Commercial Pepper Production Handbook

This publication is a joint effort of the seven disciplines that comprise the Georgia Vegetable Team. It is comprised of 14 topics on pepper, including history of pepper production, cultural practices, pest management, harvesting, handling and marketing. The publication provides information that will help producers improve the profitability of pepper production, whether they are new or experienced producers.

Peppers are an important crop for Georgia growers, but successful pepper production is not easily achieved. Pepper production requires highly intensive management, production and marketing skills, and a significant investment. Per-acre cost of production is high, and yields can be severely limited by pest problems or environment. Pepper production is complex. Expertise in the areas of cultural practices, soils and fertility management, pest control, harvesting, post-harvest handling, marketing, and farm record keeping is crucial to profitable production.

In writing this publication, the authors have strived to provide a thorough overview of all aspects of pepper production. Chemical pest control recommendations are not included, however, as these change from year to year. For up-to-date chemical recommendations, see the current Georgia Pest Management Handbook, or check with your county extension office.

Pepper History, Scope, Climate and Taxonomy

Pepper (Capsicum sp.) is one of the most varied and widely used foods in the world. From the various colors to the various tastes, peppers are an important spice commodity and an integral part of many cuisines. Peppers originated in the Mexico and Central America regions. Christopher Columbus encountered pepper in 1493 and, because of its pungent fruit, thought it was related to black pepper, Piper nigrum, which is actually a different genus. Nevertheless, the name stuck and he introduced the crop to Europe, and it was subsequently spread into Africa and Asia.

Peppers were important to the earliest inhabitants of the western hemisphere as much as 10,000 to 12,000 years ago. Plant remnants have been found in caves in the region of origin that date back to 7,000 B.C. The Incas, Aztec and Mayans all used pepper extensively and held the plant in high regard. Many of the early uses of pepper centered around medicinal purposes. Pepper has been credited with any number of useful cures and treatments, some of which are valid and some of which are probably more folklore.

Virtually every country in the world produces pepper. The bulk of pepper produced in the United States is sweet pepper, but hot peppers dominate in other countries. Globally, pepper production exceeds 14 million metric tons. California is the leading producer of sweet peppers in the United States. Fresh market production is a large part of the U.S. market, although processed peppers are common in all parts of the world as dried, pickled or otherwise processed products.

Pepper production has increased in recent years worldwide. That could be at least in part because of the high nutritional value of pepper. One medium green bell pepper can provide up to 8 percent of the Recommended Daily Allowance of Vitamin A, 180 percent of Vitamin C, 2 percent of calcium and 2 percent of iron. Additionally pepper contains significant amounts of A and the B vitamins.

All peppers are members of the Solanacea family, which also includes tomato, tobacco, eggplant and Irish potato. There has been much debate over the years as to how many species of Capsicum truly exist. The number has fluctuated over the centuries from 1 to 90. Currently five species are recognized as domesticated. Among these are C. annum, which includes the bulk of cultivated types including bell, yellow wax, cherry, ancho, cayenne, jalapeno and serrano. C. chinense includes the habaneros and Scotch bonnet. Tobasco is the most notable variety in the C. frutescens species. The only important variety in the C. battacum species is the Yellow Peruvian Pepper. C. pubescens includes ‘manzano’ and ‘peron’ pod types. The classification of species will obviously continue to evolve in the future. There are an additional 20 or more species of wild types.

A phenolic compound called capsaicin is responsible for the pungency in peppers. The compound is related to vanillin. It is not located in all parts of the fruit, and various cultivars differ markedly in their content of this chemical. Pepper is considered a self-pollinating crop although some out crossing will occur. Although grown as an annual crop due to its sensitivity to frost, pepper is actually a herbaceous perennial and will survive and yield for several years in tropical climates.

Peppers grow well in warm climates with a relatively long growing season. Most cultivated peppers require around 75 days from transplanting to first harvest and can be harvested for several weeks before production wanes. Ideal temperatures for pepper growth are in the range of 75-89 degrees F during the day and 65-75 degrees F at night. Significantly higher or lower temperatures can have negative effects on fruit set and quality.

Cultural Practices and Varieties

Soil Requirements and Site Preparation

Peppers can be produced on a wide variety of soil types. They grow best, however, in deep, medium textured sandy loam or loamy, fertile, well-drained soils. Avoid sites that tend to stay wet. Also, rotate away from fields that have had solanaceous crops within the past 3 or 4 years.

In field production, plants depend on the soil for (1) physical support and anchorage, (2) nutrients and (3) water. The degree to which the soil adequately provides these three factors depends upon topography, soil type, soil structure and soil management.

For pepper production, proper tillage is crucial for adequate soil management and optimal yields. Land preparation should involve enough tillage operations to make the soil suitable for seedling (or transplant) establishment and to provide the best soil structure for root growth and development.

The extent to which the root systems of pepper plants develop is influenced by the soil profile. Root growth will be restricted if there is a hard pan, compacted layer or heavy clay zone. Peppers are considered to be moderately deep rooted and, under favorable conditions, roots will grow to a depth of 36 to 48 inches. But the majority of roots will be in the upper 12 to 24 inches of soil. Since root development is severely limited by compacted soil, proper land preparation should eliminate or significantly reduce soil compaction and hard pans.

Tillage systems using the moldboard (“bottom”) plow prepare the greatest soil volume conducive to vigorous root growth. This allows more extensive root systems to develop, which can more efficiently access nutrients and water in the soil. Discing after moldboard plowing tends to re-compact the soil and should be avoided.

Compaction pans are present in many soils. They are formed principally by machinery and, when present, are normally located 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 pepper yields.

If a compaction pan exists just below or near moldboard plow depth, this hard pan can be disrupted by subsoiling to a depth of 16 to 18 inches to allow the development of a more extensive root system. Subsoiling also helps increase water infiltration.

If there is an abundance of plants or plant residues on the soil surface, discing or mowing followed by discing is usually advised prior to moldboard plowing. Immediately prior to mulch installation or transplanting, do final soil preparation and/or bedding with a rotary tiller, bedding disc or a double disc hiller in combination with a bedding press or leveling board. This provides a crustless, weed free soil for the installation of plastic mulch or the establishment of transplants.

Peppers are usually transplanted into plastic mulch on raised beds. A raised bed will warm up more quickly in the spring and therefore may enhance earlier growth. Since peppers do poorly in excessively wet soils, a raised bed improves drainage and helps prevent water logging in low areas or poorly drained soils. Raised beds are generally 3 to 8 inches high. Keep in mind, however, that peppers planted on raised beds may also require more irrigation during drought conditions.

Cover Crops and Minimum Tillage

Winter cover crops help protect the soil from water and wind erosion. When incorporated into the soil as “green manure,” cover crops contribute organic matter to the soil.

Soil organic matter consists of plant and ani-mal residues in various stages of decay. Organic matter (1) improves soil structure (helps reduce compaction and crusting), (2) increases water infiltration, (3) decreases water and wind erosion, (4) increases the soil’s ability to resist leaching of many plant nutrients, and (5) releases plant nutrients during decomposition.

Planting cover crops and the subsequent incorporation of the green manure into the soil enhances pepper production in Coastal Plains soils. Use wheat, oats, rye or ryegrass as winter cover crops. If these non-nitrogen fixing cover crops are to be incorporated as green manure, provide them with adequate nitrogen during their growth. This increases the quantity of organic matter produced and provides a carbon: nitrogen (C:N) ratio less likely to immobilize nitrogen during decomposition.

As a general rule, when non-leguminous organic matter having a C:N ratio exceeding 30 to 1 is incorporated, a supplemental nitrogen application (usually 20 to 30 pounds of nitrogen per acre) prior to incorporation is recommended. The exact rate required will depend on the C:N ratio, soil type and amount of any residual nitrogen in the soil. Plow green manure crops under as deeply as possible with a moldboard plow at least two weeks prior to installing mulch or transplanting peppers.

Planting peppers in reduced tillage situations has been tried with modest success. Often these cover crops can be killed with a burn down herbicide. Then pepper is either transplanted directly into the cover or a narrow strip is tilled and prepared for transplanting while leaving the residue between rows.

