Pacific Northwest Vegetable Extension Group

of Washington State University, Oregon State University, and University of Idaho

Photo Gallery of Vegetable Problems

Potato

(Click on photo to enlarge)

General Potato Disease and Pest Management

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

Diseases

Disease: Aster yellows
Pathogen: Aster yellows phytoplasma
Vector: Aster leafhopper (Macrosteles fascifrons) and other leafhoppers, and the phytoplasma can be carried in infected tubers
Host crops: Over 300 kinds of plants, including a wide variety of vegetables. Broccoli, cabbage, carrot, onion, potato, pumpkin, radish, shallot, spinach, squash, tomato, and more.

Photo of aster yellows symptoms on potato
Potato plant with a seed-borne infection of the aster yellows phytoplasma.
Photo Source: Carrie Wohleb, WSU Extension Educator, Grant/Adams Counties

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Aster Yellows {Late-breaking Virus}

Pacific Northwest Plant Disease Management Handbook: Aster – Yellows
 

Disease: Bacterial soft rot
Pathogen: Pectobacterium

Photo of Bacterial soft rot on potato Photo of potato tuber with typical soft rot symptoms Photo of potato seed pieces with soft rot bacteria oozing from cut surfaces Photo of symptoms of lenticel spot from bacterial infection at the tuver lenticels after washing
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
Photo showing puffy appearance of lenticels due to bacterial infection and respiration Photo of hard rot symptoms surrounding tuver lenticels Photo of enlarged lenticels on a tuber resulting from exposure of the tuber to excessively wet soil conditions.
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

Bacterial Soft Rot and Lenticel Spot on Potato Tubers, Washington State University Extension Fact Sheet.

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

Potato Progress, Volume 15, Number 12, dated September 8, 2015. Research & Extension for the Potato Industry of Idaho, Oregon, and Washington. This issue covers the many details of bacterial soft rot diseases of potato and how they should be managed late season and in storage.
 

Disease: Black dot
Pathogen: Colletotrichum coccodes

Photo of Black dod on potato
Photo Source: G.Q. Pelter

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Black Dot

Disease: Black leg
Pathogen: Erwinia species

Photo of Black leg on potato 'Norgold' Photo of Black leg (mid-season symptoms) on potato 'Ranger Russet' Photo of hail damage on Potato 'Norkotah' as a comparison
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:

‘Focus on Potato’ Webcast Helps Users Minimize Spread of Blackleg

Blackleg, caused by strains of soft rot bacteria known as Dickeya, has traditionally had little impact on North American potato production, but it now appears to be on the move throughout Europe and could threaten growers in the United States.

The Plant Management Network (PMN) has released a presentation entitled “Dickeya: A Scottish, UK and European Perspective” to provide growers and consultants an overview of the history of the disease in Europe, and an introduction to Dickeya solani, a new aggressive pathogen strain contributing to an increase in the incidence and spread of blackleg. The webcast was developed by Gerry Saddler, Deputy Head of Science & Advice Scottish Agriculture with the Scottish Government, and details that country’s potato production practices and explains why they have adopted a national zero-tolerance approach to the presence of Dickeya strains. The presentation discusses:

Causes of blackleg and symptoms exhibited by different strains

Conditions that encourage infection and common transmission methods

Inspection and testing practices employed in Scotland

Effective control measures to limit spread

The 40-minute presentation will remain open access through July 31 in the Focus on Potato webcast resource. The Plant Management Network is a nonprofit publisher of applied, science-based resources that help enhance the health, management, and production of agricultural and horticultural crops. Partnering with over 80 universities, nonprofits, and agribusinesses, PMN provides materials covering a wide range of crops and contemporary issues through the online PMN Education Center.

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

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

Potato Progress, Volume 15, Number 12, dated September 8, 2015. Research & Extension for the Potato Industry of Idaho, Oregon, and Washington. This issue covers the many details of bacterial soft rot diseases of potato and how they should be managed late season and in storage.

Soft Rot and Blackleg Diseases of Potato, Plant Management Network International

Disease: Black scurf
Pathogen: Rhizoctonia solani

Photo of Black scurf on potato
Photo Source: D.A. Inglis

On-Line Resources:

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

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.

