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

Tomatoes are an important crop for Georgia growers; however, successful tomato production is not easily achieved. Tomato 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. Tomato 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 tomato production. However, chemical pest control recommendations are not included, as these change from year to year. For up-to-date chemical recommendations, see the current Georgia Pest Management Handbook.

History, Significance, Classification and Growth

The tomato (Lycopersicon esculentum Mill.) is the most widely grown vegetable in the United States. Almost everyone who has a garden has at least one tomato plant. They can even be produced in window box gardens or in single pots. Commercially, it is of equally great importance. From processing to fresh market, and from beefsteak to grape tomatoes, the variety and usefulness of the fruit is virtually boundless.

Tomatoes are members of the Solanaceae family, which includes peppers, eggplant, Irish potatoes and tobacco. The tomato originated in the area extending from Equador to Chile in the western coastal plain of South America. The tomato was first domesticated in Mexico where a variety of sizes and colors were selected. The fruit was introduced to Europe in the mid-1500s. The first ones introduced there were probably yellow since they were given the name pomodoro in Italy, which means “golden apple.” Later the names poma armoris and pomme d’amour were used in Italy and France. These names are both translated as “love apple.”

Tomatoes are members of the nightshade family and, because of this, were considered for many years to be poisonous. Indeed, many crops in this family contain highly toxic alkaloids. Tomatine occurs in toxic quantities in the tomato foliage but is converted enzymatically to a non-toxic form in the fruit. Because of these beliefs, the crop was not used for food until the 18^th century in England and France. Tomato was introduced to the United States in 1910, but only became popular as a food item later in that century. Even as late as 1900, many people held the belief that tomatoes were unsafe to eat.

Use of the crop has expanded rapidly over the past 100 years. Today more than 400,000 acres of tomatoes are produced in the United States. The yearly production exceeds 14 million tons (12.7 million metric tons), of which more than 12 million tons are processed into various products such as soup, catsup, sauce, salsa and prepared foods. Another 1.8 million tons are produced for the fresh market. Global production exceeds 70 million metric tons. Tomatoes are the leading processing vegetable crop in the United States.

California is the leading producer of processing tomatoes in the United States. Indiana, Michigan and Ohio are other major producers. California and Florida are the leading fresh market tomato producers in the United States. Ohio, Tennessee, Virginia and Georgia produce significant amounts of fresh market tomatoes as well.

Tomatoes have significant nutritional value. In recent years, they have become known as an important source of lycopene, which is a powerful antioxidant that acts as an anticarcinogen. They also provide vitamins and minerals. One medium ripe tomato (~145 grams) can provide up to 40 percent of the Recommended Daily Allowance of Vitamin C and 20 percent of Vitamin A. They also contribute B vitamins, potassium, iron and calcium to the diet.

There are two types of tomatoes commonly grown. Most commercial varieties are determinate. These “bushy” types have a defined period of flowering and fruit development. Most heirloom garden varieties and greenhouse tomatoes are indeterminate, which means they produce flowers and fruit throughout the life of the plant.

Tomato is considered a tender warm season crop but is actually a perennial plant, although it is cultivated as an annual. It is sensitive to frost and will not grow perpetually outdoors in most parts of the country. Most cultivated tomatoes require around 75 days from transplanting to first harvest and can be harvested for several weeks before production declines. Ideal temperatures for tomato growth are 70-85 degrees F during the day and 65-70 degrees F at night. Significantly higher or lower temperatures can have negative effects on fruit set and quality. The tomato is a self-pollinating plant and, outdoors, can be effectively pollinated by wind currents.

Culture and Varieties

Soil Requirements and Site Preparation

Tomatoes can be produced on a variety of soil types. They grow optimally 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 3-4 years. Select sites that have good air movement (to reduce disease) and that are free from problem weeds.

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

For tomato 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 tomato 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. Tomatoes are considered to be deep rooted and, under favorable conditions, some roots will grow to a depth of as much as 10 feet. The majority of roots, however, 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” or “turning”) plow prepare the greatest soil volume conducive to vigorous root growth. This allows the development of more extensive root systems, 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 are normally located at or just below plow depths. Although compaction pans may be only a few inches thick, their inhibitory effects on root growth can significantly reduce tomato 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. This should be done 6 to 8 weeks ahead of planting to bury residue and allow it to decay. Immediately prior to plastic mulch installation or transplanting, perform 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.

Tomatoes are usually transplanted into plastic mulch on raised beds. A raised bed will warm up more quickly in the spring and therefore will enhance earlier growth. Since tomatoes do poorly in excessively wet soils, a raised bed facilitates drainage and helps prevent waterlogging in low areas or in poorly drained soils. Raised beds are generally 3 to 8 inches high. Keep in mind, however, that tomatoes 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 animal residues in various stages of decay. Organic matter improves soil structure (helps to reduce compaction and crusting), increases water infiltration, decreases water and wind erosion, increases the soil’s ability to resist leaching of many plant nutrients, and releases plant nutrients during decomposition.