The primary encumbrance to success in these systems is adequate weed and disease control. Because of this, reduced tillage is used only on a limited basis in commercial pepper production. With advances in weed and disease control technology, this type of production may become more feasible in the future.

Windbreaks

Crop windbreaks can act as a crop protection aid. Frequency or intervals between windbreaks is dictated by distance between pepper rows, spray or harvest alleyway intervals, land availability and equipment characteristics. For instance, bed arrangements may be such that a windbreak is present between every set of four, six or eight beds.

In general, close windbreaks give the best wind protection and help moderate the pepper plants’ microenvironment and enhance earliness. Especially on sandy soils, windbreaks reduce damage from sand-blasting of plants and small fruit during early spring. Sandblasting can be more of a problem with plastic mulch since the soil particles are carried easily by the wind across the field.

Regardless of the species selected as a windbreak, it should be planted early enough to be effective as a windbreak by the time peppers are transplanted. Establishment of a windbreak crop during the fall or early winter should ensure enough growth for an effective windbreak by spring pepper planting time. Wheat, oats or rye all make good windbreak crops. Pepper beds can be established between the windbreaks by tilling only in the bed area.

To minimize insect migration to the pepper crop, destroy windbreak crops by herbicides, mowing and/or tillage before they lose their green color and begin to die back.

Transplanting

Seeding pepper directly into the field is not recommended due to the high cost of hybrid seed and the specific conditions required for adequate germination. Most pepper is transplanted to the field from greenhouse-grown plants. Direct seeding has other disadvantages:

Typically, 5- to 6-week old pepper seedlings are transplanted into the field. As with most similar vegetable crops, container-grown transplants are preferred over bare root plants. Container grown transplants retain transplant growing medium (soil-substitute) attached to their roots after removal from the container (flat, tray). Many growers prefer this type transplant because (1) they are less subject to transplant shock; (2) they usually require little, if any, replanting; (3) they resume growth more quickly after transplanting; and (4) they grow and produce more uniformly.

Pepper transplants should be hardened off before transplanting in the field. Hardening off is a technique used to slow plant growth prior to field setting so the plant can more successfully transition to the less favorable conditions in the field. This process involves decreasing water, nutrients and temperature for a short period prior to taking the plants to the field.

For maximum production, transplants should never have fruits, flowers or flower buds before transplanting. An ideal transplant is young (6 to 8 inches tall with a stem approximately ⅜ inch to ¼ inch in diameter), does not exhibit rapid vegetative growth, and is slightly hardened at transplanting time. Rapid growth following transplanting helps assure a well established plant before fruit develops.

Set transplants as soon as possible after removing from containers or pulling. If it is necessary to hold pepper plants for several days before transplanting, keep them cool (around 55-65 degrees F if possible) and do not allow the roots to dry out prior to transplanting. When setting plants, place roots 3 to 4 inches deep. Setting plants at least as deep as the cotyledons has shown to enhance plant growth and earliness. Completely cover the root ball with soil to prevent wicking moisture from the soil. Peppers grow best if nighttime soil temperatures average more than 60 degrees F.

At transplanting, apply an appropriate fertilizer starter solution (see Fertilizer Management section). After transplanting (especially within the first 2 weeks) maintain soil moisture so plant roots can become well established.

Plant Spacing

Optimal plant population per acre depends upon plant growth habit (compact, medium, spreading), plant size (small, medium, large) at maturity, vigor of specific cultivars, climate, soil moisture, nutrient availability, management system and soil productivity. Adequate populations for the many different types and cultivars of peppers range from approximately 7,500 to 14,500 plants per acre.

Sweet bell pepper types are more compact than many other kinds of pepper and, with traditional plastic mulch production, are usually planted with two rows on each bed with plants spaced 12 inches apart. The beds are usually 60 to 72 inches apart from center to center and the rows on the bed are generally about 14 to 18 inches apart. On bare ground, space rows 36 to 42 inches apart with 12 inches to 16 inches between plants in the row. Normally from 12,000 to 15,000 plants per acre are considered adequate for bell pepper production. For other kinds of peppers, which produce larger type plants, decrease the population accordingly.

Varieties

Select varieties on the basis of marketable yield potential, quality, market acceptability and disease resistance or tolerance. While there are numerous commercially available varieties that will perform well under Georgia conditions, these varieties perform differently under various environmental conditions.

When selecting a variety, yield should not be the only selection criteria. Plants need to produce adequate foliage to protect fruit from sunburn. Market preferences for fruit size and color should also be considered. Disease resistance is more important with diseases for which there are no other good management options. Basically, a variety must be adaptable to the area, produce a competitive yield and be acceptable to buyers.

All commercially important bell peppers grown in Georgia belong to the genus Capsicum annuum. Some pungent varieties encompass other species. Table 1 lists varieties that have performed well in Georgia or in similar areas of the southeastern United States. Notations in the disease resistance column indicate either resistance or tolerance. Some varieties may not exhibit complete resistance to the disease listed.

Table 1. Bell pepper varieties that have exhibited acceptable performance either in variety trials or in grower fields in Georgia.
Variety	Days to Maturity	Color	Shape	Disease Resistance
X3R Aladdin	70	Green to Yellow	Large blocky	BLS¹²³, TMV
Alliance	72	Green to Red	Blocky	BLS¹²³⁵, PHY, CMV, PVY, PMV
X3R Aristotle	72	Green to Red	3-4 Lobed	BLS¹²³, TMV, PVY
Brigadier	71	Green to Red	Large blocky	BLS¹²³, PVY
Camelot X3R	75	Green to Red	Elongated	BLS¹²³, TMV
Commandant	80	Green to Red	Deep blocky	BLS¹²³, TMV, PVY, PMV
Crusader	75	Green to Red	Large blocky	BLS¹²³, TMV, PVY, S, PMV
Excursion II	75	Green to Red	Large blocky	BLS¹²³, TSW, TMV, PVY
Heritage	75	Green to Red	Blocky	BLS¹²³, TSW
King Arthur	68	Green to Red	3-4 Lobed	BLS¹²³, TMV, PVY, TEV
Paladin	72	Green to Red	Deep blocky	PHY, TMV
Patriot	70	Green to Red	Deep blocky	BLS¹²³, PVY
Plato	75	Green to Red	Blocky	BLS¹²³, TSW
X3R Red Knight	63	Green to Red	Large blocky	BLS¹²³, PVY
Revolution		Green to Red	Blocky	BLS¹²³⁵, CMV, PHY
Sentry	75	Green to Red	Very blocky	BLS¹²³, S
Stiletto	75	Green to Red	Blocky	BLS¹²³, TSW
Summer Sweet 8610	73	Green to Yellow	Deep blocky	BLS¹²³, TMV, PVY
X3R Wizard	75	Green to Red	Deep blocky	BLS¹²³, TMV
BLS = Bacterial Leaf Spot; PHY = Phytothphora capsici; TMV = Tomato Mosaic Virus; PVY = Potato Virus Y; CMV = Cucumber Mosaic Virus; S = Stipling; TEV = Tobacco Etch Virus; PMV = Pepper Mottle Virus

Transplant Production

Modern production techniques coupled with more costly hybrid seed make pepper transplant production a cost effective alternative to direct seeding. Because of the high cost of production associated with plastic mulch use, staking and drip irrigation, growers can not afford to have a less than perfect stand. This can only be achieved with transplants.

Growers wishing to use transplants but not willing or able to produce transplants themselves need to plan ahead to ensure sufficient plants can be produced in a timely manner to meet their needs. This will mean contracting and coordinating with a transplant grower at least 3-4 months before field planting. If you want to contract with a transplant grower, you need to specify the cell size desired, the variety to be planted, and a specific delivery date. Also, determine whether the transplant grower or the pepper grower will furnish the seed.

Most greenhouse operations use mechanical seeders to plant the seed into the trays or flats. These seeders require that the seed be coated so all seeds are the same size. Coated seed will increase seed costs and any surplus coated seed cannot be returned to the seed company. The cost to the grower for this type transplant will vary depending on the volume ordered and the cell size of the tray.

Containerized plant producers specialize in growing plants in greenhouses designed specifically for the production of transplants. These special houses use plant trays designed to produce the maximum number of transplants per square foot of house space. Plants are usually grown in Styrofoam or plastic trays, and the cell size in these trays determines the number of transplants per tray and the price per thousand for transplants. In general, the larger cell size will produce a larger plant with a greater stem diameter; producing plants in large cells is more costly, however, because there are fewer plants per square foot.

