The University of Georgia College of Agricultural & Environmental Sciences
Cooperative Extension Service

Commercial Eggplant Production

Darbie M. Granberry - Extension Horticulturist

Contents

Variety Selection
Soil and Land Preparation
Fertilizer Requirements
Transplanting
Irrigation
Pollination
Diseases
Environmental Stress
Insect Pests
Weed Control
Postharvest Handling

Most commercial eggplant production in Georgia occurs in the southern part of the state; however, eggplant is grown in gardens throughout Georgia.

The eggplant (Solanum melongena) is a native of the tropics. The name eggplant was probably derived from the plant type that produces small white fruit resembling the chicken egg. This type has become popular in recent years as a novelty item.

Eggplant is an annual in temperate zones and perennial in the tropics. In Georgia, plant height averages 3-1/2 to 4-1/2 feet for most cultivars. Fruit shape ranges from oval to elongated oval and averages approximately six by five inches for traditional cultivars such as Black Beauty. Oriental cultivars bear fruit that tends to be long and slender (six to 12 inches in length and 1-1/2 to two inches in diameter). Most cultivars have purple to blackish-purple skin, but some are white, green or mottled green with white flesh.

Since it is a warm-season crop, eggplant requires continuous warm weather during growth and fruit maturation. Day temperatures of 80 degrees F are considered optimum. Growth stops at temperatures below 60 degrees F, so for the best growth, night temperatures should exceed 60 degrees F. The eggplant is more susceptible to injury by low temperature than are tomatoes or peppers.

Variety Selection

Many eggplant cultivars are readily available from major seed companies. Cultivars differ in earliness, as well as in size, shape and color of mature fruit. A primary consideration in cultivar selection is market preference. Individual markets usually prefer or require a specific type(s) of eggplant. Ideally, a potential grower should identify the prospective market (buyer, broker, packer), then determine (1) if that market perceives a need (demand) for the product, (2) the production volume (bushels per acre) which the market could use, (3) the specific varietal characteristics desired or required by the market, and (4) the market window or duration of time during which that market anticipates a demand for eggplant. The grower should then determine cultivars, planting dates and acreage based on perceived market needs, varietal attributes and average climatic conditions for specific areas of production.

A number of Georgia growers continue to engage in "speculative" production of eggplant (as well as other vegetables). Such production is characterized by a casual selection of a vegetable and/or a variety, acreage, and production season. The grower then speculates that an acceptable market will be found by harvest time. This type of production is not recommended.

Most commercial eggplant cultivars should produce 500 to 700 bushels of marketable product per acre. To obtain the highest yields, eggplant should be harvested at least five or six times at seven- to ten- day intervals.

Many of the eggplant cultivars currently available are F1 hybrids. Hybrid seeds are much more expensive than open-pollinated seeds, but tend to grow more uniformly and produce higher marketable yields. Although seed counts may vary with cultivar, one ounce of eggplant seed contains approximately 6,000 seeds.

 

Eggplant Cultivars
Cultivar Days /1 Type /2 Plant Height Fruit Color Fruit Shape
Beauty 65-67 F1 25 inches Glossy black Oval
Black Beauty 77-79 O.P. 24-30 inches Nearly black Oval
Black Bell 68-72 F1 28 inches Glossy, deep purple black Round/oval
Black Jack 66-70 F1 32 inches Medium dark Oval
Dusky 61-64 F1 24 inches Glossy black Oval
Epic 63-65 F1 36 inches Deep purple-black Oval
Fla. Mkt. 10 84-86 O.P. 36-48 inches Glossy, very black Tapered cylinder
Ichiban 57-59 F1 32 inches Soft, dark purple Slender cylindrical

/1 Expected no. of days from transplanting to maturity when grown under favorable conditions (data provided by respective seed companies).

/2 Type: F1 = hybrid, O.P. = open pollinated

Note: Varietal performance may be influenced by cultural practices and environmental conditions. Please check with the appropriate seed companies for detailed varietal descriptions and characteristics. Cultivars in this table are not inclusive of all cultivars grown in Georgia nor is this listing intended to be an endorsement to the exclusion of other cultivars which may be similar.

