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This publication is the result of a joint effort among the seven disciplines in the University of Georgia College of Agricultural and Environmental Sciences that serve the Georgia vegetable industry. The 11 topics covered in this bulletin are all integral parts of a successful cabbage/leafy greens management program. Each topic focuses on a particular aspect of production and provides information on the latest management technology for that phase of production. It is hoped that the information contained in this publication will assist growers in improving profitability. Chemical pest control recommendations are subject to change from year to year; thus, only general pest control guidelines are mentioned in this publication. Growers are urged to consult the current Georgia Pest Control Handbook or check with their local county Extension agent regarding the most recent chemical recommendations. Mention of tradenames in this publication is neither an endorsement of a particular product nor a lack of endorsement for similar products.

Cabbage and leafy greens, including turnip, mustard, kale and collard, have a long history of production in Georgia. The cabbage and leafy greens industry makes up almost 20 percent of the Georgia vegetable industry's acreage, with almost 30,000 acres under production in a given year. The nature of the industry has changed, however, with more emphasis on shipping and less on locally marketed product. The bulk of all these crops remains in the fresh market, with a growing segment of processed greens.

The botanical classifications of several types of cabbage and leafy greens grown in Georgia are listed in Table 1. Brassica oleracea includes all cabbage, collard and kale. This group has long been referred to collectively as "cole crops." This term comes from a Middle English or Norse word that originated from the Latin word caulis, which refers to the cabbage stem or stalk. Wild types of these crops have been found along the Atlantic Coast of Europe and cabbage, kale and collard are believed to have originated in Western Europe. Early uses of these crops were for medicinal purposes.

Table 1. Botanical classification of several types of cabbage and leafy greens

Kale is thought to be the first form to be domesticated and may have been cultivated as early as 2000 BC. Hard-headed types of cabbage were not cultivated until around the ninth century. Traders and explorers spread the crops to other parts of the world, where they were quickly adopted as cultivated crops. Although cabbage is not particularly high in protein, vitamins and minerals, kale is one of the most nutritious vegetables grown, based on fresh weight. Mustard originated in central and eastern Asia, the Mediterranean and the Himalayas.

Uses of cabbage and leafy greens vary widely. All are grown for both the fresh market and processing into any number of products. Cabbage is popular as a fresh item used in slaw, cooked or processed into preserved products such as sauerkraut. Kale is used primarily as a garnish because of its attractive curly leaves. However, kale can be cooked and eaten in much the same fashion as other leafy greens. Collard, turnip greens and mustard are used primarily as cooked fresh vegetables. However, the tendency to find them served in a raw form is increasing. All are grown for the fresh market but also are grown widely for processing both as canned and frozen products.

Collard, kale, turnip and cabbage are dicotyledonous herbaceous plants that are biennial in nature, although the wild form of cabbage is an annual. All are grown commercially as annuals, however. Kale, turnip and collard do not form a head; all have a rosette form of vegetative growth on a short stem. Collard produces a large smooth leaf, and turnip produces smaller leaves that are generally pubescent. Newer varieties of turnip may be smooth-leaved and are more similar in appearance to mustard. Mustard is a cool-season annual that also forms a rosette of vegetative growth. Mustard leaves may be curly or smooth depending on the cultivar. Cabbage forms a head as the leaves mature and become densely packed.

Cabbage and leafy greens are all produced for their leaves. Some types of turnip also produce a fleshy root harvested for consumption. These roots can vary in shape from flat-round to elongated to spherical. The outer color may be totally white or have shades of red or purple, particularly at the shoulder. Cabbage, collard and kale are hard to distinguish from one another at the seedling stage but soon develop recognizable characteristics.

All of these crops may be subject to bolting (premature appearance of a flower/seed stem). Flowering usually occurs after an extended period of exposure to low temperatures (below 50°F) followed by a period of warmer temperatures. Exposure to temperatures below 40°F or above 70°F after low temperature exposure causes rapid emergence of the seed stem. Losses to bolting in these crops occur almost every year, particularly in overwintered crops that are exposed to severe temperatures. The flowers of the crops are whitish or yellow and are pollinated by insects.