Producing Transplants

Pepper transplant production is usually done in a protected structure such as a greenhouse. Other protected structures — plastic row covers and high tunnels — can be used for in-ground or bed production. In-field production is also possible in high-density plantings that are pulled bareroot, bundled, crated and shipped to growers. These types of production are rarely used any longer because of problems with disease and temperature control. Peppers usually command a high enough price to offset the cost of using a heated greenhouse for transplant production. This, of course, is only the case for larger growers and dedicated greenhouse operations; smaller growers will find it economical to contract production.

For peppers, a cell size of 1-1.5 inches is recommended. This will produce a plant of sufficient size for easy handling while efficiently using greenhouse space. This cells size will produce a 4- to 6-inch tall pepper plant at transplanting time. Peppers are relatively slow growing in comparison to many other transplants and a minimum of 5-7 weeks is needed to produce a transplant of sufficient size for easy handling.

Pepper seed will germinate best at a temperature of approximately 80 degrees F. Wide fluctuation in greenhouse temperatures will cause delayed emergence of pepper plants. Bottom heat, approaching 80 degrees F, will greatly enhance uniform emergence of seedlings in about 8 days after seeding. Coated seed may require more days for germination and plant emergence. Direct sunlight in greenhouses that leads to temperatures at 90 degrees F or above can be detrimental to pepper seed germination and growth. Shade cloth of 30-50 percent may help alleviate this problem. This is particularly true during summer transplant production for a fall crop.

Approximately 7 ounces of pepper seed is required to produce 10,000 transplants. This can vary significantly based on variety, seed size for a particular lot, and percent germination. Many seed companies now sell seed by the count. Each seed lot will have been counted, which, when coupled with the percent germination, gives growers a more accurate method for purchasing seed.

Common containers for transplant peppers include Styrofoam, plastic flats and inserts, and rigid plastic trays. The Styrofoam and rigid plastic trays are reusable; the inserts used with the flat and insert system are disposed of. Carefully wash reusable containers from one season to the next to prevent disease spread.

A number of commercial potting mixes are available for use in pepper transplant production. Most of these are peat-based media with various additives to improve texture, wettability, pH and fertility. The finer textured media are best for starting seed and will usually have a higher percentage of vermiculite. These media will generally be uniform from one batch to another and will help eliminate weed and disease related problems. Three cubic feet of potting mix should fill from 16 to 20 flats that have a cell size 1.5 inches x 1.5 inches x 2.25 inches. Three cubic feet of potting mix should produce 1,100 to 1,400 transplants.

Plant pepper seed about 0.25 inch deep. The seed may be coated with a fungicide to help prevent dampening off. This usually will appear as a pink or purple coating on the seed. Be careful if using treated seed. If planting by hand, use rubber gloves. Workers should avoid touching their eyes or mouth when handling treated seed. Newer coating technologies are available that do not come off the seed while still offering disease prevention characteristics. Pelleted seed may also be used, especially if automated seeding equipment is to be used. The pelleting, which comes in various thicknesses, allows equipment to singulate and plant the seed.

Many potting mixes come with some fertilizer already incorporated. This media is often referred to as “being charged.” With such media, sufficient nutrients should be present for 3-4 weeks before additional fertilizer will have to be applied. Many growers prefer to use an uncharged media, since this gives them more control over when and how much fertilizer to apply. If you plan to fertilize with every irrigation, 50 ppm of a complete water-soluble, fertilizer should be sufficient. If fertilizer is only going to be applied intermittently (every third or fourth watering), then higher rates up to 200 ppm may be employed. Inexpensive electrical conductivity meters can be used to measure relative fertility. Electrical conductivity of 1.0-2.0 mS usually indicates adequate fertility in peat-based media.

An assessment of plant size may be necessary as the plants near transplanting. Plants will have to be large enough to be handled and transplanted properly, but not so large that they interfere with transplanting equipment or suffer undue stress when transplanted. Plants may require more time to grow if too short, or they may require early hardening off (see below) to slow growth.

Peppers should be hardened off prior to transplanting in the field. This usually involves reducing fertilizer application, watering and greenhouse temperatures. Some greenhouses are designed where the sidewalls can be completely opened, which should be done at this time, at least during the day. Hardening off pepper transplants will take 7-10 days. Avoid over-hardening transplants, which can delay the start of growth in the field and reduce early yields.

It may be necessary to delay planting because the field is inaccessible or because of adverse weather conditions. Under these circumstances, take care that plants are not overly stressed by heat, cold or lack of water. If they are on an enclosed trailer, it may be necessary to unload the plants and ensure adequate moisture.

Pepper Production Using Plastic Mulch

The use of plastic mulch in the production of peppers is almost universal in the Southeast. Plastic mulch is used to promote earliness, reduce weed pressure, and conserve moisture and fertilizer. Most often drip irrigation is used in conjunction with plastic mulch. There are both advantages and disadvantages to producing crops under this system.

Advantages

Plastic mulch promotes earliness by capturing heat, which increases soil temperatures and accelerates growth. Black plastic will prevent the establishment of many in-row weeds. Mulch will reduce fertilizer leaching from pepper beds and will conserve moisture by reducing soil surface evaporation. Furthermore, where fumigants are used, plastic mulch provides a barrier that increases fumigant efficiency.

Plastic mulch also keeps fruit cleaner by reducing soil spatter. When using drip irrigation, disease is often reduced because the foliage stays drier and soil is, again, not splashed onto the plant. Plastic mulch also decreases incidence of Tomato Spotted Wilt, particularly when UV-reflective mulch is used.

Disadvantages

Specialized equipment is required to lay plastic mulch, which means increased variable costs for custom application or the purchase of this equipment. Yellow and purple nutsedges are not controlled by black plastic mulch, and suitable fumigants/herbicides must be applied if nutsedge is a potential problem. The cost of plastic removal is an additional expense. In most instances, plastic mulch culture has increased yields and returns sufficiently to offset these potential disadvantages.

Types of Plastic

One to 1¼ mil black plastic is the cheapest and has traditionally been most often used in spring pepper production. Embossed plastic has a reinforced woven component that minimizes the risk of tear elongation, which may occur with wind entry through a tear. This can be important, particularly in multiple cropping operations where, for example, spring peppers may be followed by fall cucumbers.

Summer planted pepper crops for fall production cannot tolerate excessively high soil temperatures. They should be planted on white plastic, which reflects some surface heat and does not heat the soil as much. For spring production however, white is not recommended since maximum soil warming is needed.

Recently, metalized mulches have become popular. These black plastic mulches have a thin film of metal that is applied with a vacuum. The metal produces a reflective effect. Research has shown that these mulches can help reduce the incidence of Tomato Spotted Wilt Virus infection on pepper by repelling thrips. Often, these plastics are produced with a black strip down the middle with the shoulders metalized. This allows for heat retention to get the earliness effect while producing the reflective effect needed to repel thrips and reduce TSWV.

Virtually Impermeable Films (VIF) are used in some parts of the world to reduce fumigant release into the atmosphere. These films are not yet routinely available in the United States, are more expensive and, depending on the fumigant, can increase the preplant interval.

Although biodegradable plastic mulches are presently available, they have not been proven to be beneficial. Since most growers want to grow two, three or four crops using the same plastic, biodegradable plastics break down too quickly to allow this. When perfected, these materials have the potential to greatly reduce the cost of plastic removal and disposal. Growers using a biodegradable plastic mulch for the first time should test it on a small area until its effectiveness under their conditions is proven.

Bed Preparation

Bed height and width depend on several factors including soil type, bedding equipment, available plastic, etc. Standard bed heights range from 4 to 8 inches. Bed width is also dictated by equipment and grower preference. Current top widths of beds range from 28 to 36 inches. Ordinarily plastic mulch must be 20 to 24 inches wider than the bed width preferred so it will cover the sides of the bed and can be tucked under the soil to anchor the plastic. The plastic must fit firmly over the bed to minimize wind movement and facilitate planting. Cover mulch at the ends of each bed to prevent wind from getting under the plastic and fumigant from escaping. Any available opening, such as a tear or uncovered tuck, that allows wind entry will cause problems.