 

Soil and Land Preparation

Well-drained, sandy loam soils are ideal for eggplant production. Poorly drained soils usually result in reduced functional root area, poor plant growth and low yields.

Site selection can be important if early eggplant production is required. For early production, select sites with a southern to southwestern exposure. Soil with a southern exposure receives more sunlight in the spring and therefore warms more quickly.

Plan crop rotation so that eggplant is not planted after eggplant or other solanaceous crops such as tomato or pepper.

Good soil preparation is important for optimum eggplant production. If large amounts of plant debris are present, disk land several weeks before transplanting, then plow land using a moldboard plow. This will loosen the soil and bury old crop residues. Turn soils at least eight inches deep.

Adequate soil preparation facilitates the growth and development of an extensive root system. Plants will then have a larger volume of soil from which to draw water and nutrients, reducing the chance of moisture and nutrient stress. Discing soil after turning can cause recompaction. If planting beds need to be made or smoothed prior to transplanting, use a rotary tiller or similar implement and maintain the same wheel patterns throughout subsequent operations.

Eggplant is intolerant of poorly drained soil, so it is usually helpful (especially on heavier soils or in low areas) to transplant eggplant on raised beds.

Fertilizer Requirements

Base fertilizer and lime applications on soil tests. Soil pH should be maintained at 6.0 to 6.5. If magnesium deficiencies were observed on previous crops, or if the soil test indicates a low magnesium level, dolomitic lime should be used if lime applications are made. Dolomitic lime is six to 12 percent magnesium. Lime application is most effective if it is broadcast and incorporated into the soil three to four months before eggplant is seeded or transplanted.

Phosphorus and Potassium Recommendations

The following chart indicates the pounds of fertilizer nutrients (P2O5 and K2O) recommended for soil fertility levels according to soil test ratings of residual phosphorus (P) and potassium (K).

Apply the recommended phosphorus during or near transplanting. Apply approximately pint of a starter solution of three pounds of 10-34-0 (or similar material) mixed in 50 gallons of water to each transplant. In addition, application of 100-150 pounds of a pop-up fertilizer such as 10-34-0 two to three inches to the side and below the roots promotes earlier growth, particularly in the early spring.

 

Phosphorus (P) Rating Potassium (K) Rating
Low Medium High Very High
P2O5 K2O P2O5 K2O P2O5 K2O P2O5 K2O
Low 120 120* 120 90 120 60 120 30
Medium 80 120 80 90 80 60 80 30
High 40 120 40 90 40 60 40 30
Very High 0 120 0 90 0 60 0 30

* pounds per acre

 

From to of the potassium should be applied in two bands, two to three inches to the side and two to three inches below plant roots or be incorporated in the bed prior to transplanting. Research shows that bed incorporation can be less effective than banding. The remainder of the recommended potassium should be applied in one to three applications, as needed.

Nitrogen Recommendations

Typical Coastal Plain soils require 100 to 150 pounds of nitrogen (N) per acre. Extremely sandy soils may need additional nitrogen or an increased number of applications. Piedmont, Mountain and Limestone Valley soils usually require 100 to 120 pounds of nitrogen for optimum production.

Necessary nitrogen rates will vary by season, depending on rainfall, soil type, irrigation, plant population, duration of the harvest season and method and timing of applications.

For typical Coastal Plain soils, to of the recommended nitrogen should be applied in two bands, two to three inches to the side and two to three inches below plant roots or incorporated in the bed prior to transplanting. Research shows that bed incorporation can be less effective than banding. Sidedress with 20 to 30 pounds of the recommended nitrogen when the first fruits are the size of a hen's egg. Apply the remaining recommended nitrogen in one to three applications as needed. For heavier Piedmont, Mountain and Limestone Valley soils, less nitrogen in fewer applications is usually required.