Climatic Requirements

Cabbage and leafy greens are adapted to a wide range of environmental conditions and are grown throughout Georgia. Although the southwestern portion of the state produces the most, several areas contribute significantly, including the southeast and the northeast. Cabbage, collard and kale can tolerate hard frosts, but severe freezes can be damaging. Turnip and mustard can tolerate fairly cold temperatures, but hard frosts can kill the crops or make them unmarketable. All can be grown on a wide range of soil types and are somewhat drought tolerant, although production without irrigation is not recommended.

Most production of cabbage and leafy greens occurs in the spring, fall and winter months, except in the northern reaches of the state where production occurs in spring and summer. Collard production in the summer in South Georgia is generally difficult because of increased disease and insect pressure. However, many producers choose to grow it throughout the year. Mustard and turnip can be grown practically throughout the year in Georgia, but cooler temperatures make winter production unlikely in North Georgia. Heat, disease and insect pressure in the summer reduce production in South Georgia.

Crop Establishment

Turnip and mustard are direct seeded. Kale, collard and cabbage can be either direct seeded or transplanted. Transplanting has some advantages over direct seeding but also involves an increased cost. When purchasing transplants, growers should always buy Georgia-certified plants from reputable growers.
Producers of containerized plants specialize in growing plants in greenhouses that are designed specifically for the production of transplants. To contract with a grower for transplants, specify the cell size desired, the variety to be planted and a specific delivery date of the plants.

Also, determine whether the plant grower or the greens grower is to furnish the seed. The cost to the grower for this type of transplant will vary depending on the volume ordered and the cell size of the tray. Growing containerized transplants is a highly skilled, intensive operation that is usually not economically feasible for the greens producer.

Although some greens are seeded directly in the field, several recommended practices should be considered. Direct seeding has several problem areas that must be addressed:

1. Weed control is usually somewhat more difficult with direct seeding.
   
2. Direct seeding requires well-made seedbeds and specialized planting equipment adequate to control depth of planting and in-row spacing. Precision seeders that maximize singulation should be considered, although several types of seeders will do an adequate job.
   
3. Because of the shallow planting depth required, the field must be nearly level to prevent seeds from being washed away or covered too deeply with water-transported soil.
   
4. Spring harvest dates will be at least four weeks later for direct-seeded greens. At soil temperatures of 59°, 68° and 77°F, cabbage seeds require 15, nine and six days, respectively, for emergence. Turnip will emerge at soil temperatures of 50°, 59°, 68° and 77°F in five, three, two and one day, respectively, from seeding.

Typically, four- to six-week old cabbage, kale or collard seedlings are transplanted into the field. As with most other vegetable crops, field grown (bare-root) or container-grown transplants may be used. Container-grown transplants retain transplant growing media attached to their roots after they are removed from the container (flat or tray). Many growers prefer this type of transplant because it:

1. is less subject to transplant shock,
2. usually requires little, if any, replanting,
3. resumes growth more quickly after transplanting, and
4. grows and produces more uniformly.

Cabbage, collard and kale, like other transplants, should be hardened off before they are transplanted in the field. Hardening off is a technique used to slow plant growth prior to field setting so the plant can more successfully withstand unfavorable conditions in the field.

Cabbage, collard and kale transplants are sensitive to environmental conditions. Any condition that results in a prolonged cessation or checking of vegetative growth during the early stages of plant development can trigger the onset of bolting. Bolting is the development of small, unmarketable heads or flower stalks while the plant is still immature. Flower stalks can form when plants are grown below 50°F in the bed and are exposed to periods of cool weather (35° to 50°F) after field setting. Lack of nitrogen or other nutrient stresses as well as competition from weeds, insects or diseases that slow vegetative growth can promote flowering. Transplants that are older and less vigorous are more likely to flower than young, fast-growing plants. Bare-rooted plants that have been exposed to drying or severe water stress immediately following transplanting are also more likely to flower.