Use trickle or drip irrigation with plastic mulch for maximum efficiency. It is still important, however, to have optimum soil moisture during plastic application. The use of overhead irrigation requires punching additional holes in the plastic to facilitate water entry; this compromises the integrity of the plastic and reduces its effectiveness in controlling weeds and minimizing nutrient leaching.

Land preparation for laying plastic is similar to that described previously. The site should still be deep turned and rototilled. Usually a hipper is used to form a high ridge of soil down the middle of the bed to assure the bed pan is filled with soil. This creates a firm full bed. Generally, fumigant is applied as the bed pan passes and plastic is installed just behind the pan. Drip tape is installed at the same time just in front of the plastic and should be buried 1 inch below the surface to prevent “snaking” under the plastic and to reduce rodent damage. Soil moisture should be good at the time plastic is installed to ensure a good firm bed.

Fertilizer Management Under Plastic

Apply any needed lime 2 to 3 months ahead of plastic mulch installation. Preplant fertilizer application will vary with bed size and planting scheme. On larger beds (4 feet wide or greater) with double rows of peppers, it is advisable to incorporate all phosphorus and micronutrients into the bed before installation of plastic. If drip fertigation is not used, apply all the nitrogen and potassium preplant as well.

If smaller, single row beds are used, preplant application of all the needed fertilizer may cause fertilizer salt toxicity. Therefore, side-dressing is required by a liquid injection wheel, through drip irrigation, or a banded application outside the tucked portion of the bed.

Most pepper is planted where fertigation with drip irrigation is used. In these cases all the P and micronutrients and ⅓ to ½ of the N and K should be incorporated into the bed before the plastic is laid. Apply the remaining N and K through weekly fertigations beginning just after transplant establishment. The rate of application of these fertigations will change with the stage of the crop. Contact your local Georgia Cooperative Extension office for a specific schedule of fertilizer injection recommendations.

Planting into Plastic Mulch

Peppers can be transplanted with a tractor mounted implement that uses a water wheel to punch holes in the plastic at the appropriate interval. A person (or persons) riding on seats mounted behind the water wheel(s) places a transplant into the newly formed hole and covers the rootball. This approach is rather slow, and a more common practice is to use a water wheel or similar device to punch holes with a crew of people walking the field and hand setting plants. Plants are then watered with a water wagon following the setting crews.

If a fumigant is used for soil sterilization, wait the prescribed time period before punching holes into the plastic. This will ensure good fumigant activity and avoid phytotoxicity. If an appropriate waiting period is not observed prior to planting, some soil fumigants can destroy pepper transplant roots and cause stunting or plant death.

Irrigation

Irrigation is essential to produce consistent yields of high quality peppers in Georgia. Rainfall amounts are often erratic during the pepper growing season, and peppers are often grown in sandy soils that have a low water holding capacity. This combination of factors makes supplemental irrigation necessary for commercial pepper production.

Irrigation studies in the Southeast show that irrigation increases annual pepper yields by an average of at least 60 percent over dryland production. Quality of irrigated peppers is also much better. Irrigation eliminates disastrous crop losses caused by severe drought.

Peppers are potentially deep rooted (up to 4 feet). In Georgia soils, however, the effective rooting depth is generally much less. Actual root depths will vary considerably, depending upon soil conditions and cultural practices. The effective rooting depth is usually 12 to 18 inches, and half of the roots will be in the top 6 inches. These roots should not dry out or root damage will occur. Moisture stress in peppers causes shedding of flowers and young fruit, sunscalding and dry rot of fruit. The most critical stages for watering are at transplanting, flowering and fruit development.

Several types of irrigation may be used successfully on peppers in the Southeast; in Georgia, the majority of peppers are produced with drip irrigation. Ultimately, the type of irrigation chosen will depend on one or more of the following factors:

Sprinkler Irrigation

Sprinkler irrigation systems include center pivot, linear move, traveling gun, permanent set and portable aluminum pipe with sprinklers. Any of these systems are satisfactory if they are used correctly, but they are no longer commonly used in pepper production. There are, however, significant differences in initial cost, fuel cost and labor requirements among these systems.

Any sprinkler system used on peppers should be able to deliver at least an inch of water every 4 days. In addition, the system should apply the water slowly enough to prevent run-off. In sandy soils, the application rate should be less than 3 inches per hour. In loamy or clay soils, the rate should not exceed 1 inch per hour.

Sprinkler systems with a high application uniformity (center pivot, linear move and permanent set) can be used to apply fertilizer. This increases the efficiency of fertilizer use by making it readily available to the plant and reducing leaching.

Overhead irrigation also offers the most effective method of frost protection in pepper production; however, timely and complete coverage is required. The distance between sprinklers should be no more than 60 percent of the wetted diameter; place sprinklers no more than 50 percent of the sprinkler radius from the edge of the field. The nozzles should make at least one revolution per minute and should apply 0.12 to 0.15 inch of water per hour. Start sprinklers before the temperature drops to 32 degrees F (say 34 degrees F) and continue irrigating until the temperature rises and the ice begins to melt or until the wet-bulb temperature rises above 32 degrees F.

Drip Irrigation

Drip irrigation is the most popular method for pepper production in Georgia. Although it can be used with or without plastic mulch, its use is highly recommended with plastic mulch culture. One of the major advantages of drip irrigation is its water use efficiency. Studies in Florida indicate that drip irrigated vegetables require 40 percent less water than sprinkler irrigated vegetables. Weeds are also less of a problem since only the rows are watered and the middles remain dry. Some studies have also shown significant yield increases with drip irrigation and plastic mulch when compared with sprinkler irrigated peppers. The most dramatic yields have been attained by using drip irrigation, plastic mulch and supplementing nutrients by injecting fertilizers into the drip system (fertigation).

Drip tubing may be installed on the soil surface or buried 2 to 3 inches deep. When used in conjunction with plastic mulch, the tubing can be installed at the same time the plastic mulch is laid. Usually one line of tubing is installed on each bed. If two rows of peppers are planted on a bed and they are not more than 12 inches apart, then both rows can be watered from the same drip line.

A field with beds spaced 5 feet center to center will require 8,712 feet of tubing per acre (one tube per bed). The output rate of the tube is specified by the user. For discussion purposes, you can determine the needed per-acre water capacity by multiplying the output rate of the tube (per 1,000') by 8.712 (ie., on a 5' bed spacing a 4.5 gpm/1,000' output rate tube will require 39.2 gpm per acre water capacity).

The tubing is available in various wall thick-nesses ranging from 3 mils to 25 mils. Most growers use thin wall tubing (10 mils or less) and replace it every year. Heavier wall tubing can be rolled up at the end of the season and reused, but be careful removing it from the field and store in a shelter. Labor costs for removing, storing and reinstalling irrigation tubing are often prohibitive.

Excellent results have been achieved by injecting at least half of the fertilizer through the drip system. This allows plant nutrients to be supplied to the field as needed. This method also eliminates the need for heavy fertilizer applications early in the season, which tend to leach beyond the reach of root systems or cause salt toxicity problems.

Only water soluble formulations can be injected through the drip systems. Nitrogen and potassium formulations tend to be more water soluble than phosphorous and, consequently, are more easily injected. These nutrients also tend to leach quicker and need to be supplemented during the growing season. Drip systems should be thoroughly flushed following each fertilizer injection.

Water used in a drip irrigation system should be well filtered to remove any particulate matter that might plug the tubing. Test the water for minerals that could precipitate and cause plugging problems.

Scheduling Irrigation

The combined loss of water by evaporation from the soil and transpiration from plant surfaces is called evapotranspiration (ET). Peak ET rates for peppers are about 0.2 inch per day. Factors affecting ET are stage of crop growth, temperature, relative humidity, solar radiation, wind velocity and plant spacing.

