Carrot production
Land preparation
Proper land preparation should begin by deep turning soils to bury any litter and debris and breaking soils to a depth of 12-14 inches. Compacted soils or those with tillage pans can benefit from subsoiling to break the compacted areas. If uncorrected, compact soil or tillage pans can result in restriction of root expansion. It is best to apply lime after deep turning to prevent turning up acid soil after lime application. After turning, mark beds using tractor tracks. Prepare a good seedbed using bed-shaping equipment. Do not use disks or rototiller to avoid soil compaction. Carrots in Georgia should be planted on a slightly raised bed (2-3 inches) to improve drainage. After beds are tilled and prepared for seeding, it is best to allow the beds to settle slightly before planting. Avoid other tillage practices that can increase soil compaction. http://extension.uga.edu/publications/detail.html?number=B1175 Carrots like consistency: They grow best with no wide swings in temperature or moisture. They grow straightest and smoothest in deep, loose, fertile sandy loams and peat soils, with good water-retention capacity to keep moisture levels even. To the extent a grower can influence the environment, these favourable conditions are most effectively achieved through correct bed preparation and spacing, and timely weeding and watering. Carrots prefer well-drained, deeply-worked soil: preferably to an 18″ depth for the longer varieties, though a shallower depth may suffice for shorter varieties. Heavier soils are okay for half-long or round types.
Deeply-worked soil minimizes the resistance encountered by the growing carrot roots as they elongate. Resistance can lead to misshapen roots. While interesting to look at, forked, stunted, or twisted carrots are more prone to damage during harvest; are less easily handled, transported, and stored post-harvest; and generally don’t sell as well as smooth, evenly proportioned carrots. http://www.johnnyseeds.com/growers-library/vegetables/carrot-bed-preparation-spacing-weeding-watering.html
Soil requirements
Muck soils or loose, friable sandy loam soils are ideal for carrot production. Although heavier soils are not ideal, carrots can successfully be grown on heavy-textured soils under irrigated conditions. Short, blunt types are often grown on heavier soils. Sandy loam soils allow proper growth and development of a long, smooth, straight root. Soils cannot have excessive stones, pebbles and debris since this can cause forked or misshapen roots. Soils should also be well drained as carrots will not perform well under water-logged conditions. Sites should be selected that have loose, friable soils to a depth of 12-14 inches without pebbles. Deep sandy soils can also be used although they may require more frequent irrigation. Drain tiles should be installed on flatwood type soils that are subject to water-logged conditions. Preparing high beds to avoid wet conditions in these soils is not recommended since under drier circumstances these beds will dry out and cause damage to carrot tops and shoulders. http://extension.uga.edu/publications/detail.html?number=B1175#Soil and Nutrition
Variety
- Nantes varieties are 6 to 7 inches long, cylindrical (not tapered), and entirely edible. They are medium-sized, sweet and mild, and have a crisp texture.
- Danvers carrots are a classic heirloom carrot 6–8” long that tapers at the end, with a rich, dark orange color. This variety can handle heavy soil better than most varieties.
- ‘Little Finger’ is a small Nantes type of carrot only 4 inches long and one inch thick. Great for containers.
- ‘Bolero’: resists most leaf pests.
- ‘Thumberline’: round carrot, good for clumpy or clay soil
https://www.almanac.com/plant/carrots
Planting
Before sowing carrot seed, make sure your garden bed is thoroughly weeded, because carrots give up easily when confronted by tougher plants. Carrot seed is a very fine, small seed, which is difficult to sow in proper rows and with proper spacing. There are however, seeds that are sold attached to tape or pelleted, making it easier to sow in an evenly spaced fashion. (Pelleted seed is seed surrounded by inert materials which dissolve after planting. It’s easier to see when sowing.). If you’re not concerned with an orderly carrot bed, you can also broadcast the seed across the bed and thin the seedlings later.
Plant carrot seed 1/2″ deep, and attempt to space the seeds evenly, according to packet directions for your variety – generally speaking, maturing carrots should be about 2.5 – 3 inches apart. Gently tamp down the seed bed with your hands after sowing, so the seeds make contact with the soil. Water in lightly. If you love carrots and are planting a boatload, I highly recommend that you stagger your plantings 2 weeks apart so they don’t all mature at once. http://www.bigblogofgardening.com/how-to-grow-carrots-soil-prep-planting-harvesting/
- Plan to plant seeds outdoors 3 to 5 weeks before the last spring frost date.
- Carrots are ideally grown in full sunlight, but can tolerate a moderate amount of shade.
- Make sure your soil is free of stones; carrots need deeply tilled soil that they can push through.
- Fresh manure, or even recently applied rotted manure, can cause carrots to fork and send out little side roots. Don’t use it before you plant your seeds.
Plant Spacing
- Allow for at least 12″ between rows; 18″ is ideal.
- Spacing also depends upon the variety grown and its top height. Smaller-rooted or smaller-top varieties, such as Atlas(Parisian Market type), Caracas, or Adelaide, can be packed in a little more closely than some of the larger Nantes and Imperator types.
- Spacing needs are also dictated by the width of the cultivation equipment being used.
