Long, slender Imperator-type varieties are desired for fresh market. Blunt-tipped Nantes varieties are preferred for sliced, processed products, and blocky Chantenay or Danvers types are used for dicing. Cultivars vary in susceptibility to aster yellows. See Reference 1.

Organically Managed Carrot Variety trial results 2005 text | photos

Table of carrot disease resistant varieties

Planting Methods

Carrots are a cool-season crop that can tolerate light frosts. Good quality roots (judged by length, shape, and color) develop when soil temperature is between 60° and 70°F. At warmer temperatures, the roots will be shorter, and internally the color will be lighter orange.

Carrots are biennial, normally producing an enlarged root the first growing season and, after a prolonged cold period (below 45°F), a seedstalk (assuming that the roots are not allowed to freeze). When spring conditions are especially cool, bolting or premature seedstalk development can occur during the first growing season. If this happens, the root will be woody and inedible. Because large seedlings are more susceptible to bolting than are smaller seedlings, premature seedstalk development is generally associated with early spring plantings. Varieties differ greatly in their susceptibility to bolting.

The length of carrot roots is determined within the first few weeks after germination because the taproot quickly penetrates deep into the soil. If the young taproot is injured, it will become branched and forked, making the root unmarketable. Excessive soil moisture, insects, diseases, nematodes, and soil compaction can all markedly affect root quality. Wet soil near harvest will cause the roots to become rough and promote root rot diseases.

Obtaining long, straight, smooth roots is difficult. Light-textured soils that contain few stones or well-drained muck soils are preferred. Primary tillage should be fairly deep, but care must be taken not to impair soil structure by working the soil when wet. Use of raised beds, which tend to increase drainage, aeration, and total depth of tilled soil, can improve the length and shape of roots.

Some carrot varieties (Nantes and related types) are especially susceptible to the formation of chlorophyll (green pigment) on the shoulders and within the core area of the root. To reduce this problem, the soil should be hilled over the shoulders of the roots at the last cultivation.

Table 16.1 Recommended spacing.
Type	Row (inches)	In-row (3 lines at)	Seed (lb/acre)
Imperator or Nantes	18-36	1.5"	2 to 3
Chantenay or Danvers	18-36	1.5"	1 to 2

Crop rotation and disease management article

Fertility

Maintain a pH of 6.0 to 6.5 on mineral soils; consider liming when the pH falls below 5.2 on muck soils. See Table 16.2 for the recommended rates of nitrogen, phosphorus, and potassium.

Cornell cover crop decision tool

See Cornell article on nutrient deficiency symptoms

Go to Cornell Nutrient Analysis Lab website to find out how to get soil samples tested.

Cornell Soil Health website and manual

SARE Publication: "Building Soils for Better Crops"

SARE publication: "Managing Cover Crops Profitably"

Table 16.2 Recommended nutrients based on soil tests.
	P2O5 pounds/acre     Soil Phosphorus Level				K2O pounds/acre     Soil Potassium Level
N pounds/acre								Comments
	low	med.	high		low	med.	high
80-90	120	80	40		160	120	60	Total recommended.
30-40	80	40	0		120	80	20	Broadcast and disk-in.
20	40	40	40		40	40	40	Drill deep after disking or band place with planter.
30	0		0		0	0	0	Sidedress 4-6 weeks after seeding. Sidedress twice in years with heavy rainfall.

Harvesting

Machine harvesters are used for the processing crop and for roots that are marketed in polyethylene bags. Bunching carrots are hand harvested and tied together.

Carrots can be stored for several months at 32°F and 90 to 95 percent relative humidity. If the temperature is allowed to rise, sprouting will occur. If the relative humidity is too low, the roots will desiccate.

See Cornell Report: Food Safety Begins on the Farm

See Cornell "Smart Marketing" series.