Transplant peppers into moist soil and irrigate with 0.3 to 0.5 inch immediately after transplanting to settle the soil around the roots. Once a root system is established, maintain soil moisture to the 12-inch depth. The sandier soils in South Georgia have an available water holding capacity of about 1 inch per foot of soil depth. You should not deplete more than 50 percent of the available water before irrigating; therefore, when you use 0.5 inch, it should be replaced by irrigation. Soils having a higher clay content may have water holding capacities as high as 2 inches per foot. In these soils, you can deplete as much as 1 inch before irrigating. This means net application amounts should be between 0.5 and 1.0 inch per irrigation. The actual amount applied should be 10 to 20 percent higher to account for evaporation losses and wind drift.

The irrigation frequency will depend on daily evapotranspiration. In general, for sprinkler irrigated peppers during peak water use periods, sandy soils should receive 0.6 inch two or three times a week, and clay soils should receive 1.25 inches about every 5 days. Irrigation can best be managed by monitoring the amount of moisture in the soil. Soil moisture blocks can be used to measure soil moisture. For best results on peppers, maintain soil moisture below 30 centibars.

Drip irrigation systems need to be operated more frequently than sprinkler systems. Typically, they are operated every day or every other day. Do not saturate the soil with water, especially when using plastic mulch. Plastic mulch tends to keep the soil from drying out, and peppers grow poorly in waterlogged soil.

Physiological Problems

Blossom Drop and Reduced Fruit Set

Blossom drop in pepper is primarily associated with high temperatures, particularly when night temperatures are above 70 degrees F. Such night temperatures can be common during mid-summer in Georgia. Spring production is best for peppers in reducing the incidence of blossom drop.

Other stress factors such as inadequate moisture can also contribute to blossom drop. Fruit load can also affect blossom retention. As fruit are set on a plant, additional flowers may drop or abort because the plant does not have sufficient resources to continue setting fruit.

Night temperature of 55 degrees F and below can also reduce fruit set by delaying flowering, affecting pollen viability, and affecting fruit morphology and size. Early plant growth is important in pepper production. Plants that have not reached sufficient size before flowering may produce fewer and smaller peppers. Maintaining optimum fertilization and water are important to ensure rapid early growth.

Use of floating row covers can help prevent cool temperature blossom drop during fall production, and black plastic mulch can help maintain warmer soils with greater moisture retention in the spring to ensure rapid growth.

Blossom-End Rot

Blossom-end rot is a physiological disorder of several vegetables including tomato, watermelon, squash and pepper. It is characterized as a dark brown to black necrotic region on the blossom end of developing fruit. This disorder is associated with calcium deficiency. Fruit losses can vary from negligible to economically devastating levels, depending on variety, weather, culture and soil type. Strong signs of calcium deficiency usually occur on fruit ⅓ to ⅔ mature.

The first external symptom to appear is a small water-soaked spot at or near the blossom end (opposite the stem) of the pepper. The water-soaked spot eventually enlarges with time and becomes dry, sunken, flattened, brown or black, and papery or leathery. Secondary attack by fungal or bacterial organisms may cause fruit rots, but these are not the primary causal factors.

Although the necrotic tissue associated with this disorder is calcium deficient, the development of the disorder has more to do with water relations. Calcium moves passively in plants, primarily in the xylem in the transpiration stream. Once incorporated into plant tissues, calcium is relatively immobile in the plant. Very little calcium moves downward in phloem tissue.

Several factors contribute to the development of this disorder. Since calcium moves into roots through the unsuberized tips of root hairs, any damage that occurs to these cells can interfere with calcium uptake. This can be particularly problematic during periods of fruit development. Damage to root hairs can occur from insects, diseases or nematodes. Cultivation that damages the roots or dry soil conditions can also damage these root hairs. Extremely wet soils can also be a factor in blossom-end rot, but whether this results from excess water or damage to root hairs is unclear.

During periods of rapid transpiration, as occurs during very hot weather, calcium may rapidly move to and accumulate in the growing tips but not move to developing fruit. This increases the likelihood of blossom-end rot.

Other nutrients may affect calcium uptake and thus the occurrence of blossom-end rot as well. Ammonium forms of nitrogen may inhibit calcium uptake while nitrate forms may in-crease its uptake. Calcium uptake may also be inhibited by excess magnesium or potassium. Under low pH conditions (<5.0) calcium uptake may be inhibited by aluminum, which competes for uptake sites. Finally, boron can have a synergistic effect on calcium uptake, increasing calcium uptake.

Preventing blossom-end rot usually involves ensuring adequate calcium is available to the plant, but, more importantly, maintaining a uniformly moist soil throughout the growing season. Excessive drying or water logging seems to increase the likelihood of this disorder as do swings from extremes of wet and dry soils.

Minimize damage to the roots by controlling soilborne insects and diseases (see the respective sections elsewhere in this guide). Crop rotation may help reduce the incidence of soilborne insect and disease problems. Cultivation should be shallow to prevent damage to the roots.

Fruits that begin to show symptoms of the disorder cannot be cured, but exogenous applications of calcium to the plant can help prevent the disorder. Most importantly, proper calcium levels in the soil coupled with the correct pH as well as maintaining evenly moist conditions are the best ways to prevent the problem.

Pepper Stippling

Pepper stippling is a physiological disorder that is also associated with calcium deficiency. Small (0.25 inch) spots occur inside the fruit wall as the pepper reaches maturity. These spots are brown or black and result in green or yellow spots occurring on the fruit surface. Potassium deficiency may also play a role in this disorder.

Newer varieties are available that are resistant to this stippling. This is probably the best method of control. Although seed companies are only claiming resistance to stippling, these resistant varieties may be helpful in controlling blossom-end rot.

Sunscald

Sunscald occurs when ripening fruit is not adequately shaded by leaf cover. Large sections of the exposed fruit can develop gray or brown paper-thin areas. These areas render the fruit unsalable. Selecting varieties that produce sufficient leaf canopy, preventing diseases and insects that defoliate the plant, and maintaining adequate fertility, particularly after fruit set, are important considerations in controlling this problem.

Poor Color Development

This occurs when peppers don’t receive sufficient light into the canopy. This can be a particular problem when peppers are grown to full maturity and allowed to develop to colors beyond the initial green.

Nutrient and Other Disorders

Nutrient disorders beyond blossom-end rot can occur in peppers if fertilization is inadequate. Primary, secondary and micronutrient deficiencies and toxicities can occur but can be easily detected with soil testing, leaf tissue analysis or sap testing, and can be prevented or controlled with proper pH adjustment and proper fertilization (see section on fertilization).

Low soil pH can result in stunted plants that exhibit magnesium deficiency. Low pH can also contribute to toxicity from aluminum.

Toxicities can also occur due to applications of certain fungicides, particularly copper based materials, or due to non-target herbicide use that may be difficult to assess. Often this is due to material drift or improper waiting periods from applications to previous crops.

Lime and Fertilizer Management

W. Terry Kelley and George E. Boyhan, Extension Horticulturists
and Darbie M. Granberry, Retired Extension Horticulturist

Lime and fertilizer management should be tailored to apply optimal amounts of lime and nutrients at the most appropriate time(s) and by the most effective application method(s). Fertilizer management is impacted by cultural methods, tillage practices, and cropping sequences. A proper nutrient management program takes into account native soil fertility and residual fertilizer. Therefore, the first step in an appropriate fertilizer management program is to properly take a soil test 3 to 5 months before the crop is to be planted.

Soil pH

Adjusting the soil to the appropriate pH range is the first consideration for any fertilizer management program. The soil pH strongly influences plant growth, the availability of nutrients, and the activities of microorganisms in the soil. It is important to keep soil pH in the proper range in order to produce the best yields of high quality peppers. Soil tests results indicate soil pH levels and also provide recommendations for any amounts of lime required to raise the pH to the desired range.

The optimum pH range for pepper production is 6.2 to 6.8. Most Georgia soils will become strongly acid (pH 5.0 or less) with time if lime is not applied. Continuous cropping and application of high rates of nitrogen reduce pH at an even faster rate. In addition to raising pH, lime also adds calcium and, with dolomitic lime, magnesium to the soil.

The two most common liming materials available in Georgia are calcitic and dolomitic limestone. Dolomitic limestone also contains 6 to 12 percent magnesium in addition to calcium. Since many soils, particularly lighter Coastal Plains soils, routinely become deficient in magnesium, dolomitic limestone is usually the preferred liming material.