Flowering (heading out) can be prevented by:

1. Maintaining a steady, moderate rate of growth in the plant bed.
2. Setting out young, healthy transplants that have not been stressed.
3. Using transplant water to initiate root growth and remove air pockets from the soil.
4. Setting out plants under favorable conditions for growth and irrigating to relieve moisture stress.
5. Maintaining good vegetative growth, particularly for the first few weeks after field setting.

Cabbage and collard transplants should never have flower buds at transplanting. An ideal transplant is young (4 inches tall with a stem approximately ¹/8 inch in diameter), exhibits rapid vegetative growth, and is slightly hardened at transplanting time. Hardening may be indicated in the greens by a slight purpling of the outer part of the leaves. Good growth following transplanting helps assure a well-established plant.

Transplants should be set out as soon as possible after they are removed from their containers or pulled. If greens transplants must be held for several days before transplanting them, keep them cool (around 55° to 65°F, if possible) and prevent the roots from drying out prior to transplanting. When setting out plants, the transplant should be planted deeply enough to completely cover the rootball (slightly deeper than they were grown).

At transplanting, an appropriate fertilizer starter solution should be applied (see the section on fertilizer starter solutions). After transplanting (especially within the first two weeks), it is very important that soil moisture be maintained so that plant roots can become well established.

Plant Spacing and Planting Dates

The optimal plant population per acre depends upon the plant's growth habit (compact, medium or spreading), size (small, medium or large) at maturity, vigor of specific cultivars, climate, soil moisture and nutrient availability, soil productivity and intended use. Table 2 gives planting dates and recommended seeding and planting information for collard, cabbage, kale, turnip and mustard.

Plant spacing for cabbage and kale is usually about 36 inches between rows and 9 to 12 inches in the row. Turnip may be spaced closely (four to six seeds per foot) if no roots are to be harvested or spread to wider in-row spacings (three to four seeds per foot) if grown for roots and tops. One popular arrangement is to grow four rows, each 14 inches apart, on a 6-foot bed. Mustard arrangements are similar to turnip grown for greens only.

Collard spacing will depend on the harvest method. If young collards are to be harvested similarly to turnip, they may be grown in rows 12 to 18 inches apart with plants 2 to 4 inches apart in the row. If they are to be cropped or cut as whole plants, they should be spaced in rows 36 inches apart with plants 12 to 18 inches apart. Kale can be grown in 30- to 36-inch rows or with three rows on a 6-foot bed with plants 9 to 12 inches apart. Cabbage grown for sauerkraut or slaw may be spaced further apart in the row.

Planting dates can vary widely. However, those crops that are planted between late October and mid-February in South Georgia can come under significant risk of freeze injury. Although successful collard and cabbage production can be achieved with winter plantings, turnip, mustard and kale are more subject to cold damage.

Table 2. Recommended planting dates and planting information for cabbage, collard, kale, turnip and mustard produced in Georgia

	Turnip	Mustard	Collard	Kale	Cabbage
Planting Dates
North Georgia	March-Aug.	March-Aug.	Feb.-July	March-Aug.	Feb.-July
South Georgia	Aug.-Oct. Feb.-April	Aug.-Oct. Feb.-April	Aug.-June	Aug.-Oct. Feb.-April	Aug.-March
Planting Information
Seed/Pound	240,000	240,000	144,000	144,000	144,000
Seed/Acre, Drilled	1-2 pounds	2-3 pounds	1-2 pounds	1-2 pounds	1 pounds
Seed/Acre, Precision	1 pound	1 pound	¼ pound	¼ pound	¼ pound
Seed/Acre, Container Transplants	NA	NA	2-3 ounces	2-3 ounces	2-3 ounces
Field Transplants	NA	NA	6-8 ounces	6-8 ounces	6-8 ounces
In-row Spacing	½"-6"	5"-10"	2"-18"	8"-12"	9"-12"
Between-row Spacing	12"-36"	12"-36"	12"-36"	18"-36"	30"-42"
Seeding Depth	1/8"-¼"	1/8"-¼"	¼"	¼"	1/8"-¼"
Seed to Harvest	35-50 days	35-50 days	60-90 days	60-80 days	90-140 days
Transplant to Harvest	NA	NA	6-10 weeks	6-8 weeks	70-120 days
Optimum Soil Temperature for Germination (°F)	60-85	60-85	50-85	50-85	50-85
Optimum Air Temperature for Crop Growth (°F)	60-65	60-65	60-65	60-65	60-65