- Consider planting pelleted seeds with a precision seeder to achieve neat, accurately spaced carrot rows and minimize labor and waste. https://www.almanac.com/plant/carrots
Pest and diseases Management
In order to produce high yields of high quality carrots disease management is very necessary. The major concern is the production of a disease-free and cosmetically clean carrot root. The main problems associated with carrot production are root-knot nematodes and diseases caused by fungi and bacteria. Carrots should be planted in well-drained, litter-free, deep turned soils. Certain crops like tobacco should be avoided because of the slow decomposition of the crop stubble. Also, nematode control in tobacco stubble is difficult to achieve because nematodes can withstand treatment as they are embedded in the root system and may not be exposed to the fumigant. Several root diseases will be discussed in this section.
Also, certain foliage diseases can affect carrots. In most cases, these never require any type of fungicide or bactericide application. However, under certain weather conditions, fungicide applications may be necessary. Basically, adequate fungicides and bactericides for managing the above ground diseases are available.
Root Knot Nematode
By far, the most destructive problem is root-knot nematodes caused by Meloidogne sp. Root-knot nematodes are small eel-like worms that live in the soil and feed on plant roots. Since the root of the carrot is the harvested portion of the plant, no root-knot damage can be allowed. Root-knot causes poor growth and distorted or deformed root systems, which results in a non-marketable root. Root-knot damage also allows entry for other diseases such as Fusarium, Pythium, and Erwinia. Soil assay is the best way to determine the numbers and kinds of nematodes to be dealt with in carrot production. A nematode assay should be made during the months of July, August, or September, depending on the current crop. Nematode populations are usually at a peak at about crop maturity. Thus, the most accurate numbers can be obtained during this period. If any root-knot nematodes are found, treatment is recommended. Good success has been obtained using field soil fumigation to eradicate root-knot nematodes in the root zone of carrots.
Soil borne disease
Depending on the cropping history of the field, Pythium, Southern Blight and Sclerotinia may cause problems. It is advisable to avoid fields where these diseases have been identified in the previous crop. Deep turning is also necessary to help prevent root diseases.
Pythium blight
This is usually characterized by flagging foliage indicating some root damage is occurring. Under wet conditions, Pythium may cause serious problems to the root causing a white mycelium mat to grow on the infected area that rapidly turns to a watery soft rot. Forking of the root system is also a common symptom associated with Pythium infection.
Foliar disease
Bacterial Blight
Bacterial Blight caused by the bacterium Xanthomonas carotae causes irregular brown spots on the leaves and dark brown streaks on the petioles and stems. The lesions on the foliage begin as small yellow areas with the centers becoming dry and brittle, with an irregular halo. The bacterium affects the leaflets, stems and petioles as the disease progresses. Some of these lesions may crack open and ooze the bacteria. These bacteria may be washed down to the crown of the plant causing brown lesions on the top of the root. The earlier the infection the more damage to the root. The bacterium is spread by splashing water and takes about 10-12 days before symptoms appear after inoculation. The bacterium progresses rapidly between 77 degrees and 86 degrees F. Rotation is a major factor in controlling Bacterial Blight
Soil insects
Wireworms, mostly Conoderus spp., white grubs, Phyllophagus spp., and the granulate cutworm, Feltia subterranea, may be partially controlled with good cultural practices. Soil should be deep turned in sufficient time prior to planting to allow destruction of previous crop residue that may harbor soil insects. When possible, avoid planting just after crops slow to decompose, such as tobacco and corn. Avoid planting behind peanuts and root crops such as sweet potatoes and turnips. If a field has a history of soil insect problems, either avoid these or broadcast incorporate a soil insecticide prior to planting. Plantings in fields recently in permanent pasture should be avoided as should fields recently planted to sod/turf, although these are not as critical. Fields with a history of whitefringed beetle larvae, Graphognathusspp., should not be planted to carrots because there are no currently registered insecticides effective on this pest.
Weed control
Weed control in carrots is an essential component of producing a high-yielding and high-quality crop. Weeds compete with carrots for light, water, nutrients, and physical space. In addition, many weeds may impair the harvesting process, either through improper digging or contamination of the harvested crop. Weeds can also harbor deleterious insects and diseases. The presence of plant residue from weeds or other plants during fumigation can also decrease the effectiveness of most soil fumigation materials, thus increasing the problems associated with nematodes.
Most of the fumigants used in carrots grown in Georgia will not provide adequate weed control, therefore additional weed control measures must be employed. Carrot growers face a multitude of weed problems including both summer and winter annual broadleaf weeds and grasses.
These may include sicklepod (Cassia obtusifolia), crabgrass (Digitaria spp.), pigweeds (Amaranths spp.), carpetweed (Mollugo verticillata), lambsquarters (Chenopodium album), wild radish (Raphanus raphinistrum), cut-leaf evening primrose (Oenthera lanceolata), and several others.
Prevention is the first step in managing weeds in carrots. Avoid areas that contain heavy infestations of perennial weeds such as Bermuda grass and nutsedge. Proper tillage, insect and disease control and fertility will help to ensure a healthy crop. Planting density will also allow the carrots to out-compete many weeds. Mechanical cultivation is generally not used in carrot production due to the tight row spacing (several rows on a bed). However, mechanical cultivations will help control weeds between rows particularly during early fall planting.