Photo of Corky ring spot on potato 'Russet Burbank' Photo of Corky ring spot on potato leaves Photo of corky ring spot on potato leaf Photo of poor emergence of potato plants associated with feeding damage by nematodes vestoring Tobacco rattle virus
  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
Photo of Corky ring spot on potato potato-trv-6
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
 

Disease: Curly top
Pathogen: Beet curly top virus (BCTV), vectored by the beet leafhopper Circulifer tenellus
Host crops: Numerous plant species including many vegetables such as bean, beet, carrot, eggplant, coriander, pepper, potato, tomato, and various cucurbits such as squash, cucumber, pumpkin, watermelon, etc.

Photo of curly top on tomato Photo of tomato plants showing symptoms of beet curly top virus Photo of tomato plants showing symptoms of beet curly top virus Photo of tomato plants showing symptoms of beet curly top virus
Symptoms of curly top on tomato leaves.
Photo Source: E. J. Sorensen Photo Source: Phil Hamm, Oregon State University
Photo of tomato plants showing symptoms of beet curly top virus Photo of tomato plants showing symptoms of beet curly top virus
Symptoms of curly top on tomato leaves.
Photo Source: Krishna Mohan, University of Idaho

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Green Dwarf {Curly Top}
 

Disease: Early blight
Pathogen: Alternaria solani

Photo of Early blight lesion on tuber Photo of Early blight lesion on leaf
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


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

Focus on Potato webcast: “Best Management Tactics and Fungicide Resistance in Early Blight and Brown Spot” by Dr. Lydia Tymon, plant pathologist at Washington State University.
 

Disease: Early dying
Pathogen: Meloidogyne and Verticillium

Photo of Early dying on potato
Photo Source: G.Q. Pelter

On-Line Resources:

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

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

Disease: Erwinia
Pathogen: Erwinia

Photo of early stem symptoms of Erwinia on potato
Potato ‘Ranger Russet’ (early stem symptoms)
Photo Source: G.Q. Pelter

On-Line Resources:

Disease: Fusarium Dry Rot
Pathogen: Fusarium spp.

Photo of Fusarium dry rot on potato Photo of Fusarium dry rot on potatoes

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

On-Line Resources:

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

Fusarium Dry Rot of Potatoes, Plant Management Network International

Disease: Late Blight
Pathogen: Phytophthora infestans

Photo of late blight stem sporulation on potato Photo of late blight lenticel sporulation on potato Photo of late blight seed pc transmission Photo of late blight lesion on foliage Photo of late blight of potato tuber

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

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Late Blight

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

Photo of primary symptoms Photo of net necrosis Photo of net necrosis Photo of net necrosis
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}

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)

Photo of potato mop top virus infection Photo of potato mop top virus infection Photo of potato mop top virus infection
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
 

Common Name: Pink eye of potato
Latin binomial: Unknown causal agent, occasionally observed in white- and russet-skinned cultivars, but not red-skinned cultivars. The disease has been associated with some bacteria, and is reported to be more severe in cultivars susceptible to Verticillium wilt.

Photo of possible pink eye of potato Photo of symptoms of pink eye of potato tubers Photo of symptoms of pink eye of potato tubers Photo of symptoms of pink eye of potato tubers
Suspected symptoms of pink eye of potato. Symptoms of pink eye of potato tubers.
Photo Source: Karen Ward, Washington State University Plant Diagnostician. Photo Source: Jordan Egger, Oregon State University
Photo of symptoms of pink eye of potato tubers Photo of symptoms of pink eye of potato tubers Photo of symptoms of pink eye of potato tubers
Symptoms of pink eye of potato tubers. A potato tuber illuminated with ultraviolet light, glowing as a result of pink eye.
Photo Source: Jordan Egger, Oregon State University

On-Line Resources:

Potato – Pink Eye or Brown Eye, Vegetable MD Online, Cornell University

Pink Eye of Potato, Prince Edward Island Department of Agriculture and Forestry, Canada

Relationship of Verticillium Wilt with Pink-Eye of Potato in Maine, USDA National Agricultural Library’s Digital Collections
 

Disease: Pink rot
Pathogen: Phytophthora erythroseptica

Photo of Pink rot on potato 'Russet Burbank' Photo of pink rot of potato Photo of pink rot of potato Photo of pink rot of potato
 