Magnesium, Sulfur, Zinc and Boron Recommendations

If the soil test indicates low levels of magnesium and lime is recommended, apply dolomitic limestone. If magnesium levels are low and lime is not recommended, apply 25 pounds of elemental magnesium per acre. Apply a minimum of 10 pounds of sulfur per acre, one pound of actual boron per acre, and if soil tests indicate low levels of zinc, apply five pounds of actual zinc per acre.

Transplanting

Although eggplant may be seeded directly in the field, this is not usually recommended. Direct seeding has several possible disadvantages: In most areas, eggplant is transplanted in the field to provide the best opportunity for growth and fruit development under optimum temperatures. Transplanting usually results in more efficient land use and provides the best means of establishing a uniform and complete stand. As with most vegetable crops, field grown (bare-root) or container grown transplants may be used. Container grown transplants retain transplant growing media on their roots after the plants are removed from the container. Many growers prefer this type of transplant because the plants are less subject to transplant shock, they usually require little, if any, replanting, they resume growth more quickly after transplanting and they grow and produce more uniformly.

Harden off eggplant transplants before transplanting in the field. Hardening off is a technique used to slow plant growth prior to field setting so the plant can withstand unfavorable conditions in the field more successfully. Any treatment that restricts growth will increase hardiness.

For maximum production, transplants should not have fruits, flowers or flower buds before transplanting. An ideal transplant is young (eight to 12 inches tall), does not exhibit rapid vegetative growth, is slightly hardened at transplanting time and should not be overhardened or too soft when transplanted. Transplants held too long before transplanting will be too old and woody and are slow to resume growth after transplanting. Rapid growth following transplanting helps assure a well-established plant before fruit development.

Plants should be set two to 2-1/2 feet apart in rows three to four feet apart. The optimal population depends upon the vigor of the cultivar, climate, moisture sufficiency, soil productivity, and intensity of management, but is approximately 4,000 to 6,000 plants per acre.

Each transplant should be watered in with approximately pint of a starter solution consisting of three pounds of 10-34-0 (or similar material) mixed in 50 gallons of water. This provides nitrogen and phosphorus to enhance rapid plant establishment and helps to eliminate air pockets by settling the soil around plant roots, but is no substitute for adequate rainfall or irrigation immediately after transplanting.

Irrigation

During deficient water conditions, eggplant responds well to irrigation. In the absence of sufficient rainfall, irrigation can be very beneficial from transplanting until the plants are well established. When the plants are established, maintain enough available moisture to keep plants actively growing.

Pollination

Research indicates that eggplant is not self-fruitful and not wind-pollinated; therefore, insect pollination is required for good yields. If feral (wild) bee activity is inadequate, beehives should be placed in or near the field. Depending on conditions and the native population of wild bees, one hive for one to three acres is adequate.

Diseases

Eggplant is susceptible to a number of diseases capable of causing serious losses. Most diseases can be prevented if precautions are taken early. Basic cultural practices help provide good disease control, but sometimes chemical control is also necessary.

Root-knot nematodes cause major damage to eggplant. Rotate plants to fields free of root-knot or use chemical control to prevent losses. Recommendations are found in the Georgia Pest Control Handbook.

Southern stem blight is the second most common problem. This is a soil-borne disease common to many crops. Rotation, litter destruction and deep turning are the best defenses against Southern stem blight.

Phomopsis blight is another disease affecting eggplant. This is primarily a fruit disease and is controlled by chemical sprays. The degree of control depends upon early diagnosis and weather conditions. Chemical control recommendations are found in the Georgia Pest Control Handbook.

Environmental Stress

Stressful growing conditions are caused by insufficient moisture, excessive moisture, insufficient availability of plant nutrients, or adverse temperatures. Stress results in poor plant growth and reduced yields of eggplant. Fasciation, caused by stressful growing conditions, is characterized by flattened eggplant fruit, which is unmarketable. For optimal yields and quality, prevent or alleviate stressful conditions as much as possible.

Insect Pests

Eggplant may be severely damaged by several insect pests. Most pests are sporadic and scouting is the most cost-effective means of determining the need for insecticide applications. Insects that commonly attack eggplant are stink bugs, leaf-footed bugs, tarnished plant bugs, thrips, corn earworms, flea beetles and spider mites.

