Rot}, Oregon State University

White Mold of Potato: Epidemiology and Management, Plant Management Network International.

See Diseases, pests, and other problems common to many vegetables: White mold.
 

Disease: Zebra chip
Pathogen: Candidatus Liberibacter Solanacearum
Vector: Potato psyllid, Bactericera cockerelli

Foliar symptoms of a potato plant infected with the zebra chip pathogen.	Discoloration inside the main tap root of a potato plant infected by Candidatus Liberibacter.	Pinkish discoloration of the stem end of a tuber.	Brown vascular discoloration of a potato tuber characteristic of zebra chip.
Photo Source: Silvia Rondon, Oregon State University

Cross-section of a potato tuber with zebra chip.	Adult potato psyllid.	Potato psyllid nymph.	Photo tuber post-peeling.
Photo Source: Silvia Rondon, Oregon State University	Photo Source: OSU-HAREC Rondon’s lab (A. Murphy)

On-Line Resources: Information on the Potato psyllid.

History in the Making: Potato Zebra Chip Disease Associated with a New Psyllid-borne Bacterium – A Tale of Striped Potatoes

The Zebra Chip Project, Texas Agrilife Research and Extensioin Center at Amarillo.

Phil Hamm’s message to the industry.
 

Insect/Mite Pests

Common name: Blister beetle
Latin binomial: Epicauta spp. including E. maculata
Host Crops: Blister beetles are typically considered beneficial insects as the larvae feed on grasshopper eggs, but they are occasional pests on crops such as alfalfa, beets, beans, clover, potatoes, other vegetable and field crops, and native plants.

Blister beetles defoliated a short section of an outside row of a potato crop, but did a little damage beyond that. The potato crop was adjacent to rangeland that had a lot of grasshopper eggs on which blister beetle larvae feed.
Photo Source: Sally Hubbs

Adult blister beetle of the species Epicauta pruinosa, which is differentiated from adults of E. fabricii by the second antennal segment: shorter than the third segment on E. pruinosa but longer or equal to the third segment on E. fabricii. E. fabricii has a range south and east of Oregon, while E. pruinosa appears to be common in the Pacific Northwest and has a wider range. The two species produce different levels of cantharin, which is toxic and lethal to cattle.
Photo Source: OSU-HAREC Rondon’s lab (A. Murphy)

On-Line Resources:

Blister Beetles: Coleptera: Meloidae Epicauta maculata, E. fabricii, E. puncticollis, Lytta nutalli. Modified from G. Bishop, et al. 1982. Management of Potato Insects in the Western States, Integrated Plant Protection Center of Oregon State University.

See Diseases, pests, and other problems common to many vegetables: Blister beetle.

 

Common name: Colorado potato beetle
Latin binomial: Leptinotarsa decemlineata (Say).
Host Crops: potato and tomato. Will feed on eggplant, tobacco and weeds in the Solanum genus.

The adult Colorado potato beetle measure about 3/8 inch (8–10 mm), yellowish-orange in color and sometimes called the 10-lined potato beetle.		The mature larva of the Colorado potato beetle measures 1/2 inch long, has a reddish brown body color with two rows of black spots running along the sides, and a black head capsule.
Photo Source: Lerry Lacey, USDA-ARS, Wapato, WA	Photo Source: Michael Bush, WSU Extension, Yakima, WA	Photo Source: Lerry Lacey, USDA-ARS, Wapato, WA	Photo Source: Michael Bush, WSU Extension, Yakima, WA

Colorado potato beetle lays yellow to orange, football-shaped eggs (1/16 inch tall) on the underside of potato leaves. A lacewing larva is grazing on this batch of Colorado potato beetle eggs.

Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Colorado Potato Beetle. Extension Bulletin 0919, Washington State University.

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Colorado potato beetle to Cutworm and Armyworm.

Common Name: Flea beetle
Latin binomial: Pictured is the western potato flea beetle, Epitrix subcrinita, but the tuber flea beetle, Epitrix tuberis, may also damage foliage.
Host crops: Eggplant, pepper, potato, and tomato.

Potato flea beetle damage on potato foliage appears as scallop-like scoops, rounded pits or shotholes originating from the underside of the potato leaf.	The adult flea beetle is small (~1/16 inch long), oblong, and dark brown to bronze in color.	The most distinctive feature of the flea beetle is the enlarged hind legs that provide the insect the ability to jump considerable distances when approached or disturbed.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Potato Flea Beetles: Biology and Control. Washington State University Extension Bulletin 1198E.

Potato Flea Beetles. Coleoptera: Chrysomelidae Western Potato Flea Beetle Epitrix subcrinita, Tuber Flea Beetle Epitrix tuberis

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Flea Beetle to Grasshopper.

Vegetables: Potato: Potato flea beetles. Washington State University Hortsense.

See Diseases, pests, and other problems common to many vegetables: Flea beetle.
 