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
 

Disease: Powdery scab
Pathogen: Spongospora subterranea

Photo of POwdery scab on potato Photo of powdery scab on potato
Symptoms on root. Note raised lesions on the tuber surface where the epidermis has broken away to expose dark, powdery masses.
Photo Source: G.Q. Pelter Photo Source: Babette Gundersen

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Powdery Scab

Potato: Powdery scab, Washington State University Hortsense

Disease: Purple Top
Pathogen: Beet leafhopper transmitted virescence agent (BLTVA), a phytoplasma
Vector: Beet leafhopper (Circulifer tenellus), and the phytoplasma can be carried in infected tubers.

Photo of symptoms on a stem and leaves of a potato plant with BLTVA
Symptoms on a stem and leaves of a potato plant infected with BLTVA as a result of current-season infection.
Photo Source: Pete Thomas, USDA-ARS Prosser

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Purple Top

Disease: PVY
Pathogen: Potato virus Y (PVY), a virus transmitted mechanically and by insects (aphids)

Photo of symptoms of PVY on potato leaves Photo of symptoms of PVY on potato Photo of symptoms of PVY on potato Photo of symptoms of PVY on potato Photo of symptoms of PVY on potato
Symptoms on leaves of the potato cultivar Atlantic infected with Potato virus Y. Foliar mosaic symptoms caused by PVY on potato cultivars Ranger, Burbank, and Alturas (in order left to right). Necrotic leaf spots caused by PVY on the potato cultivar Yukon Gold.
Photo Source: Jordan Eggers, Oregon State University
Photo of symptoms of PVY on potato Photo of symptoms of PVY on potato Photo of PVY symptoms of PVY infection on the potato clutivar Canela Russet Photo of PVY symptoms of PVY infection on the potato clutivar Canela Russet Photo of PVY symptoms of PVY infection on the potato clutivar Canela Russet potato-PVY-11
Foliar ring spots caused by PVY on the potato cultivar Yukon Gold. Leaf vein necrosis caused by PVY on the potato cultivar Alturas. Symptoms of PVY infection on the potato cultivar Canela Russet.
Photo Source: Jordan Eggers, Oregon State University Photo Source: Carrie Wohleb, WSU Extension Educator for Grant/Adams Counties
Photo of severe symptoms of Potato virus Y infection on the potato cultivar Chieftain Photo of severe symptoms of Potato virus Y infection on the potato cultivar Chieftain
Severe symptoms of Potato virus Y infection on the potato cultivar Chieftain.
Photo Source: Babette Gunderson, Washington State University

On-Line Resources:

Seedborne Potato Virus Y (PVY), Identification & Management of Emerging Vegetable Problems in the Pacific Northwest. Pacific Northwest Vegetable Extension Group.

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Latent Viruses
 

Disease: Pythium
Pathogen: Pythium species

Photo of Pythium on potato
Photo Source: D.A. Inglis

On-Line Resources:

Disease: Pythium leak
Pathogen: Pythium species

Photo of Pythium leak on potato
Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Leak

Disease: Rhizoctonia stem lesion
Pathogen: Rhizoctonia solani

Photo of Rhizoctonia stem lesion on potato Photo of aerial tubers caused by Rhizoctonia stem lesion.
  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}

Disease: Ring rot
Pathogen: Clavibacter michiganensis subsp. sepedonicus

Photo of Ring Rot (advanced foliar symptoms) on potato Photo of Ring rot (foliar symptoms) on potato Photo of bacterial ring rot on potato Photo of bacterial ring rot on potato
Advanced foliar symptoms. Foliar symptoms. Severe symptoms of bacterial ring rot on a Russet Burbank seed tuber. Note discolored, cheesy consistency of the tuber’s vascular ring and the dry gray pockets of decayed tissue surrounding it.
Photo Source: G.Q. Pelter Photo Source: Jordan Eggers, Oregon State University Photo Source: Babette Gundersen

On-Line Resources:

Bacterial Ring Rot on Potatoes, Washington State University Extension Fact Sheet FS102E

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Ring Rot

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 of Ring rot and soft rot on potato
Photo Source: G.Q. Pelter

On-Line Resources:

Bacterial Soft Rot and Lenticel Spot on Potato Tubers, Washington State University Extension Fact Sheet.

