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Pests & Diseases
Aphids can damage crops throughout production; insects will feed on the carrot and serve as a vector for other diseases. Rootknot nematodes feed on roots, causing stunted growth and deformation. Populations are typically largest around harvest time.

To control the carrot rust fly, experts recommend eradicating weeds as a common breeding place. Avoid crop rotation with other susceptible vegetables such as parsnips and celery.

Other harmful pests include beetles, caterpillars, crickets, fire ants, fleahoppers, leafhoppers, spittlebugs, stink bugs, thrips, weevils, and whiteflies, all of which can be particularly damaging to seeds and in all stages of plant development.

Pythium blight may result in stubbing, root forking, dieback, or the growth of white mycelium fungus that may develop into watery soft rot under moist conditions. Rhizoctonia is a bacterial infection that causes brownish-black lesions on the taproot. The disease is exacerbated by wet, cool conditions and is best prevented by crop rotation and good agricultural practices.

Cavity spot is soilborne and may lead to loss of an entire crop. It can be identified by brown, water-soaked lesions that expand and dry as the carrot matures. Cavity rot is more likely in fields with prior carrot or alfalfa plantings.

Other diseases include anthracnose, leaf black root, canker, damping off, leaf spot, mold (grey, white), mosaic viruses, root knot, root rot, and types of scab.

Storage & Packaging
Cool water washes and hydrocooling are necessary to remove field heat after harvest. Carrots will dry out quickly, with white striations appearing on the outside surface as moisture is lost. Topped carrots should be stored in 95 to 100% humidity at 32°F. Carrots are also sensitive to ethylene, which will cause bitterness.

Due to having similar storage requirements, carrots can be stored in mixed loads with other vegetables such as asparagus, broccoli, cauliflower, lettuce, radishes, and spinach among others.

References: North Carolina State University Extension, University of California Vegetable Research & Information Center, University of Florida/IFAS Extension, University of Georgia Extension, University of Illinois Extension, USDA, Washington State University Extension.


Carrots are classified into topped or bunched with additional requirements for grade levels. For topped, U.S. Extra No. 1 require a diameter of not less than .75 inches or more than 1.5 inches with a length of not less than 5 inches; U.S. No. 1 are the same as for Extra No. 1 except it is possible to specify sizes both within and outside of the diameter range, and lengths both longer and shorter than 5 inches.

For U.S. No. 1 Jumbo carrots, requirements include a diameter not less than 1 inch or more than 2.5 inches, with a minimum length of 5 inches; U.S. No. 2 require a diameter 1 to 3 inches with a minimum length of 3 inches.

For bunched carrots, U.S. No. 1 requires a diameter of at least .75 inches unless otherwise specified, and the length of tops to be no more than 20 inches unless otherwise specified. High-quality carrots will be firm, straight, brightly colored, hairless (no root hairs), moist, and free from green shoulders or bitterness.

Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.


U.S. Grade Standards Days Since Shipment % of Defects Allowed Optimum Transit Temp. (F)
10-5-1 5


U.S. Grade Standards Days Since Shipment % of Defects Allowed Optimum Transit Temp. (F)
10-5-2 5

There are no good arrival guidelines specific to Canada for bunched carrots; there are guidelines for topped carrots—unless otherwise noted, they are broken down into five parts as follows: maximum percentage of defects, maximum percentage of permanent defects, maximum percentage for any single permanent defect, maximum percentage for any single condition defect, and maximum for decay. Canadian destination guidelines are 15-10-5-10-4.

References: DRC, PACA, USDA.


• There are size requirements for carrots: unless otherwise specified, U.S. No. 1 Topped Carrots shall be not less than 1 inch, or more than 3 inches in diameter, or less than 3 Inches in length
• Air cracks or fresh cracks are scored as a defect when the length of the crack exceeds 20% of the total carrot length, is deeper than 1/4 inch, or is wider than 1/8 inch
• New root growth or top growth (on topped carrots) is scored as a condition defect when materially affecting the appearance. As a guide, new top growth is scored as a defect when the length of new growth is greater than 1 inch in length.

Source: Tom Yawman, International Produce Training,

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