Variety Selection

Numerous varieties of cabbage and leafy greens are available on the market. Several factors should be considered in selecting appropriate varieties. Yield, of course, is important to every grower. However, this should not be the sole factor in determining variety. Disease resistance/tolerance is important in many of these crops and should be critically examined. Buyer preference and market acceptability are probably two of the most important factors to consider. Horticultural characteristics such as product color, growth habit and shape should also be considered. Finally, the variety should be adapted to the area in which it is to be grown.

Local variety trials are a good source of information regarding variety selection. With any new variety, always try a small planting of the variety first before adapting it to your operation. Also, give every new variety at least a couple of tries before making a decision on its use for your production system. Environmental conditions can strongly influence varietal performance. Therefore, conditions in one year may not produce the same results in another year for a given variety. Good varieties are adaptable over a wide range of conditions. Tables 3 and 4 show some recommended varieties for Georgia production of cabbage and leafy greens.

Table 3. Cabbage varieties recommended for production in Georgia

Variety	Color	Head Size	Maturity	Shape
A&C No. 5 Plus	blue-green	medium	91 days	flat-round
Blue Bayou	blue-green	medium	78 days	semi-round
Blue Vantage	blue-green	4-6 pounds	72 days	round
Bravo	blue-green	4-8 pounds	85 days	round
Constanza	blue-green	4-6 pounds	90 days	round
Crimson	red	small-medium	82 days	round
Fortuna	green-blue	4-6 pounds	90 days	round
Hercules	blue-green	medium	91 days	flat-round
Izalco	blue-green	medium	105 days	round
Quisto	blue-green	medium	89 days	round
Red Dynasty	red	medium-large	70 days	round-oval
Red Rookie	red	3 pounds	78 days	round
Rio Verde	blue-green		85 days	flattened
Royal Vantage	blue-green	3 pounds	102 days	round
Savoy Ace	dark green	2 pounds	80 days	round
Savoy King	green	4 pounds	111 days	semi-flat
Solid Blue No. 780	blue-green	3-4 pounds	78 days	round
Solid Blue No. 790	blue-green	3-4 pounds	79 days	round

Table 4. Varieties of collard, turnip, mustard and kale recommended for production in Georgia

Collard	Turnip	Mustard	Kale
Blue Max Champion Flash Georgia Heavi Crop Top Bunch Vates	Alamo All Top Just Right Purple Top Seven Top Shogoin White Globe	Florida Broadleaf Slobolt Southern Giant Curled Tendergreen	Blue Armor Blue Knight Vates

SOIL AND FERTILIZER MANAGEMENT Darbie M. Granberry, William Terry Kelley and George E. Boyhan, Extension Horticulturists

Georgia's climate, stretching from the warm Coastal Plain in the south to the cool mountain area in the northern region of the state, provides a long growing season for producing cabbage and leafy greens. Although these crops grow best in light, fertile, well-drained soils, when production is properly managed, they can be grown successfully in a wide range of soil types throughout Georgia.

Soil Management

Plants depend on the soil for physical support, nutrients and water. The degree to which the soil adequately provides these factors depends upon topography, soil type, soil structure and soil fertility. Under cultivated conditions, soil and fertilizer management are two key factors influencing plant growth and yield.
Tillage is a general term for any operation that disrupts and/or moves the soil, typically within 10 to 12 inches of the soil surface. Land preparation involves one or more tillage operations that loosens, pulverizes, smooths or firms the soil and makes it more conducive to plant establishment and root growth.