See USDA grade standards for bunched carrots, topped carrots, short trimmed topped carrots, and processed carrots

See USDA Marketing site

See See current wholesale prices from US markets

See UC Davis post harvest guide for carrots

SARE Publication: "Marketing Strategies for Farmers and Ranchers"

SARE Publication: "Direct Marketing Resource Guide"

Disease Management

| Aster yellows | Cavity spot | Rhizoctonia crown rot |
| Alternaria leaf blight | Northern root_knot nematode |
| Sclerotinia white mold | Seed decay | Storage rots |

SARE Publication: "A Whole-Farm Approach to Managing Pests"

Ontario Canada fact sheet on carrot root diseases

Time for concern: Planting through end of the season
Key characteristics: Elliptical- to irregular-shaped depressed lesions appear across the tap roots. Initially lesions are usually less than 1 1/2 inches in diameter at different stages of decay. Symptoms may not be apparent until carrots are approaching marketable size.

Management Option	Recommendation
Scouting/thresholds	Record the occurrence and severity of cavity spot. No thresholds have been established.
Resistant varieties	Carrot varieties differ widely in their susceptibility to cavity spot, but varieties reported to perform better include Six Pak, Six Pak II, 24 Karat, and Dagger 78. Table of carrot disease resistant varieties
Crop rotation	Minimum three year rotation out of vegetables and alfalfa. Crop rotation and disease management article Cornell cover crop decision tool Cornell Forage Species Selection Tool
Site selection	Select fields with well drained , light textured, and healthy soils. SARE Publication: "Building Soils for Better Crops" SARE publication: "Managing Cover Crops Profitably"
Seed selection/treatment	Plant vigorous, disease-free seed that has been treated with fungicides (Apron and Maxim).
Harvest	Harvest carrots soon after they reach maturity because older carrots are more susceptible to this disease.
Postharvest and Sanitation	These are not currently viable management options.

Compound(s)
Comparing Environmental Risks of Pesticides In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
Common name Trade Name	Rate/A Product	PHI (days)	REI (hours)	Field Use EIQ	Comments
mefanoxam
Ridomil Gold EC	1-2 pt	-	12	14-28	Rates are for PPI or surface application.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Key characteristics: Crater rot - symptoms result from infections of R. solani on the main root, often where lateral roots emerge. Under favorable conditions, lesions of initial infections continue to enlarge and develop into brown to black sunken cankers. The canker/rotted areas remain dry unless colonized and softened by other soil organisms. The lesions may penetrate several millimeters into the tap root; this distinguishes crown rot from the cavity spot lesions caused by Pythium species which are much shallower. Foliar blight - symptoms first appear on tissues of the petioles or the crown areas. A thin, brown layer of mycelial growth (hymenial layer) becomes visible on the surface of petioles or crown areas. Small spores are produced on these layers and may be carried away by splashing rain or winds and infect adjoining plants. Typical cankers may also appear on the infected areas, and severely infected plants may die resulting in open spaces.

Management Option	Recommendation
Scouting/thresholds	Record the occurrence and severity of crown and foliar blight diseases. No thresholds have been established.
Resistant varieties	No resistant varieties are available.
Crop rotation	Rotate out of vegetables, preferably with grain crops.Crop rotation and disease management article Cornell cover crop decision tool Cornell Forage Species Selection Tool
Plant density	Heavy plant density and narrow row spacing of carrots will increase the severity of these diseases, especially under moist conditions.
Hilling	Excessive hilling of carrots, under moist conditions, will increase disease occurrence.
Fungicide use	Applications with thorough coverage of the lower petiole and crown area effectively control foliar blight disease, if applied before infections occur (prior to hilling).
Seed selection/treatment	Plant vigorous, disease-free seed that have been treated with fungicides.
Postharvest	If possible, plow crop debris immediately after harvest to remove this source of inoculum for other plantings and to initiate decomposition.
Site selection	Select well drained sites with light textured and healthy soils. Planting on raised ridges will also be helpful. SARE Publication: "Building Soils for Better Crops" SARE publication: "Managing Cover Crops Profitably"
Sanitation	These are not currently viable management options.
Compound(s)	Quadris, Amistar, Rovral, and Cabrio are effective agaiinst Rhizoctonia

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Insect Management

| Aphids | Aster leafhopper | Carrot Rust Fly |
| Carrot Weevil |

SARE Publication: "Manage Insects on Your Farm: A Guide to Ecological Strategies"

SARE Publication: "A Whole-Farm Approach to Managing Pests"

Time for concern: June through harvest

Key characteristics: Adults vary in color. Aphids are generally about 1/16 inch long. Aphid infestations usually occur on new growth causing yellowing or wilting of foliage.