Common name: Potato psyllid
Latin binomial: Bactericera cockerelli

Adult potato psyllid.	Potato psyllid nymph.
Photo Source: OSU-HAREC Rondon’s lab (A. Murphy)

On-Line Resources: Information on the Potato psyllid.

History in the Making: Potato Zebra Chip Disease Associated with a New Psyllid-borne Bacterium – A Tale of Striped Potatoes

The Zebra Chip Project, Texas Agrilife Research and Extensioin Center at Amarillo.

Phil Hamm’s message to the industry.
 

Common name: Spider mites
Latin binomial: Tetranychus spp. including twospotted spider mite (Tetranychus urticae), strawberry spider mite (Tetranychus turkestani), and Pacific spider mite (Tetranychus pacificus)
Host crops: Wide host range, including many vegetables such as bean, carrot seed crops, potato, etc.

Twospotted spider mite on potato.

Photo Source: Silvia Rondon

On-Line Resources:

Some Common Plant-Feeding Mites and Plant-Inhabiting Mite Predators in the Northwestern United States. PNW Insect Management Handbook.

Lima Bean – Spider Mites. PNW Insect Management Handbook.

Carrot seed – Twospotted spider mite. PNW Insect Management Handbook, Chapter: Vegetable Seed, Section: Carrot Seed.

Managing spider mites in gardens and landscapes. University of California Online Statewide Integrated Pest Management Program.

See See Diseases, pests, and other problems common to many vegetables: Spider mites.
 

Common name (of damaging stage): Tomato hornworm
Latin binomial: Manduca quinquemaculata
Host crops: Pepper, eggplant, potato, and tomato.

Mature tomato hornworms can reach 3 inches long. They come in various hues of green to gray, but are distinguished from other hornworms by the eight v-shaped stripes running along the length of their bodies and a black horn on their rear end. The coloration allows these large caterpillars to remain cryptic within the canopy of tomato plants.	Tomato hornworm is a plant defoliator feeding on entire leaves, small stems, and even parts of immature fruit. Often this defoliation is first noticed near the end of the growing season (August or early September) when the hornworm is approaching maturity.	The tomato hornworm has one generation per year and overwinters as a pupa in the soil. Adults will emerge in the spring.	The tomato hornworm adult is a large (3.5 to 5.25-inch wingspan) moth known as the five-spotted hawk moth for the five pairs of orange spots on the abdomen. The adult is rarely encountered by growers and home gardeners as it tends to fly around dusk.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Pacific Northwest Insect Management Handbook. Washington State Chapter: Vegetables, Section: Tomato Part2: Fleabeetle to Wireworm.

Vegetables: Tomato: Tomato hornworm. Washington State University Hortsense.

UC Pest Management Guidelines: Tomato Hornworms. UC IPM Online, University of California.
 

Common name: Tuberworm
Latin binomial: Phthorimaea operculella.

Tuberworm adults. Female on left, male on right	Potato tuberworm larval damage to potato tubers.
Photo Source: Silvia Rondon

Tuberworm larva.

Photo Source: Lynn Ketchum

On-Line Resources:

Biology and Management of the Potato Tuberworm in the Pacific Northwest. PNW 594

New Emerging Pests in the Pacific Northwest. The Potato Association of America.

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Tuberworm to Wireworm.
 

Common name: Western flower thrips
Latin binomial: Frankliniella occidentalis.
Host crops: Broccoli, Cabbage, Cauliflower, Cucumber, Onion, Potato, Pumpkin, Squash, Tomato and Watermelon.

Closeup of thrips.	Thrips damage on potato leaf.
Photo Source: Silvia Rondon

On-Line Resources:

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Lygus bug to Thrips.

See Diseases, pests, and other problems common to many vegetables: Western flower thrips.
 

Common name (of damaging stage): Wireworm
Latin binomial: Pictured are Limonius spp. (including L. canus and L. californicus). Other wireworm species including Agriotes spp. and Ctenicera spp. can be pestiferous.

Adult wireworm is commonly known as a click beetle. Beetle size 3/8 to 1/2 inch (8–12 mm).	Wireworm larva is dark orange or brown and mature larvae are 3/8 to 1/2 inch in length	Wireworm larvae density can be monitored with oatmeal bait.	Wireworm damage to potato tuber visible as <1/16 inch holes that lead to tunnels beneath the surface.
Photo Source: David Horton, USDA-ARS, Wapato			Photo Source: Andy Jensen, WA Potato Commission

Host Crops: potato, onion, carrot, beet and radish. Although other crops, like corn, beans and peas can be impacted by high densities of wireworms feeding on seedlings resulting in poor crop stands.

On-Line Resources:

WIREWORMS Coleoptera: Elateridae, Pacific Coast Wireworm Limonius canus, Sugarbeet Wireworm L. californicus, Great Basin Wireworm Ctenicera pruinina. Integrated Plant Protection Center of Oregon State University.

Wireworm Biology and Nonchemical Management in Potatoes in the Pacific Northwest. Extension Bulletin PNW 607.

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Tuberworm to Wireworm.