Pacific Northwest Vegetable Extension Group

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

Photo Gallery of Vegetable Problems

Carrot

(Click on photo to enlarge)

Diseases

General Carrot Disease Management

Various root rots of carrots. Dr. Caterina Saude and Dr. Mary K. Hausbeck, Department of Plant Pathology, Michigan State University, Carrot Country, Summer 2006

Disease: Bacterial blight
Pathogen: Xanthomonas hortorum pv. carotae (formerly Xanthomonas campestris pv. carotae)

Photo of bacterial leaf blight of a carrot Photo of bacterial leaf blight of carrot Photo of bacterial leaf blight. Photo of bacterial leaf blight of carrot Photo of bacterial leaf blight of carrot
         
Photo Source: Lindsey du Toit, Washington State University
Photo of bacterial leaf blight of carrot Photo of bacterial leaf blight of carrot
  Close-up view of bacterial blight lesions showing watersoaking and chlorosis around the lesions.
Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

Quantitative Molecular Detection of Xanthomonas hortorum pv, carotae in Carrot Seed Before and After Hot-Water Treatment. Plant Disease 97:1585–1592.

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Bacterial Leaf Blight

Pacific Northwest Vegetable Association Annual Meeting presentation: “Bacterial blight of carrot: Management and Detection” by Lindsey du Toit.
 

Disease: Bacterial soft rot
Pathogen: Various bacteria including Dickeya spp. and Pectobacterium spp. (formerly Erwinia spp.)

Photo of Bacterial soft rot of a carrot root Photo of bacterial soft rot on carrot Photo of wilting of carrot foliage due to soft rot. Photo of bacterial soft rot on carrot
  Soft rot of the root of a plant in a carrot seed crop following early spring cold injury to the roots. Wilting of foliage in a carrot seed crop as a result of soft rot of the roots preventing adequate translocation of water to the foliage. Severe wilting and dieback of plants in a carrot seed crop as a result of soft rot of the roots.
Photo Source: G.Q. Pelter Photo Source: Bo-Ming Wu, Oregon State University
Death of plants in the female row of a hybrid Kuroda carrot seed crop as a result of bacterial soft rot. A plant wilting and dying in a carrot seed crop as a result of soft rot of the root. Note the black lesion extending up the stem from the soil line. Black lesion extending up the stem from the soil line as a result of infection by Pectobacterium carotovorum. Symptoms of bacterial soft rot of carrot roots.
Death of plants in the female row of a hybrid Kuroda carrot seed crop as a result of bacterial soft rot. A plant wilting and dying in a carrot seed crop as a result of soft rot of the root. Note the black lesion extending up the stem from the soil line. Black lesion extending up the stem from the soil line as a result of infection by Pectobacterium carotovorum. Symptoms of bacterial soft rot of carrot roots.
Photo Source: Jeremiah Dung, Oregon State University Photo Source: Lindsey du Toit, Washington State University Photo Source: Jeremiah Dung, Oregon State University
Photo of bacterial soft rot on carrot Photo of Bacterial soft rot of a carrot root Photo of bacterial soft rot on carrot
Severe pitting of carrot roots caused by soft rot bacteria, observed after the roots were harvested and washed. Severe pitting of carrot roots caused by soft rot bacteria, observed after the roots were harvested and washed.
Photo Source: Lindsey du Toit, Washington State University Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Soft Rot {Core Soft Rot}
 

Disease: Black root rot
Pathogen: Thielaviopsis basicola (= Chalara elegans)

Title
Black root rot on stored carrots.
Photo Source: Lindsey du Toit, Washington State University

Online Resources:

Black root rot. University of Massachusetts Amherst, Agriculture & Landscape Program, Vegetable Program, Soil, Crop & Pest Management

Disease: Black rot
Pathogen: Alternaria radicina

Photo of Black rot on carrot Photo of Black rot on carrot Photo of Black rot on carrot

(symptoms on crown)
Photo Source: E. J. Sorensen

Photo Source: Pacific Northwest seed company field representative

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Black Rot


Disease: Cavity spot
Pathogen: Pythium spp. such as P. violae and P. sulcatum

Photo of symptoms of cavity spot on carrot Photo of symptoms of cavity spot on carrot
 
Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Cavity Spot

Disease: Cercospora leaf spot
Pathogen: Cercospora carotae

Photo of symptoms of leaf spot Photo of symptoms of cercospora leaf spot on carrot stalk Photo of cercospora leaf spot on carrot leaves Photo of leaf spot on carrot Photo of cercospora leaf spot on carrot leaf
 