Growth of cabbage and leafy green roots is influenced (and in many cases is limited) by the soil profile. Hard pans, clay pans and generally compacted soil restrict root growth. This, in turn, reduces nutrient and water uptake, limits plant growth and reduces yields. Although cabbage and leafy greens are shallow rooted, under favorable conditions and in properly prepared soil, roots will grow to a depth of 18 to 24 inches.

Tillage with a moldboard ("bottom") plow provides the greatest soil volume conducive to vigorous root growth. Disking after moldboard plowing recompacts soil.
Compaction pans are present in many Georgia soils. They are usually formed by machinery and, when present, are normally at or just below plow depths. Even though compaction pans may be only a few inches thick, their inhibitory effects on root growth can significantly reduce yields of greens and cabbage.

If a compaction pan exists just below or near moldboard plow depth, disrupting this hard pan by subsoiling to a depth of 16 to 18 inches will allow the development of a more extensive root system and increase water infiltration.

If a lot of plants or plant residue is on the soil surface, disking (or mowing, then disking) is helpful before moldboard plowing. Immediately prior to seeding or transplanting, final soil preparation (to ensure a crust-free, weed-free friable soil) can be accomplished with a rotary tiller, bed press, bedding disk or double disk hiller with a leveling board.

Cabbage and leafy greens may be planted or transplanted on flat or raised beds. A raised bed will warm up more quickly and enhance earlier growth. Cabbage and leafy greens do poorly in excessively wet soils. Raised beds facilitate drainage and help prevent "wet feet" in low or poorly drained soils. Keep in mind, however, that cabbage or leafy greens planted on raised beds may require more irrigation during drought conditions.

Lime and fertilizer management refers to the application of optimal amounts of lime and fertilizer (or nutrient-containing materials) at the most appropriate time(s) and by the most effective method.

Fertilizer Management

Recommendations based on soil tests result in the most effective lime and fertilizer management program possible. However, recommendations can be accurate only if valid soil sampling procedures are used to collect the samples submitted for analysis. To be beneficial, a soil sample must reliably represent the field or "management unit" from which it was taken. Improperly collected, compiled or labeled soil samples are of dubious benefit and may even be detrimental. If you have questions about soil sampling, please contact your county Extension office for more information. Recent technological advances have made it possible to use quadrant sampling or global positioning techniques to tune fertility recommendations more finely, which can result in more uniform fertility throughout a given field.
Recommending a specific fertilizer management program that has universal application for all cabbage and leafy greens fields is impossible. In addition to crop nutrient requirements and soil types, fertilizer recommendations should take into consideration soil pH, residual nutrients and inherent soil fertility. Therefore, fertilizer recommendations based on soil analysis have the greatest potential for providing cabbage and leafy greens with adequate, but not excessive, fertility. Apply only the needed amounts of fertilizer for optimum growth and yield. Excessive fertilizer application wastes fertilizer, encourages luxury consumption of plant nutrients and may cause fertilizer burn

Soil pH

Soil pH influences plant growth, the availability of nutrients and the activities of microorganisms in the soil. Keeping soil pH in the proper range is important for production of the best yields of high quality cabbage and leafy greens. Soil test results indicate soil pH levels and are used to recommend the amount of lime required to raise the pH to the desired range.

The optimum pH range for cabbage and leafy greens production is 6.0 to 6.5. Coastal Plain soils, which predominate in South Georgia, become strongly acid (pH 5 or less) with time if lime is not applied. A soil test is essential for determining how much lime should be applied.

