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Photo Gallery of Vegetable Problems – Carrot


Diseases

Bacterial blight

Bacterial soft rot

Black root rot

Black rot

Cavity spot

Cercospora leaf spot

General Carrot Disease Management

Phytoplasma and spiroplasma
infection (e.g., aster yellows)

Powdery mildew

Rhizoctonia

Violet root rot

White mold (=Cottony rot)

(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 Source: Lindsey du Toit, Washington State University
Photo Source: Lindsey du Toit, Washington State University

Online Resources:

Quantitative Molecular Detection ofXanthomonas hortorum pv, carotaein 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 Erwiniaspp.)

Photo Source: G.Q. Pelter Photo Source: Bo-Ming Wu, Oregon State University
Photo Source: Jeremiah Dung, Oregon State University Photo Source: Lindsey du Toit, Washington State University Photo Source: Jeremiah Dung, Oregon State University
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

Online Resources:

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

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

Black root rot on stored carrots.
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 Source: E. J. Sorensen Photo Source: Pacific Northwest seed company field representative

Online 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 Source: Lindsey du Toit, Washington State University

Online Resources:

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

Disease: Cercospora leaf spot
Pathogen: Cercospora carotae

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
Photo Source: Lindsey du Toit, Washington State University

Online 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 Source: G.Q. Pelter Photo Source: Lindsey J. du Toit

Online 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 Source: Lindsey du Toit Photo Source: E. J. Sorensen

Online Resources:

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

 

Disease: Rhizoctonia
Pathogen: Rhizoctonia solani

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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.

Photo Source: Lindsey du Toit, Washington State University

 

Online Resources:

http://pnwhandbooks.org/plantdisease/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, lettucepotatotomato, etc.

Photo Source: Lindsey du Toit, Washington State University

Online 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 Source: E. J. Sorensen Photo Source: Lindsey du Toit, Washington State University

 

Online 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

 

Online 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, spinachSwiss 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 Source: Lindsey du Toit, Washington State University Photo Source: Bev Gerdeman, WSU Entomologist

Online 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.

Severe outbreak of spider mites in a carrot seed crop in central Washington.
Photo Source: Lindsey du Toit Photo Source: Silvia Rondon, Oregon State University

 

Online 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: Potatoonion, 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 Source: Tom Brown Photo Source:Lindsey du Toit, Washington State University Photo Source: Oregon State University – Oregon State Arthropod Collection.

Online 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, onionpepper, potato, tomato, and many other crops (not only vegetables)

Photo Source: Lindsey du Toit, Washington State University

Online 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.

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