Potato: Bacterial Soft Rot and Blackleg, UC IPM Online

Soft Rot and Blackleg Diseases of Potato, Plant Management Network International

Disease: Silver scurf
Pathogen: Helminthosporium solani

Photo of silver scurf on potato
Photo Source: D.A. Inglis

On-Line Resources:

Silver Scurf Management in Potatoes, Oregon State University, University of Idaho, Washington State University

Pacific Northwest Plant Disease Management Handbook: Potato (Solanum tuberosum) – Silver Scurf

Disease: Skin stain symptoms
Pathogen: Fusarium species

Photo of Skin stain symptoms on potato
Photo Source: D.A. Inglis

On-Line Resources:

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

Photo of Tomato spotted wilt on potato Photo of Tomato spotted wilt on potato
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

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 of Verticillium wilt on potato
Photo Source: G.Q. Pelter

On-Line Resources:

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

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 of White mold on potato
Photo Source: G.Q. Pelter

On-Line Resources:

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

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

Photo of zebra chip symptoms on potato leaves Photo zebra chip symptoms on potato stem Photo zebra chip symptoms on potato tuber exterior Photo zebra chip symptoms on potato tuber interior
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
Photo of zebra chip symptoms on potato tuber interior Photo of Potato psyllid adult Photo of Potato psyllid nymph Photo of zebra chip symptoms on potato tuber
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)
Photo of zebra chip symptoms on potato leaves Photo of zebra chip symptoms in potato tuber Photo of zebra chip symptoms in potato tubers  
Early foliar symptoms of a potato plant infected with the zebra chip pathogen. Tuber showing characteristic symptoms of zebra chip. Tubers showing symptoms of zebra chip.  Healthy tuber shown on the right.  
Photo Source: Carrie H. Wohleb, WSU  

On-Line Resources: Information on the Potato psyllid.

Potato Psyllid Vector of Zebra Chip Disease in the Pacific Northwest: Biology, Ecology, and Management, PNW 633.

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 Extension Center at Amarillo.

Phil Hamm’s message to the industry.
 

Nematodes

Disease: Root knot
Pathogen: Meloidogyne species
Host crops: Numerous plant species, including many vegetables such as carrot, coriander, onion, potato, etc.

Photo of root knot on potato Photo of root knot on potato

Photo Source: G.Q. Pelter

On-Line Resources:

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

See Diseases, pests, and other problems common to many vegetables: Root knot
 

Insect/Mite Pests

Common name: Green peach aphid and potato aphid
Latin binomial: Myzus persicae and Macrosiphum euphorbiae, respectively
Host crops: In addition to potato, tomato, eggplant and pepper, the green peach aphid can feed on many other vegetables including broccoli, cabbage, spinach, Swiss chard, squash, pumpkin, beet as well as many weed species including Brassicaceae (cruciferous) weeds. The potato aphid can feed on cucumber, potato, melon, tomato, pumpkins, squash, and corn seed.

Photo of green peach aphid nymph on leaf Photo of green peach aphid Photo of aphid damage on leaf
Green peach aphid may be found along the midrib on the underside of leaves of a host plant. Mature aphids are about 2 mm long (ca. 1/16 inch), egg-shaped, and the color of the wingless nymphs and adults ranges from pinkish yellow to yellowish green. There are usually multiple individuals in a single colony. The green peach aphid tends to overwinter in stone fruit trees. By late May to early June, individual aphids in a colony develop wings and fly to vegetable crops and a wide range of weeds. As the aphids disperse (June to August), they can transmit important viruses including potato leaf roll virus and potato virus Y. The easiest way to scout for aphid colonies is to search perimeter vegetable plants for copious amounts of sticky, glistening honeydew coating the upper surfaces of lower leaves of plants. Honeydew may contain numerous cast (shed) skins (white to gray) and a black sooty mold (fungus) that colonizes aphid honeydew.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Pacific Northwest Insect Management Handbook: Vegetable crop pests-Aphid

Pacific Northwest Insect Management Handbook: Potato, Irish – Aphid

Common Insect & Mite: Aphids, Washington State University Hortsense.