Calcium (Ca) has limited mobility in soil; therefore, lime should be broadcast and thoroughly incorporated to a depth of 6 to 8 inches to neutralize the soil acidity in the root zone. To allow adequate time for neutralization of soil acidity (raising the pH), lime should be applied and thoroughly incorporated two to three months before seeding or transplanting. However, if application cannot be made this early, liming will still be beneficial if applied and incorporated at least one month prior to seeding or transplanting.

Generally, maintaining a soil pH of 6.0 to 6.5 will provide adequate soil test Ca levels. When soil test Ca levels fall below 350 to 400 pounds per acre, calcium deficiency problems may develop. Because calcium levels can vary considerably in a field, soil test calcium levels on Coastal Plain soils should be maintained at 500 pounds per acre or slightly above. If the soil pH is between 6.0 and 6.5 and the soil test Ca level drops below 500 pounds per acre on Coastal Plain soils, apply 800 to 1,000 pounds of calcium sulfate (gypsum) per acre.

Two liming materials commonly available in Georgia are calcitic and dolomitic limestone. In addition to calcium, dolomitic limestone contains 6 percent to 12 percent magnesium. Because Coastal Plain soils are inherently low in magnesium, dolomitic limestone is usually the preferred liming material.

Phosphorus and Potassium Recommendations

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

Fertilizer Recommendations for Cabbage and Leafy Greens

Ratings	Low	Medium	High	Very High
Recommended P	160	110	60	0
Recommended K	160	110	60	0

P – pounds of P₂O₅ recommended per acre
K – pounds of K₂O recommended per acre
NOTE: If soil testing is done by a lab other than the University of Georgia Soil Testing Laboratory, the levels recommended above may not apply.

All the recommended phosphorus should be applied during or near the time of transplanting. One-third to one-half of the potassium should either (1) be applied in two bands, each 2 to 3 inches to the side and 2 to 3 inches below the level of plant roots or (2) be incorporated into the bed prior to seeding or transplanting. Broadcasting over the entire field is usually less effective than banding. An acceptable alternative to field broadcasting is the "modified broadcast" method by which a preplant fertilizer containing one-third to one-half of the nitrogen and potassium and all the recommended phosphorus and micronutrients is broadcast in the bed area only. For example, on a 72-inch-wide bed, a swath (60 to 72 inches wide) of fertilizer is uniformly applied centered over the bed. Incorporation by rotary tilling will help reduce water and wind movement of the fertilizer and will also place some fertilizer in the root zone. The remainder of the recommended nitrogen and potassium should be applied in one to three applications as needed. It can be banded in an area on both sides of the row just ahead of the developing root tips. On sandy soils, the maximum number of applications is usually more effective.

Nitrogen Recommendations

For production of cabbage and leafy greens, Coastal Plain soils require 175 to 225 pounds of nitrogen (N) per acre. Extremely sandy soils may need additional N or an increased number of applications. Increasing the number of applications may prove beneficial because it will cut down on the amount lost to leaching from adding too much fertilizer at one time. Piedmont, Mountain and Limestone Valley soils usually require 150 to 180 pounds of N per acre for cabbage and greens production.

Required N rates will vary depending on season rainfall, soil type, soil temperature, irrigation, plant population, and method and timing of applications.

For typical Coastal Plain soils, one-fourth to one-third of the recommended nitrogen should be incorporated in the bed prior to seeding or transplanting. Broadcasting over the entire field is usually less effective than banding.

An acceptable alternative to field broadcasting is the "modified broadcast" method (described under Phosphorus and Potassium Recommendations). Incorporation by rotary tilling will help reduce water and wind movement of the fertilizer and will place some fertilizer in the root zone. Apply the remaining recommended N in one to three applications as needed. It can be banded in an area on both sides of the row just ahead of the developing root tips. For heavier Piedmont, Mountain and Limestone Valley soils, one or two applications are usually sufficient.