Calcium has limited mobility in soil, therefore lime should be broadcast and thoroughly incorporated to a depth of 6 to 8 inches. This will also neutralize soil acidity in the root zone. To allow adequate time for neutralization of soil acidity (raising the pH), apply and thoroughly incorporate lime 2 to 3 months before seeding or transplanting. If application cannot be made this early, liming will still be very beneficial if applied and incorporated at least 1 month prior to seeding or transplanting.

Fertilizer Management and Application

Recommending a specific fertilizer management program universally for all pepper fields would result in applications that are inefficient and not cost effective. 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 test analyses have the greatest potential for providing peppers with adequate but not excessive fertility. Applications limited to required amounts result in optimum growth and yield without wasting fertilizer, encouraging luxury consumption of nutrients, which can negatively impact quality, or causing fertilizer burn.

Recommendations based on soil tests and complimented with plant tissue analysis during the season should result in the most efficient lime and fertilizer management program possible. However, valid soil sampling procedures must be used to collect the samples submitted for analyses. To be beneficial, a soil sample must reliably represent the field or “management unit” from which it is taken. Soil samples that are improperly collected, compiled or labeled are of dubious benefit and may actually be detrimental. If there are questions about soil sampling, please contact your local county extension office for information.

In addition to lime application, preplant applications and in-season supplemental applications of fertilizer will be necessary for good crop growth and yield. In general, preplant applications are made prior to installation of plastic mulch. Research shows that broadcasting over the entire field is usually less effective than banding. An acceptable alternative to field broadcasting and one that is most often used with plastic mulch production, is the “modified broadcast” method, where the pre-plant fertilizer containing a portion of the nitrogen and potassium, and any recommended phosphorous and micronutrients, are broadcast in the bed area only. For example, on a 72-inch wide bed, a swath (24 inches to 48 inches wide) of fertilizer is uniformly applied centered over the bed and incorporated by rototilling. Additional applications are then made through the drip irrigation system. In bareground culture, pre-plant applications are followed by one to three sidedressed applications. The general crop requirements and application timings for the various nutrients are discussed below.

Starter Fertilizer Solution

Fertilizer materials that are dissolved in water and applied to the soil around plant roots at or just after transplanting are called starter solutions. When proper formulations and rates are applied, they can promote rapid root development and early plant growth. Starter solutions for pepper should contain a high rate of phosphorus (approximate ratio of 1 Nitrogen:3 Phosphorus:0 Potassium is common) and should be mixed and applied according to the manufacturer’s directions. Common starter solutions consist of 3 pounds of a formulated material (such as 10-34-0, which weighs approximately 11 lbs./gallon) mixed in 50 gallons of water. Approximately ½ pint of the starter solution is normally applied per plant. In addition to supplying phosphorus, which may be inadequately available (especially in cold soils in the early spring), the starter solution supplies water and firms the soil around roots. This helps eliminate air pockets that can cause root drying and subsequent plant or root damage. A starter solution is no substitute for adequate rainfall or irrigation after transplanting, however.

Be careful to mix and apply starter fertilizer according to the manufacturer’s recommendations. If the starter solution is too highly concentrated (mixed too strong), it 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 the tank becomes empty. This helps prevent the gradual increase in concentration that will occur if a portion of the previous mix is used for a portion of the water component in subsequent batches. If a dry or crystalline formulation is used, be sure it is thoroughly mixed and agitated in the tank, since settling can result in streaks of highly concentrated application that can stunt or kill plants as well.

Phosphorus and Potassium Recommendations

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

All the recommended phosphorus should be incorporated into the bed prior to plastic mulch installation or, for bare ground production, applied during or near transplanting. Approximately ½ pint of a starter solution, as described above, should be applied to each transplant. For bare ground production, around 100 to 150 pounds per acre of a pop-up fertilizer promotes earlier growth, particularly in cool/ cold soils. A good pop-up fertilizer is similar to or equal to 10-34-0. It should be relatively high in phosphorus and low in potassium. 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.

One-third to one-half of the potassium should either (1) be incorporated into the bed prior to installing plastic mulch, or (2) be applied in two bands, each located 2 to 3 inches to the side and 2 to 3 inches below the level of plant roots for bare ground production. The remainder of the recommended potassium should be applied through the drip system according to the schedule in Table 2 or, for bare ground culture, 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. The maximum number of applications is usually more effective on sandy soils.

Nitrogen Recommendations

Typical Coastal Plains soils require a total of 150 to 200 pounds of nitrogen (N) per acre. Extremely sandy soils may need additional N or an increased number of applications. Piedmont, Mountain and Limestone Valley soils usually require only 100 to 150 pounds of N per acre for pepper production.

N rates actually needed will vary depending on rainfall, soil type, soil temperature, irrigation, plant population, duration of the harvest season, and method and timing of applications.

For typical Coastal Plains soils, one-fourth to one-third of the recommended nitrogen should either (1) be incorporated into the bed prior to plastic installation or (2) with bare ground culture, applied in two bands, each located 2 to 3 inches to the side and 2 to 3 inches below the level of plant roots. Apply the remaining recommended N through drip irrigation according to the schedule in Table 2. On bare ground, one to three side-dressed applications (possibly four to five applications with extended harvest period on very sandy soil) are 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 to two applications are usually sufficient.

Approximately 50 percent of the total applied N should be in the nitrate form. High rates of ammoniacal nitrogen may interfere with calcium nutrition and result in an increased incidence of blossom-end rot (BER).

Side dressing or fertigating with calcium nitrate as the nitrogen source often significantly reduces the severity of BER.

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, apply 5 pounds of actual zinc per acre. These nutrients should be supplied in the pre-plant fertilizer application.

Foliar Application of Fertilizer

The fact that plants can absorb some 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 of a waxy cuticle. In some instances, plants that seem to benefit from foliar uptake are actually benefitting from nutrient spray that reaches the soil and is taken up by roots.

The effectiveness of applying macronutrients such as nitrogen, phosphorus and potassium to plant leaves is questionable. It is virtually impossible for pepper plants to absorb enough N, P or K through the leaves to fulfill their nutritional requirements; furthermore, it is unlikely that they could absorb sufficient amounts of macronutrients to correct major deficiencies. Although nitrogen may be absorbed within 24 hours after application, up to 4 days are required for potassium uptake and 7 to 15 days are required for phosphorus to be absorbed from foliar application.

The crucial question is whether or not 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 a proper soil applied fertilizer program is used, additional foliar fertilization is not usually required.

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

Quite often after frost or hail occurs, pepper growers apply foliar nutrients to give the plants a boost to promote rapid recovery. However, if a proper fertilizer program is being used before foliage damage, pepper plants don’t need additional fertilizer. What they do need is time and the proper environment for the normal recovery processes to occur. In addition, the likelihood of significant nutritional benefits from a foliar application of fertilizer to plants that have lost most of their leaves (or have a large proportion of their leaves severely damaged) is questionable.

Foliar application of sulfur, magnesium, calcium and micronutrients may help alleviate deficiencies. They should be applied, however, only if there is a real need for them and only in quantities recommended for foliar application. Application of excessive amounts can cause fertilizer burn and/or toxicity problems.

Foliar applications of calcium nitrate or calcium chloride (one to three weekly applications beginning at first bloom or at first sign of BER) may reduce the incidence of blossom-end rot (BER), but results are highly variable. The recommended rate is 3 to 4 pounds in 100 gallons of water per acre.

Two to three foliar applications of water soluble boron (approximately 1 to 2 ounces by weight of actual boron per application) at weekly intervals coinciding with flowering has, in some instances, enhanced fruit set. A commercial formulation that contains both boron and calcium (2 to 3 ounces by weight of calcium per application) may be applied. Follow manufacturer's directions when applying any commercial calcium/boron formulations.

Plant Tissue Analysis and Petiole Sap Analysis

Plant tissue analysis or petiole sap analysis is an excellent tool for measuring the nutrient status of the crop during the season. Particularly with fertigation, it is simple to adjust fertilizer injection rates according to the analysis results. Sufficiency ranges for tissue analysis are given in Table 3 and are for early bloom stage with the sample taken from the most recently mature leaf.

Fresh sap can be pressed from the petioles of pepper plants and used to determine nitrogen and potassium nutritional status. Sufficiency ranges for these are listed in Table 4.