Refer to "Commercial Vegetable Insect Control" in the Georgia Pest Control Handbook for a listing of insecticides.

Weed Control

Weed control is one of the most serious concerns to commercial eggplant growers. Because it is a serious problem in transplant seed beds and in the field, it is important that a cost-effective weed control program be put in place before establishing a plant bed or planting transplants in the field.

Factors Affecting Weed Control

From the standpoint of weed control, there are several factors to consider before venturing into eggplant production. For eggplant grown in seedbeds for transplants, the approach to weed control is different from that of eggplant grown in the field. For the production of transplants from seedbeds, select a sterilized soil mixture or use a land area that does not have a history of troublesome weeds or weeds that will be resistant to chemical control methods. For the production of eggplant transplanted to the field, select the best land possible in terms of weed history and crop rotation. This land should not have a history of troublesome weeds, especially weeds that germinate in mid- to late growing season. Examples of these weeds are sicklepod, yellow and purple nutsedge, Florida beggarweed, jimson weed, cocklebur and morning glories. Avoid land with an infestation of perennial weeds such as bermudagrass and johnsongrass. Weed identification is important because the total weed control strategy will depend on the weed species present and the degree of weed infestation. If possible, draw a weed map showing areas infested with different weed species in order to plan more effective control strategies.

Crop rotation is also important to maintain land free from troublesome weeds. During rotation, avoid land treated with herbicides to which eggplant may be sensitive. Many herbicides used for weed control in agronomic crops (peanuts, soybeans, corn, cotton and grain sorghum) have not been thoroughly tested for eggplant sensitivity. The residual soil life, particularly of the newer compounds, has not been fully established. Keep a record of the herbicides used on fields where eggplant will be planted and check the herbicide labels for crop rotation guidelines. The following table lists herbicides that can potentially cause severe injury or stand reduction in eggplant if sufficient rotation time is not allowed.

 

Herbicides that May Cause Severe Eggplant Injury or Stand Reduction through Carry-over
Herbicide Waiting Period*
Atrazine one year
Lexone/Sencor six months
Bladex one year
Milogard one year
Princep one year
Surflan six months**
Cotoran/Lanex two years
Karmex/Direx one year to 18 months
Lorox/Linex six months
Classic one year (possibly more)
Scepter one year (possibly more)

* Rotational time after application required to prevent injury to eggplant.

** Buildup of surflan with continuous yearly usage may result in injury even after a six-month waiting period.

 

Methods of Weed Control

In Seedbed

To avoid a weed problem in eggplant seedbeds, select a weed-free soil mixture or a land area without a history of a severe weed problem. Once selection is made, two approaches may be taken for further control of weeds in a seedbed:

Fumigation. The seedbed is tightly covered with an airtight tarp or plastic. A registered fumigant is injected under the cover and the seedbed is left undisturbed for three days. The cover is then removed and the soil is allowed to aerate for seven days before planting eggplant seeds. A properly applied fumigant penetrates the soil and kills most existing viable seeds. In general, registered fumigants are restricted use chemicals and must be handled carefully by a certified applicator. Apply all fumigants in full compliance with label recommendations and precautions.

Herbicides. Certain herbicides may be used (with or without fumigation) for weed control in seedbeds (See Extension Circular 695, Chemical Weed Control in Vegetables). Contact herbicides may be used in the "Stale seedbed" method, which allows the application of a contact non-residual herbicide before or after planting eggplant seeds, but before emergence. This method allows weeds to germinate and be killed before crop emergence. Preemergence herbicides may be applied immediately after planting, but before crop and weeds emerge (See Extension Circular 695, Chemical Weed Control in Vegetables).