See Diseases, pests, and other problems common to many vegetables: Aphids

For aphids on other crops see: pumpkin, and squash
 

Common Name: Beet leafhopper
Latin binomial: Circulifer tenellus
Host crops: Wide host range, including many vegetables. The Beet leafhopper is able to transmit a phytoplasma, the beet leafhopper transmitted virescence agent (BLTVA), to plants such as potato, carrot, and radish. It can also transmit the curly top virus to plants such as bean, tomato, pepper, pumpkin, and squash.

Photo of beet leafhopper
The adult beet leafhopper is a small, wedge-shaped insect, approximately 1/8 inch long.
Photo Source: Andy Jensen, Washington Potato Commission

On-Line Resources:

Pacific Northwest Insect Management Handbook: Potato, Irish – Leafhopper

Potato: Beet Leafhopper, UC IPM Online, University of California
 

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.

Photo of blister beetle damage to potato Photo of blister beetle damage to potato Photo of blister beetle damage to potato Photo of blister beetle on potato
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
Close-up photo of blister beetle Close up photo of blister beetle
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.

Blister Beetles, Identification & Management of Emerging Vegetable Problems in the Pacific Northwest. Pacific Northwest Vegetable Extension Group.

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.

Photo of adult Colorado potato beetle Photo of adult Colorado potato beetle Photo of mature larval Colorado potato beetle Photo of colorado potato beetle larva
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
Photo of adult Colorado potato beetle
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.

Photo of potato flea beetle damage on potato foliage Photo of adult potato flea beetle Photo of adult potato flea beetle showing enlarged hind legs
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, 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; psyllid yellows
Latin binomial: Bactericera cockerelli; Psyllid yellows is said to be caused by a toxin in the saliva of psyllid nymphs as they feed on potato plants. The condition is still poorly understood and some have argued it might be caused by a pathogen (e.g., a phytoplasma or bacterium) in the saliva that has not yet been characterized. Studies have shown recovery of potato plants after removal of psyllids, which supports the toxin theory.

Photo of Potato psyllid adult Photo of Potato psyllid nymph Severe symptoms of psyllid yellows on the new growth of potato plants, caused by potato psyllids feeding on the plants. Severe symptoms of psyllid yellows on the new growth of potato plants, caused by potato psyllids feeding on the plants.
Adult potato psyllid. Potato psyllid nymph. Severe symptoms of psyllid yellows on the new growth of potato plants, caused by potato psyllids feeding on the plants.  
Photo Source: OSU-HAREC Rondon’s lab (A. Murphy) Photo Source: Carrie Wohleb, WSU Extension Educator

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.

Potato Psyllids, Zebra Chip, Psyllid Yellows, WSU Potato Pest Alert, August 26, 2016
 

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.

Photo of twospotted spider mite Eggs of the two-spotted spider mite, Tetranychus urticae.
Twospotted spider mite on potato. Eggs of the two-spotted spider mite, Tetranychus urticae.
Photo Source:Silvia Rondon, Oregon State University


On-Line Resources
:

Potato – 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.

Photo of mature tomato hornworm Photo of tomato hornworm Photo of tomato hornworm on ground Photo of tomato hornworm adult
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. Tomato Hornworm.

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.

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

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

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

On-Line Resources:

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: 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.
Host Crops: Potato, onion, carrot, beet, spinach seed crops and radish. Other crops, like corn, beans and peas can be impacted by high densities of wireworms feeding on seedlings resulting in poor crop stands.

Photo of wireworm adult Photo of wireworm larva Photo of monitoring wireworm density Photo of wireworm damage to potato
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
A click beetle of the species Agriotes obscurus, the larvae of which are wireworms. A click beetle of the species Limonius californicus, the larvae of which are wireworms. A click beetle of the species Limonius canus, the larvae of which are wireworms.
A click beetle of the species Agriotes obscurus, the larvae of which are wireworms. A click beetle of the species Limonius californicus, the larvae of which are wireworms. A click beetle of the species Limonius canus, the larvae of which are wireworms.
Photo Source: Oregon State University – Oregon State Arthropod Collection.


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: Wireworm.

Wireworm Field Guide - A guide to the identification and control of wireworms, Syngenta Crop Protection Canada, Inc.

