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Chapter 16: Carrots

16.1 Varieties

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. Varieties that have done well in trials include Bolero, Magnum, Red core Chantenay, Ya Ya and Danvers. Cultivars vary in susceptibility to aster yellows.

16.2 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 16.2.1 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

Do Rotations Matter within Disease Management Programs?

16.3 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 16.3.1 for the recommended rates of nitrogen, phosphorus, and potassium.

Table 16.3.1 Recommended nutrients based on soil tests

N pounds/acre P2O5 pounds/acre Soil Phosphorus Level   K2O pounds/acre Soil Potassium Level 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.

16.4 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.

16.5 Disease Management

16.5.1 Aster Yellows
16.5.2 Cavity Spot
16.5.3 Rhizoctonia Crown Rot and Foliar Blight
16.5.4 Alternaria Leaf Blight, Cercospora Leaf Blight, and Bacterial Leaf Blight
16.5.5 Northern Root Knot Nematode
16.5.6 Sclerotinia White Mold
16.5.7 Seed Decay, Damping-off, and Root Rot
16.5.8 Storage Rots

 

16.6 Insect Management

16.6.1 Aphids
16.6.2 Aster Leafhopper
16.6.3 Carrot Rust Fly
16.6.4 Carrot Weevil
16.6.5 Wireworms

 

16.7 Weed Management

 

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Maintained by Abby Seaman, New York State IPM Program. Last modified 2019.