One of the worst weeds in carrots, as in most crops, is nutsedge. Most infestations are limited to yellow nutsedge (Cyperus esculentus), which is found throughout Georgia. Linuron and metribuzin may provide some temporary suppression, while trifluralin and fluazifop have no effect. Nutsedge causes the greatest problem in the early fall, during carrot emergence and seedling growth. This limits the use of higher rates of linuron for some suppression due to the small carrot size. Unfortunately, the lower rates give no control. The stale-seedbed technique may provide some control and can be effectively used in carrots for nutsedge because nutsedge will emerge several days before the carrots. A non-selective material such as Roundup Ultra or Gramoxone Extra is commonly used. As with most weed management strategies, proper weed identification, site selection and timing are the critical issues in controlling weeds in carrots.
Harvesting
Mechanical harvesting can wound produce, encouraging contamination from the soil. Hand harvesting may lead to pathogen contamination if field workers practice poor hygiene. Field crews must be trained and monitored for personal hygiene (hand washing activities), and portable bathroom and hand-washing facilities must be provided in the field. Containers for harvesting fresh produce should be non-toxic, easy to clean and free of extraneous materials (e.g., nails, wood splinters, etc.) that can carry over into processing. They must be approved by the U.S. Department of Agriculture (USDA) or the Food and Drug Administration (FDA) for field use. After detergent cleaning, field bins, buckets, etc., can be sanitized using a very strong sodium hypochlorite solution dispensed from a high-pressure sprayer.
Post-harvest handling
Harvesting and packaging
Machine harvested carrots are loosened under the row by pull-like devices and elevated out of the soil onto belts that grasp the carrot tops. These tops are cut mechanically and allowed to fall back into the field while the trimmed roots are elevated to trucks for bulk transport to the packing house. At the packing house, carrots are off loaded into a dry dump tank, conveyed through a cylindrical revolving cleaner to remove dirt and sand, and then they enter a revolving drum washer with spray nozzles. Washed carrots then proceed through a series of sizing belts, where they are sorted by length and diameter. Diverging rollers are used to separate roots for diameter, and an inclined, vibrating platform with graduated hole sizes separates roots according to length. Sized carrots drop onto conveyor belts for hand grading to remove culls and are then hand packed into one-, two-, three- and five-pound polyethylene bags, which are subsequently palletized into 50 pound, heavy polyethylene master bags.
Mechanical damage to the roots can be minimized by the proper operation of all harvesting, sizing and grading equipment. Excessive speed or overloading of equipment will result in an increase of mechanical damage to the carrots. Such bruising or cutting will open up avenues for greater water loss and invasion of decay microorganisms.
Precooling and storage requirements
Carrots have a high rate of respiration, which means field heat must be removed before dense packaging and storage. Precooling is accomplished by using cold water in the revolving drum washer or running field bins through a hydro cooler. Keep temperatures at 40 degrees F.
Topped fresh market carrots are very perishable and rapidly transpire moisture from even trimmed roots. Wilting symptoms become evident with as little as a 3 percent weight loss. Therefore, high humidity (95-100%) is imperative in storage. Free moisture, if allowed to condense on carrots will promote decay. Good air movement is necessary to prevent decay during storage. Topped carrots should be held at 32 degrees F. If the above conditions are met, the shelf life of immature, topped carrots is four to six weeks.
Storage compatibility
Carrots have the same storage requirements as beets, broccoli, brussels sprouts, cabbage, cauliflower, celery, collards, sweet corn, endive, greens, lettuce, green onions, parsley, parsnips, peas, radishes, snow peas, spinach, and watercress. Therefore, these crops can be stored together without deleterious effects. However, carrots should not be stored with ethylene producing crops (e.g., cantaloupes, apples, etc.). Carrots are sensitive to as little as 0.5 ppm ethylene. This will impart a perceptible bitter flavor to the carrots.
Post-harvest Decay
Postharvest decay organisms are obligate parasites and therefore, do not normally enter the product through healthy, exterior tissue. These organisms require mechanical damage or weakening of tissue before they can enter. Spoilage losses can be minimized if the following precautions are observed: Use new or disinfected storage containers, handle carrots carefully to prevent injuries, precool roots properly, and maintain carrots at a constant temperature slightly above 32o F.
The most important decays of carrots in storage are gray mold rot (Botrytis), watery soft rot (Sclerotinia), crater rot (Rhizoctonia), fusarium rot, rhizopus soft rot, bacterial soft rot, black rot (Stemphylium), and sour rot (Geotrichuim).
http://extension.uga.edu/publications/detail.html?number=B1175#Disease Management
Market structure
There is no regulation or restriction in the marketing of carrots. The prices of carrots are determined by market forces of demand and supply. The industry uses local market, informal market, processor and direct selling to wholesalers and retailers. Carrots are also exported to other countries through export agents and marketing companies. South Africa also imports carrots from other countries. http://www.nda.agric.za/docs/AMCP/CarrotVCP2009-2010.pdf