Wireworm Biology and Nonchemical Management in Potatoes in the Pacific Northwest, N. Andrews, M. Ambrosino, G. Fisher, and S.I. Rondon, Pacific Northwest Extension Publication no. PNW607

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


Abiotic Problems Common to Potato


Common name: 2,4-D herbicide drift injury
Cause: Drift of the broadleaf herbicide 2,4-D into potato crops.
Host Crops: Most broadleaf plants are susceptible to injury by 2,4-D.

Title Title
Symptoms of injury from drift of the herbicide 2,4-D into a potato crop.
Photo Source: Carrie H. Wohleb, Washington State University

Online Resources:

2,4-D- and Dicamba-tolerant Crops— Some Facts to Consider


Problem: Herbicide carryover in potato seed
Crops affected: Most, if not all, crops can be affected by herbicides used to control weeds.

Photo of excessive sprouting caused by carrover on potato seed Photo of blank areas in a field due to herbicide carryover on potato seed tubers. Photo of potato sprouts branching underground (arrow) and excessive root production Photo of stunted potato plant with deformed leaves due to herbicide carry-over on seed
Excessive sprouting caused by herbicide carryover on potato seed. Blank areas in a field due to herbicide carryover on potato seed tubers. Rows on the right are plants from seed not contaminated with herbicide. Potato sprouts branching underground (arrow) and excessive root production caused by herbicide carryover on the seed tubers Stunted potato plant with deformed leaves due to herbicide carry-over on seed.
Photo Source: Carrie Wohleb, WSU

On-Line Resources:

Herbicide Carryover in Potato Seed. Identification & Management of Emerging Vegetable Problems in the Pacific Northwest, Pacific Northwest Vegetable Extension Group.


Common name: Air pollution or ozone injury
Cause: During very hot conditions, combined with the presence of excessive air particulate matter, e.g., from wildfires, symptoms of air pollution and/or ozone injury have been observed in center-pivot irrigated potato crops east of the Cascade Mountains in the Pacific Northwest USA.
Host Crops: Potato and other vegetables, e.g., bean and corn.

Title Title Title Title
Possible symptoms of ozone or air pollution injury to potato crops.
Photo Source: Carrie H. Wohleb, Washington State University Extension
Title
Possible symptoms of ozone or air pollution injury to potato crops.
Photo Source: Carrie H. Wohleb, Washington State University Extension

 

Problem: Physiological leaf roll
Cause: Various environmental conditions and management practices
Crops affected: Tomato and Potato.

Photo of Physiological leaf roll on tomato Photo of Physiological leaf roll on tomato Photo of Physiological leaf roll on tomato

Photo Source: PNW VEG members

On-Line Resources:

Physiological Leaf Roll of Tomato/Potato, Identification & Management of Emerging Vegetable Problems in the Pacific Northwest. Pacific Northwest Vegetable Extension Group.

Physiological Leaf Roll of Tomato, A Fact Sheet prepared by The Pacific Northwest Vegetable Extension Group


 

Problem: Toxic seed piece syndrome
Crop affected: Potato.

Photo of a typical potato seed piece associated with TSPS Photo of remnant of a potato seed piece still attached to the stem Photo of ascular discoloration in the potato stem just above where the seed piece was attached Photo of potato leaves showing interveinal chlorosis and bronzing
A typical potato seed piece associated with TSPS. Remnant of a potato seed piece still attached to the stem. Vascular discoloration in the potato stem just above where the seed piece was attached. Potato leaves showing interveinal chlorosis and bronzing.
Photo Source: Phil Hamm, OSU Photo Source: Carrie Wohleb, WSU Photo Source: Phil Hamm, OSU Photo Source: Carrie Wohleb, WSU
Photo of symptomatic potato plant showing wilting symptoms Photo of ymptomatic plant showing wilt symptoms Photo of potato field with several plants showing TSPS symptoms
Potato leaves showing interveinal chlorosis and bronzing. Symptomatic plant showing wilt symptoms. Potato field with several plants showing TSPS symptoms.
Photo Source: Carrie Wohleb, WSU Photo Source: Phil Hamm, OSU Photo Source: Carrie Wohleb, WSU

On-Line Resources:

Toxic Seed Piece Syndrome (TSPS). Identification & Management of Emerging Vegetable Problems in the Pacific Northwest, Pacific Northwest Vegetable Extension Group.




 

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