In Field

Hand weeding is the safest and least damaging to the crop; however, only growers with small acreage and abundant labor can depend on this approach. Shallow cultivation is usually helpful in controlling weeds. For chemical control methods, please refer to Extension Circular 695, Chemical Weed Control in Vegetables or the Georgia Pest Control Handbook. There are several other methods to control weeds in fields:

Mechanical. Mechanical control is very effective during early growth, but once plants get too large, mechanical cultivation is not practical. Tractor wheels and cultivators easily damage crops, and mechanical cultivation usually requires supplementary Hand weeding to remove weeds in the rows.

Herbicides. Herbicide control is limited to chemicals recommended by the University of Georgia Cooperative Extension Service (See Extension Circular 695, Chemical Weed Control in Vegetables).

Stale seedbed. Stale seedbed control is a chemical method used to destroy weeds that emerge before eggplant is transplanted. A contact herbicide is applied immediately prior to transplanting eggplant and kills weeds that have germinated during the 7- to 10- day period after a preplant incorporated herbicide was applied.

Fumigation. Fumigation for weed control is expensive and dangerous and must be handled by trained personnel. The soil is covered with a non-perforated material such as plastic or a tarp, and all edges are sealed with soil. The cover remains in place for three days after fumigation. The cover is then removed and the soil is allowed to aerate for seven days before the eggplant is transplanted.

Plastic mulch. The use of plastic mulch with trickle irrigation is rapidly expanding as a weed control method. Black plastic is the most effective plastic mulch because the color prevents the light penetration which is necessary for weed seed germination. The edges of the plastic mulch must be properly embedded in the soil to prevent wind disturbance. Areas between mulched beds should be treated only with a preemergence or postemergence herbicide registered for eggplant use, because the eggplant root system is capable of extending into the treated zone. Plastic mulches are not effective for nutsedge control.

Postharvest Handling

Harvest eggplant when it reaches a marketable size and before the seeds become dark and the flesh becomes spongy and bitter. When mature, eggplant should be cut from the stem with a sharp knife or clippers, leaving the calyx (cap end) attached to the fruit. Good quality eggplant is firm, heavy (in relation to size), and free of cuts and scars. As fruit matures, the flesh softens, so careful handling to avoid bruising is necessary during harvesting and distribution.

Eggplant is too delicate to be run across a grading line, so it is packed in the field for marketing. Before packing, eggplant fruits are sorted by size and culls are removed. They are washed, if needed, individually wrapped in tissue paper and carefully packed to prevent the stems from puncturing other fruits. Proper sizing achieves a specified count per carton and is important for marketing. Eggplant is packed in waxed, corrugated or wirebound cartons, depending on market preference.

Eggplant harvested in hot weather should be precooled to extend shelf life. Eggplant, when properly cooled to 50 degrees F, will have a shelf life of 7 to 10 days. During cold storage, relative humidity of 90 percent is necessary to prevent shriveling and loss of color quality.

For more detailed information on postharvest handling of eggplant, consult Extension Bulletin 971, Handling, Packing and Cooling Quality Vegetables.

Attention: Pesticide Precautions

  1. Observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
  2. Store all pesticides in original containers with labels intact and behind locked doors. Keep pesticides out of reach of children.
  3. Use pesticides at correct label dosage and intervals to avoid illegal residues or injury to plants and animals.
  4. Apply pesticides carefully to avoid drift or contamination of non-target areas.
  5. Surplus pesticides and containers should be disposed of in accordance with label instructions so contamination of water and other hazards will not result.
  6. Follow directions on the pesticide label regarding restrictions as required by State or Federal Laws and Regulations

Trade and brand names are used only for information. The Cooperative Extension Service, The University of Georgia College of Agricultural and Environmental Sciences does not guarantee or warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.

The pertinent contributions made by Dr. David Adams, Extension Entomologist; Dr. Fitzroy Bullock, Extension Agronomist; Dr. Johnny Dan Gay, Extension Plant Pathologist; Dr. William C. Hurst, Extension Food Scientist; and Dr. Charles Vavrina, Extension Horticulturist, are gratefully acknowledged.

Circular 812/January, 1990

The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.

An Equal Opportunity Employer/Affirmative Action Organization Committed to a Diverse Work Force

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.

Gale A. Buchanan, Dean and Director

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