Magnesium, Sulfur, Zinc and Boron Recommendations

If the soil test indicates magnesium is low and if lime is recommended, apply dolomitic limestone. If magnesium is low and lime is not recommended, apply 25 pounds of elemental magnesium per acre. Apply a minimum of 10 pounds of sulfur per acre, 1 pound of actual boron per acre, and, if soil test indicates zinc is low, 5 pounds of actual zinc per acre. Sulfate of potash magnesia (Sul-Po-Mag or K-Mag) may be used to supply a portion of the recommended K₂0 and to supply magnesium (Mg) and sulfur (S).

Starter Fertilizer Solution

Liquid fertilizers applied to the soil around plant roots are called starter solutions. They promote rapid root development and early plant growth. Starter solutions for cabbage and leafy greens transplants should contain a high rate of phosphorus (an approximate ratio of 1 nitrogen: 3 phosphorus: 0 potassium is common) and should be mixed and applied according to the manufacturer's directions. Most starter solutions consist of 3 pounds of a formulated material (such as 10-34-0, which weighs approximately 11 pounds/gallon) mixed in 50 gallons of water. Approximately ½ pint of the starter solution is normally applied per plant. Application of about 100 to 150 pounds per acre of a starter fertilizer promotes earlier growth, particularly in cool/cold soils. For early growth stimulation, pop-up fertilizer should be banded 2 to 3 inches to the side of the plants and 2 to 3 inches below the roots. In addition to supplying phosphorus, which has limited availability in cold soils, the starter solution supplies water and firms the soil around roots (eliminating air pockets, which cause root drying). However, a starter solution is no substitute for adequate rainfall or irrigation after transplanting.

Mix and apply starter fertilizer according to the manufacturer's recommendations. If it is too concentrated, a starter solution can kill plant roots and result in dead or stunted plants. When mixing and applying from a large tank, mix a fresh solution only after all the previous solution is used from the tank. This helps prevent the gradual increase in concentration that occurs when a portion of the previous mix is used for a portion of the water component in subsequent batches.

Foliar Fertilizer Application

The fact that plants can absorb a number of fertilizer elements through their leaves has been known for some time. However, leaves of many vegetable plants are not especially well adapted for absorbing nutrients because they have a waxy cuticle. In fact, plants may appear to benefit from foliar uptake when the actual cause of improvement may be from the component of the nutrient spray that reaches the soil and provides essential nutrients for subsequent root uptake.

The effectiveness of applying macronutrients such as nitrogen, phosphorus and potassium to plant leaves is questionable. It is virtually impossible for greens (waxy leaved cabbage, collard and kale) to absorb enough N, P or K through their leaves to meet their nutritional requirements; furthermore, they are unlikely to absorb sufficient amounts of macronutrients to correct major deficiencies. Although nitrogen may be absorbed within 24 hours after application, up to four days are required for potassium uptake, and seven to 15 days are required for phosphorus to be absorbed from foliar application.

The crucial question is whether foliar N, P or K actually increases yield or enhances quality. Although some growers feel that foliar fertilizer should be used to supplement a soil-applied fertilizer program, research findings do not support this practice. If proper fertilizer management of soil-applied nutrients is used, supplementation by foliar fertilization is not usually required.

Foliar nutrients often are expected to cure a variety of plant problems, many of which may be unrelated to nutrition, such as reducing stress, aiding in healing frost- or hail-damaged plants or increasing plant resistance to various stresses and pests. Nutrients are effective as long as they are supplying a nutritional need; however, neither soil-applied nor foliar-applied nutrients are capable of performing miracles.

After frost or hail occurs, some cabbage and leafy greens growers apply foliar nutrients to give the plants an "extra shot" to promote rapid recovery. However, if a proper fertilizer program is being used before foliage damage occurs, the plants don't need additional fertilizer. What they do need is time and the proper environment for the normal recovery processes to occur. The likelihood of deriving significant nutritional benefits from a foliar application of fertilizer to plants that have lost some of their leaves (or have a large proportion of their leaves severely damaged) is questionable.