Table 4. Sufficiency ranges for petiole sap tests for pepper at various stages of crop development.
Crop Development Stage	Fresh Petiole Sap Concentration
Crop Development Stage	NO₃-N	K
First Flower Buds	1400-1600	3200-3500
First Open Flowers	1400-1600	3000-3200
Fruits Half Grown	1200-1400	3000-3200
First Harvest	800-1000	2400-3000
Second Harvest	500-800	2000-2400

Sprayers

The equipment used for applying liquid insecticides, fungicides, herbicides and foliar fertilizers are classified as sprayers. Basically, there are two types of sprayers recommended for spraying peppers — hydraulic and air-curtain boom. The key to maximum coverage with insecticide and fungicides is the ability of the air within the plant canopy to be replaced with pesticides.

The air-curtain booms, or “air-blast sprayers” (Figure 1) are designed with an external blower fan system. The blower creates a high velocity of air that will “entrain” or direct the spray solution toward the target. Some sprayers provide a shield in front of or behind the conventional spray pattern, protecting the spray from being blown off-target.

The concept of this approach is to increase the effectiveness of pest-control substances, provide better coverage to the undersides of leaves, promote deeper penetration into the crop canopy, make it easier for small droplets to deposit on the target, cover more acres per load, and reduce drift.

Studies conducted by the U.S. Department of Agriculture Agricultural Research Service in Stoneville, Mississippi, have shown that the air-assisted sprayers tended to show improved insect control in the mid- to lower canopies. The air stream tended to open the canopy and help spray particles penetrate to a deeper level. Mid- to lower-canopy penetration and coverage is important when working with insecticides and fungicides but may not be as critical when applying herbicides.

The hydraulic boom sprayers (Figure 2) get their name from the arrangement of the conduit that carries the spray liquid to the nozzles. Booms or long arms on the sprayer extend across a given width to cover a particular swath as the sprayer passes over the field. Each component is important for efficient and effective application.

Most materials applied by a sprayer are a mixture or suspension. Uniform application demands a uniform tank mix. Most boom sprayers have a tank agitator to maintain uniform mixture. The agitation (mixing) may be produced by jet agitators, volume boosters (sometimes referred to as hydraulic agitators) or mechanical agitators. These can be purchased separately and put on sprayers. Make sure an agitator is on every sprayer. Some growers make the mistake of not operating the agitator when moving from field to field or when stopping for a few minutes. Agitate continuously when using pesticides that tend to settle out.

Nozzles

Nozzle tips are the most neglected and abused part of the sprayer. Since clogging can occur when spraying, clean and test nozzle tips and strainers before each application. When applying chemicals, maintain proper ground speed, boom height and operating pressure. This will ensure proper delivery of the recommended amount of pesticide to the plant canopy.

Herbicides

The type of nozzle used for applying herbicides is one that develops a large droplet and has no drift. The nozzles used for broadcast applications include the extended range flat fan, drift reduction flat fan, turbo flat fan, flooding fan, turbo flooding fan, turbo drop flat fan and wide angle cone nozzles. Operating pressures should be 20 to 30 psi for all except drift reduction and turbo drop flat fans, flooding and wide angle cones. Spray pressure more than 40 psi will create significant spray drift with flat fans nozzles. Drift reduction and turbo drop nozzles should be operated at 40 psi. Flooding fan and wide angle cone nozzles should be operated at 15 to 18 psi. These nozzles will achieve uniform application of the chemical if they are uniformly spaced along the boom. Flat fan nozzles should be overlapped 50 to 60 percent.

Insecticides and Fungicides

When applying insecticides and fungicides, use solid or hollow cone type nozzles. The two patterns that are developed by solid or hollow cone nozzles can be produced by different tip configurations. One type tip, disc-n-core, con-sists of two parts. One part is a core (swirl plate) where the fluid enters and is forced through tangential openings. Then a disc-type hardened stainless steel orifice (opening) is added. Another type of tip that produces the same patterns is of one-piece construction (nozzle body). In this type of tip, liquid is passed through a precision distributor with diagonal slots, which produce swirls in a converging chamber. The resulting pattern of both tip configurations is either solid or hollow cone. Even fan and hollow cone nozzles can be used for banding insecticide or fungicides over the row.

Nozzle Arrangement

When applying insecticides and fungicides, it is advantageous to completely cover both sides of all leaves with spray. When spraying peppers, use one or two nozzles over the top of the row (up to 8 inches wide). Then, as the plants start to grow and bush, adapt the nozzle arrangement for the various growth stages of plants (Figures 3 and 4).

Opposing nozzles should be rotated clockwise slightly so that spray cones do not collide. This will guarantee that the spray is applied from all directions into the canopy. As the plant increases in height, add additional nozzles for every 8 to 10 inches of growth. In all spray configurations, the nozzle tips should be 6 to 10 inches from the foliage. Properly selected nozzles should be able to apply 25 to 125 gallons per acre when operating at a pressure of 60 to 200 or higher psi. Usually, more than one size of nozzle will be needed to carry out a season-long spray program.

Calibration

Calibrate sprayers often. Calibration should be conducted every 8 to 10 hours of operation to ensure proper pesticide application. A good calibration procedure to follow is Calibration Method for Hydraulic Boom and Band Sprayers and Other Liquid Applicators, University of Georgia Extension Circular 683. This circular is available through local county extension offices and on the web at: http://pubs.caes.uga.edu/caespubs/pubcd/C683.htm

Diseases

Plant diseases are one of the most significant limiting factors to pepper production in Georgia. The hot, humid climate coupled with frequent rainfall and mild winters favor the development of many pathogens and the diseases they cause.

Bacterial Diseases

Bacterial spot is the most common and often the most serious disease affecting peppers in Georgia. This disease is caused by the bacterium Xanthomonas campestris pv. vesicatoria. Bacterial spot lesions can be observed on leaves stems and fruit, and occurs on all stages of plant growth. Leaf lesions usually begin as small, water-soaked lesions that gradually become necrotic and brown in the center (Figure 5). During wet periods the lesions appear more water-soaked. Lesions generally appear sunken on the upper surface and raised on the lower surface of infected leaves. During periods of favorable weather, spots can coalesce and cause large areas of chlorosis (Figure 6). Premature leaf drop is the ultimate result of leaf infection. Fruit lesions appear as small, round, dark brown to black spots.

The bacterium is primarily seed-borne, and most epidemics can be traced back, directly or indirectly, to an infected seed source. Infected seedlings carry the disease to the field where it spreads rapidly during warm, wet weather. Workers working in wet fields can also be a major source of disease spread.

All pepper seed planted for transplants or direct seeded field grown peppers should be tested by a reputable seed testing company. Transplants should be inspected for bacterial spot lesions before being sold or planted in the field.

Prevention is the best method for suppressing losses to bacterial spot. Purchase seed from companies that produce the seed in areas where the disease is not known to occur. Hot water seed treatment can also be used and pepper seed can be soaked in water that is 125 degrees F for 30 minutes to kill the bacterium.

Transplant production should take place in areas away from commercial production so as to avoid contamination from production fields or vice versa. Use of resistant varieties is the next line of defense and most commercial varieties have resistance to some of the known races of bacterial spot. Rotate away from fields where pepper has been grown within the past year and use practices that destroy volunteers that could allow the disease to be carried over to a subsequent crop.

Cull piles should be away from production fields or transplant houses. Copper fungicides used in conjunction with maneb will suppress disease losses if applied on a preventive schedule with a sprayer that gives adequate coverage.

Virus Diseases

Virus diseases have been a severe limiting factor in pepper production in Georgia for several years. Most virus diseases cause stunting, leaf distortion, mosaic leaf discoloration, and spots or discoloration on fruit. The dissemination of virus-infected plants is usually random with symptomatic plants often bordered on either side by healthy, non-symptomatic plants. Virus diseases are almost always transmitted by insect vectors, and the severity of a virus disease is usually tied to the rise and fall in the populations of these vectors from season to season and within a given season. However, some virus diseases are seed and mechanically transmitted. Only the viruses that have been the most problematic on pepper in Georgia will be covered in this section.