Photo Source:
D.A. Inglis
Photo Source: Lindsey du Toit,
Washington State University
Photo Source: D.A. Inglis Photo Source:
Lindsey du Toit, Washington State University
Closeup of cercospora leaf spot on carrot Photo of cercospora carotae under microscope Photo of cercospora carotae under microscope
  Microscope photo of spores of the fungus Cercospora carotae. Microscope photo of spores of Cercospora carotae produced on the surface of a lesion.
Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Cercospora Leaf Blight

Carrot: Leaf spot, Washington State University

Carrot Leaf Blight, Vegetable MD Online, Cornell University

Leaf Blights or Spots of Carrot, Universion of Illinois Extension

Management of Carrot Leaf Diseases, Ontario Ministry of Agriculture, Food and Rural Affairs
 

Disease: Phytoplasma and spiroplasma infection (e.g., aster yellows)
Pathogen: Various types of phytoplasmas and spiroplasma, e.g., Aster yellows phytoplasma, Beet leafhopper transmitted virescence agent (BLTVA), and Spiroplasma citri

Photo of Aster yellow on carrot Photo of Aster Yellows on carrot Photo of Aster Yellows on carrot Photo of Aster Yellows on carrot Photo of Aster Yellows on carrot
    Phytoplasma infection of carrot showing hairy roots and purple-bronze foliage. Normal carrot seed umbels (left) vs. umbels showing symptoms of phyllody and virescence (right) as a result of infection by a phytoplasma. Symptomatic (left) vs. asymptomatic (right) parts of an umbel from a carrot seed crop as a result of infection by a phytoplasma.
Photo Source: G.Q. Pelter Photo Source: Lindsey J. du Toit

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Aster Yellows

Aster leafhoppers in carrots, Live barley near carrots when leafhoppers may be present increases the number of leafhoppers and their potential to spread aster yellows phytoplasma. Integrated Pest Management Resources, Michigan State University

Disease: Powdery mildew
Pathogen: Erysiphe heraclei

Photo of powdery mildew on carrot Photo of powdery mildew on carrot Photo of powdery mildew on carrot Photo of powdery mildew spores Photo of powdery mildew on carrot

Photo Source: Lindsey du Toit

Photo Source: Lindsey du Toit

Photo Source: E. J. Sorensen

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Powdery Mildew


Disease: Rhizoctonia
Pathogen: Rhizoctonia solani

Photo of Rhizoctonia on carrot
Photo Source: E. J. Sorensen

Online Resources:

 

Disease: Violet root rot

Pathogen: Rhizoctonia crocorum (sexual stage = Helicobasidium brebissonii)

Host crops: Violet root rot has been reported on carrot, celery, fennel, parsley, and parsnip within the Umbelliferae. However, the fungus reportedly has a wide host range that includes asparagus, artichoke, alfalfa, bean, beet, cabbage, clover, dandelion, mangel, potato, rape, rhubarb, sugar beet, sweet potato, and turnip as well as numerous weed species.

Severe symptoms of violet root rot on carrot. Close-up view of severe violet root rot on a carrot. Note the fan-like hyphae of the pathogen, Rhizoctonia crocorum, growing on the root surface.
Severe symptoms of violet root rot on carrot. Close-up view of severe violet root rot on a carrot. Note the fan-like hyphae of the pathogen, Rhizoctonia crocorum, growing on the root surface.
Photo Source: Lindsey du Toit, Washington State University

Online Resources:

https://pnwhandbooks.org/plantdisease/host-disease/carrot-daucus-carota-violet-root-rot

http://www.omafra.gov.on.ca/english/crops/facts/98-001.htm#Violet%20root%20rot

http://www.plantprotection.hu/modulok/angol/root_veg/violet_root.htm


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

Photo of white mold of carrot: matted foliage Photo of dieback of carrot from whitemold Photo of white mold on carrot root

Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) Cottony Rot

Carrot: Cottony Rot (White Mold). Howard F. Schwartz and David H. Gent, Colorado State University

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

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 nematode on carrot Photo of galls cause by root knot nematode Photo showing resistant vs. susceptible cultivar
  Galls caused by root knot nematode. The root of a carrot cultivar partially resistant to root knot nematode (left) vs. the root of a highly susceptible cultivar (right).
Photo Source: E. J. Sorensen Photo Source: Lindsey du Toit, Washington State University

 

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Carrot (Daucus carota) – Nematode, Root-knot

Carrot: Root-knot nematode, Washington State University Hortsense

Major Emerging Problems with Minor Meloidogyne Species. By Axel A. Elling, Washington State University, Phytopathology Review.

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

Insect/Mite Pests

Common name: Carrot rust fly
Latin binomial: Psila rosae
Host crops: Carrot, parsnip, celeriac, celery, turnip and other umbelliferous crops, including the weed, hemlock.