Foliar application of sulfur, magnesium, calcium and micronutrients is helpful in correcting deficiencies. To alleviate boron deficiency, apply water-soluble boron (l lb/boron per acre). Magnesium sulfate (3 lb/acre) can be applied to correct a magnesium deficiency. CaB, a commercially available formulation containing 2 percent boron and 6 percent calcium, can be applied at the rate of 2 quarts per acre to help alleviate calcium and boron deficiencies. Other acceptable foliar fertilizer formulations may also be available. When using foliar fertilizers (1) check the label for percent active ingredients - know what and how much fertilizer you are applying - and (2) apply according to label instructions. Apply foliar fertilizers only if a real need for them exists and only in quantities recommended for foliar application. Application of excessive amounts can cause fertilizer burn and/or toxicity problems.

Tissue Analysis

Fertilizer recommendations provide general guidelines for the application of fertilizers to crops. Actual amounts needed will vary depending on soil type, the amount of leaching and crop growth. Routine tissue analyses (tables 5 and 6) and sap tests (Table 7) are excellent tools for fine tuning fertilizer management.

Presently we do not have tissue and sap tests recommendations for all vegetable crops. We will provide recommendations for other vegetable crops when they are developed.

Table 5. Plant tissue analysis critical values for cabbage

1 Most recently mature leaf sampled.
2 Wrapper leaf sampled.
Adapted from Plant Tissue Analysis and Interpretation for Vegetable Crops in Florida. University of Florida Publication SS-Vec-42. January 1991.

Table 6. Injection schedule for N and K for cabbage and collard planted two rows per 6-foot bed on soils testing medium for K

Crop	Total Nutrients (lb/A)			Crop Development		Injection (lb/A/day)1
	N	K2O		Stage	Weeks2	N	K2O
Cabbage	175	110		1	3	1.5	1.0
Collard	175	110		2	7	2.5	1.5
				3	2	1.5	1.0

1 Actual amounts may vary depending on preplant fertilizer and soil test K.
2 Starting from seeding or transplanting. First two weeks may be omitted if 25 percent of total N and K were applied preplant.
Adapted from Vegetable Production Guide for Florida. Pub. No. SP 170. University of Florida Cooperative Extension Service. April 1999.

Table 7. Plant tissue analysis critical values for collard

1 Tops of young plants sampled.
2 Most recent mature leaf sampled.
Adapted from Plant Tissue Analysis and Interpretation for Vegetable Crops in Florida. University of Florida Publication SS-Vec-42. January 1991.

Table 8. Sufficiency ranges for petiole sap testing in collard

Crop Development Stage	Fresh Petiole Sap Concentration (PPM)
	NO3-N	K
Six-leaf Stage	800-1,000	NR
One Week Prior to First Harvest	500-800	NR
First Harvest	300-500	NR

NR - No recommended ranges have been established.
Adapted from Vegetable Production Guide for Florida. Publication No. SP 170. University of Florida Cooperative Extension Service. July 1996.

Cabbage and leafy greens are susceptible to a number of diseases that may seriously injure or even destroy the crop. Some diseases may cause only minor spotting, but because the leaves are consumed, the quality may be reduced below market standards. Prevention is the key to controlling all diseases affecting crucifers. Some of the diseases can be controlled with timely fungicide applications and others must be prevented altogether. This section will aid in the identification of diseases and discuss environmental conditions that favor disease development. Sources of infection are discussed relative to specific diseases on specific crops.

Black Leg

Black leg, caused by the fungus Phoma lingam, is another disease that can cause serious loss to cabbage. Plants are usually infected in seedbeds. Usually the first symptom is an oval, depressed, light brown canker near the base of the stem. The canker enlarges until the stem is girdled. Circular light brown spots also appear on the leaves. Soon after cankers or spots begin to form, they are marked with numerous black dots that are the fruiting bodies of the fungus. The fungus lives for at least three years in the soil and is carried on and in the seeds. Black leg is influenced by environmental conditions, with the severity of the disease in direct proportion to the amount of rainfall received. The fungus grows well at all temperatures suitable to cabbage.