Tomato spotted wilt virus (TSWV) is one of the most common viruses affecting pepper in the southeastern United States. This virus is transmitted by thrips and can affect pepper at any stage of development. The extensive host range of TSWV in weeds allows for a continual source of inoculum for infection. However, as with any virus disease, early infections tend to cause more yield losses than those occurring later in plant development. TSWV causes plant stunting, rosetted leaves, ringspots (Figure 7), mottling, mosaic, bronzing and terminal necrosis on infected plants.

Pepper fruit produced on infected plants may be misshapen, have raised ringspots (Figure 8), or have small black specks (Figure 9). TSWV in Georgia pepper has been suppressed through the use of black plastic and other colored mulches, particularly reflective mulches, as well as with resistant varieties.

Cucumber mosaic virus (CMV) is a very common disease of pepper and can be very devastating where it occurs. This virus is transmitted by aphids and can be maintained in several weed species that surround production fields. Symptoms of CMV are very variable and range from almost no symptoms to severe stunting and mottling, and necrosis of foliage. In some instances, fruit produced on infected plants will be distorted and begin to break down on the distal end (blossom end) of the fruit, particularly in the seams that separate the capsules (Figure 10). However, some fruit have only mild discoloration and distortion.

Pepper varieties that are resistant to CMV have been described and would be very useful, however commercially acceptable varieties for Georgia growers have not been made available. Use of reflective mulches may help reduce aphid transmission as will reduction of the weed reservoir surrounding fields.

Pepper mild mottle virus (PMMV) is a virus that has only recently caused losses in several pepper types in Georgia. This virus is primarily seedborne and spreads through the field mechanically by workers. Symptoms on foliage have been rather mild but a chlorotic mosaic pattern has been observed in some instances. Symptoms on fruit have been more predominant in Georgia and appear as irregular, sunken, discolored areas (Figure11). Control of PMMV is best achieved through the use of non-infected seed.

Fungal Diseases

Cercospora leaf spot caused by Cercospora capsici. This disease is somewhat rare in Georgia but has been reported throughout the southeast. Symptoms appear as small, round to oblong lesions with light gray centers on the leaves, stalks and leaf stems (Figure12). A dark border on the inside margin of the lesion is often observed. Infected leaves generally shed prematurely. The disease may be seed-borne, and infection may be traced to infected seedlings grown from contaminated seed. The disease can also be carried over on crop debris. Wet, humid weather favors disease development. In the field the fungus spores are spread mainly by wind. Unless controlled, it causes severe defoliation. The disease is easily controlled with chemical sprays. Spray programs used for bacterial leafspot and anthracnose will suppress Cercospora leaf spot.

Anthracnose caused by Colletotrichum acutaum and gloeosporioides. Both of these fungi cause diseases primarily on fruit with C. gloeosporioides causing disease on ripe fruit and C. acutatum causing disease on both immature and ripe fruit. Lesions are usually round and sunken and can be over an inch in diameter depending on the size of the fruit. Initially, lesions will contain a small area of tan to pink sporulation near the center (Figure 13). Older lesions contain concentric rings of pink or salmon colored conidial sporulation. In Georgia, C. acutatum has recently been shown associated with the more serious outbreaks. Anthracnose can be introduced to a field through contaminated seed or be sustained in infested plant debris. This disease is favored by warm, wet, humid weather. This disease is best controlled by using disease-free seed and rotating away from fields with a known history of losses to anthracnose. Preventive fungicide applications are also recommended.

Phytophthora fruit and crown rot caused by Phytopthora capsici. Phytopthora is a fungal-like organism that is in a separate kingdom than the fungi. It is a water-mold, oomycete organism that has a mobile swimming-spore stage as part of its life cycle. This particular disease is one of the most common and arguably the most destructive disease of pepper in Georgia, rivaled only by bacterial spot and TSWV in order of importance and yearly yield losses. Symptoms of Phytophthora fruit and crown rot are usually dead or wilted plants that begin dying in the section of the field that is most poorly drained. The crown region of the plant near the base is usually darkened, sunken and necrotic (Figure 14).

Figure 14. Pepper plant with Phytophthora crown rot.

Vascular discoloration can be observed in tissues above the ground. The disease generally spreads to other areas of the field through moving water (either irrigation or rain), equipment or workers. The foliar and fruit phase of the disease is rarely observed in Georgia. Control of Phytophthora fruit and crown rot is achieved by avoiding fields with a history of the disease, both in pepper and other crops.

If ponds are used for irrigation, they may be contaminated with the disease and should be identified and avoided. Resistant varieties have recently been made available that show good to fair resistance to this disease. Fungicide applications have been recommended and do show some benefits but fungicide resistance problems coupled with the subterranean nature of the organism hinder consistent performance of preventive or remedial fungicide treatments.

Southern stem rot caused by Sclerotium rolfsii. This is a common destructive disease of peppers in Georgia. Since many peppers are rotated with peanuts, soybeans and other susceptible crops, the disease has become a major problem. The fungus attacks the stem of the plants near or at the soil line and forms a white mold on the stem base. Later in the season, small, round brown bodies appear in the mold (Figure 15). Infected plants wilt and slowly die. Vascular discoloration can be observed in stem tissues above the lesion. The severity of this disease can be lessened by following good cultural practices: rotation, litter destruction and deep turning with a moldboard plow are the best cultural defenses against this disease. Fumigation as well as at-plant and drip-applied fungicides are also effective in reducing losses to southern stem rot.

Nematodes

Root-knot nematodes (Meloidogyne spp.) can cause serious economic damage to peppers. These tiny worms live in the soil and feed on the roots of peppers. Not only do they cause physical damage that interferes with the uptake of water and nutrients, but they allow the establishment of other diseases. Nematode infected plants are generally stunted with pale green to light yellow foliage. Symptoms may be temporarily masked by supplying additional fertilizer and water. Soils infested with root-knot nematodes should be avoided or treated with fumigant or chemical nematicides before peppers are planted.

Insect Management

While many insects that feed on pepper are only occasional pests in Georgia, a few species are common pests and occur annually. Insect pests can damage pepper throughout the growing season, but severity varies with location and time of year. The severity of damage to pepper by insect pests is largely due to abundance of the pests, which is related to environmental conditions. While we may be able to predict the potential for pest outbreaks, it is difficult to predict whether control measures will be required for most pest. For example, we know that caterpillar pests, whiteflies and broad mites h

Phosphorus and Potassium Recommendations
Phosphorus Ratings	Low	Medium	High	Very High
Recommended P	120	80	40	0
Potassium Ratings	Low	Medium	High	Very High
Recommended K	120	90	60	30
P - Represents pounds of P2O5 recommended per acre; K - Represents pounds of K₂O recommended per acre.
Note: If soil testing is done by a lab other than the University of Georgia Soils Testing Laboratory, the levels recommended above may not apply.

Table 2. An example fertilizer injection schedule for a Coastal Plains soil that is very low in potassium. The schedule is for a typical 14-week crop. Extended harvests will require additional injection applications.
Nutrient	Total	Preplant	Crop State in Weeks (lbs/A/day)
	(lbs/A)	(lbs/A)	1-2	3-4	5-6	7-10	11-12	13-14
Nitrogen	225	50	1.0	1.5	2.0	2.5	2.0	1.5
Potassium	175	0	1.0	1.5	2.0	2.5	2.0	1.5

Table 3. Plant tissue analysis ranges for various elements for pepper sampled at the early bloom stage with most recently mature leaves.
	N	P	K	Ca	Mg	S	Fe	Mn	Zn	B	Cu	Mo
Status	Percent						Parts per Million
Deficient	<3	0.3	2.5	0.6	0.3	0.3	30	30	25	20	5	0.2
Adequate	3-5	0.3-0.5	2.5-5	0.6-1.5	0.3-0.5	0.3-0.6	30-150	30-100	25-80	20-50	5-10	0.2-0.8
High	>5	0.5	5	1.5	0.5	0.6	150	100	80	50	10	0.8

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Figure 1. Air-assisted boom sprayer.		Figure 2. Hydraulic boom sprayer.

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Figure 5. Bacterial spot lesions on a pepper leaf.		Figure 6. Leaf chlorosis caused by bacterial spot.

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Figure 8. TSWV raised ringspots on pepper fruit.		Figure 9. TSWV black specks on pepper fruit.