Feeding damage from the carrot rust fly with a larva emerging from the feeding site.
Feeding damage from the carrot rust fly with a larva emerging from the feeding site.
Photo Source: Mike Derie, Washington State University

On-Line Resources:

Vegetable crop pests-Carrot rust fly. Pacific Northwest Insect Management Handbook, Oregon State University

Carrot Rust Fly Biology & Management. Nick Andrews, Small Farms, Oregon State University

Carrot: Carrot rust fly, Use IPM (Integrated Pest Management) for successful plant problem management. Hortsense, Carrie Foss, Pesticide Education, Art Antonelli, Extension Entomology, WSU Puyallup

Managing Carrot Rust Fly - In Search of Alternatives for a Tough Customer. Dr. David Muehleisen, Andrew Bary, Dr. Craig Cogger, Dr. Carol Miles, Amanda Johnson and Dr. Marcia Ostrom, WSU, and Terry Carkner, Terry’s Berries Organic Farm, Agrichemical and Environmental News, March 2003

Intercropping in Carrots for Rust Fly Control. Carol Miles, Ph.D.,WSU Extension, Leslie Zenz, Research Assistant, Betsie DeWreede, Owner, Independence Valley Farm, and Julie Puhich, Owner, Common Ground CSA, Mount Vernon Northwestern Washington Research and Extension Center, Vegetable Research and Extension

Carrot Rust Fly - Life Cycle and Habits. Carrot Insects, Ontario Ministry of Agriculture, Food and Rural Affairs Factsheet 93-077

Carrot rust fly. Plant Health Australia Factsheet


Common name
: Lygus bugs
Latin binomial: Lygus spp.
Host crops: Numerous different species of vegetables and other crops, e.g., alfalfa, beet, cabbage, carrot, spinach, Swiss chard, etc. Lygus bugs can cause different types of damage to various growth stages of different crops. They cause blackheart on celery, blasting on flower tissues, collapse of asparagus spears, decreased yields in carrot, beet, spinach, and other seed crops, etc.

Photo of people sweeping for lygus bugs in a carrot seed crop Photo of a lygus bug on a Swiss chard plant
Sweeping for lygus bugs in a carrot seed crop during bloom to determine appropriate management practices. A lygus bug on a Swiss chard plant. Note the wing pads developing on the insect.
Photo Source: Lindsey du Toit, Washington State University Photo Source: Bev Gerdeman, WSU Entomologist

On-Line Resources:

Pacific Northwest Insect Management Handbook: Carrot seed – Lygus bug
 

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 spider mite on carrot seed crop Photo ofspider mite on carrot seed crop Two-spotted spider mite adult and eggs on a potato leaf. Eggs of the two-spotted spider mite, Tetranychus urticae.
Severe outbreak of spider mites in a carrot seed crop in central Washington. Two-spotted spider mite adult and eggs on a potato leaf. Eggs of the two-spotted spider mite, Tetranychus urticae.
Photo Source: Lindsey du Toit Photo Source: Silvia Rondon, Oregon State University

On-Line Resources:

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

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


 

Common name: Wireworm
Latin binomial: 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 carrot showing wireworm and symptoms of wireworm damage onion-wireworm-5 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: Tom Brown Photo Source: Lindsey du Toit, Washington State University Photo Source: Oregon State University – Oregon State Arthropod Collection.

On-Line Resources:

Vegetable crop pests – Wireworm. PNW Insect Management Handbook

Wireworms. Ontario Ministry of Agriculture and Food

Managing Wireworms in Vegetable Crops. VegEdge, University of Minnesota

http://whatcom.wsu.edu/ag/homehort/pest/wireworm.htm. Washington State University

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.


 

Parasitic Plants

Common name: Field dodder
Latin binomial: Cuscuta spp.
Host Crops: Bean, beet, carrot, onion, pepper, potato, tomato, and many other crops (not only vegetables)

Photo of field dodder on carrot Photo of field dodder on carrot Photo of field dodder on carrot Photo of field dodder on carrot
Dodder haustoria. Dodder coiled on carrot leaves. Dodder on carrot. Dodder patch.
Photo Source: Lindsey du Toit, Washington State University

On-Line Resources:

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

Abiotic Problems Common to Carrot

Problem: Split roots
Cause: Wide fluctuations in soil moisture and growth rate of carrot roots, particularly early in the growth stage. Splitting can lead to secondary bacterial infections.
Crops affected: Beet, carrot, parsnip, radish and other root crops.

Photo of severe splitting of a carrot root
Severe splitting of
a carrot root.
Photo Source: Tom Brown

On-Line Resources:

See Root vegetables: splitting. Royal Horticultural Society


 

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WSU Mount Vernon NWREC, 16650 State Route 536, Mount Vernon, WA 98273-4768, 360-848-6120
Contact Us: Lindsey du Toit and Carol Miles