The planting of cover crops and subsequent incorporation of the green manure into the soil enhances tomato production in Coastal Plains soils. Wheat, oats, rye or ryegrass can be used 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 4 to 6 weeks prior to installing mulch or transplanting tomatoes.

Planting tomatoes in reduced tillage situations has been tried with variable results in different parts of the country. Often cover crops can be killed with a burn down herbicide. Then tomatoes are either transplanted directly into the cover, or a narrow strip is tilled and prepared for transplanting while leaving the residue between rows. While these residues can protect the fruit from direct contact with the soil, currently the impediments outweigh the benefits for large-scale commercial production. Leguminous covers can provide nitrogen to the crop and there are certainly soil conservation advantages.

The primary encumbrance to success in reduced tillage systems is adequate weed and disease control. The application of phosphates, potash and lime are also more difficult in these systems, so reduced tillage is used only on a limited basis in commercial tomato production. With advances in weed and disease control technology, this type of production may become more feasible in the future.

Windbreaks

Crop windbreaks can aid in crop protection and enhance early growth and yield. Frequency or intervals between windbreaks is dictated by distance between tomato 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. Plant windbreaks perpendicular to the prevailing wind direction. When using a taller growing windbreak such as rye, you can expect the windbreak to be effective to a width of about 10 times its height. For instance, with a rye crop that is 3 feet high, the windbreaks can be effective up to 30 feet apart.

In general, close windbreaks give the best wind protection and help moderate the tomato plants’ microenvironment and enhance earliness. Especially on sandy soils, windbreaks reduce damage from sandblasting of plants and small fruit during early spring. Sandblasting can be more of a problem with plastic mulch, as the soil particles are carried easily by the wind across the field. Many growers spread small grain seed after the plastic mulch is applied to reduce sand blasting. Windbreaks also conserve soil moisture by reducing direct evaporation from the soil and transpiration from the plant. This can enhance plant growth throughout the season.

Regardless of the species selected to be used as a windbreak, plant it early enough to be effective as a windbreak by the time tomatoes are transplanted. Establishment of a windbreak crop during the fall or early winter should ensure enough growth for an effective windbreak by spring tomato planting time. Wheat, oats or rye all make good windbreak crops. Windbreaks can be living or non-living. Tomato beds can be established between the windbreaks by tilling only in the bed area.

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

Transplanting

Seeding tomatoes directly into the field is not recommended due to the high cost of hybrid seed and the specific conditions required for adequate germination. Most tomatoes are transplanted to the field from greenhouse-grown plants. Direct seeding has other disadvantages: (1) Weed control is usually much more difficult with direct seeded than with transplanted tomatoes; (2) direct seeding requires especially well made seedbeds and specialized planting equipment to adequately control depth of planting and in-row spacing; (3) because of the shallow planting depth required for tomato seed, the field must be nearly level to prevent seeds from being washed away or covered too deeply with water-transported soil; and (4) spring harvest dates will be at least 2 to 3 weeks later for direct seeded tomatoes.

At 59, 68 and 77 degrees F soil temperature, tomato seed require 14, 8 and 6 days, respectively, for emergence when planted ½ inch deep.

Typically, 5- to 6-week old tomato 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) usually require little, if any, replanting, (3) resume growth more quickly after transplanting, and (4) grow and produce more uniformly. Tomato plants produced in a 1-inch cell size tray are commonly used for transplanting. Many growers will use a 1.5-inch cell tray for transplant production in the fall when transplant stress is greater.

Tomato transplants should be hardened off before transplanting to 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 for a short period prior to taking the plants to the field. Research shows that reducing temperatures too drastically to harden tomato transplants can induce catfacing in the fruit.

For maximum production, transplants should never have fruits, flowers or flower buds before transplanting. An ideal transplant is young (6 inches to 8 inches tall with a stem approximately ¼ inch to ⅜ 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 development. In most cases, it is more economically feasible to have transplants produced by a commercial transplant grower than to grow them on the farm. When purchasing transplants, be sure the plants have the variety name, have been inspected and approved by a plant inspector, and they are of the size and quality specified in the order.

Set transplants as soon as possible after removing from containers or after pulling. If it is necessary to hold tomato plants for several days before transplanting them, 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 them upright and place the roots 3 to 4 inches deep. Setting plants at least as deep as the cotyledons has been shown to enhance plant growth and early fruit production and maturity. Completely cover the root ball with soil to prevent wicking moisture from the soil. Tomatoes grow best if nighttime soil temperatures average higher than 60 degrees F.

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

Plant Spacing

Tomatoes can be planted in one of many different arrangements that provide adequate space for plant growth. Often the spacing is based on the type of trellising and equipment that will be used in the field. The within-row and between-row spacings are selected to meet these limitations. The optimal plant population per acre may also be influenced by plant growth habit (compact, spreading), plant size at maturity (small, medium, large), vigor of specific cultivars, climate, soil moisture, nutrient availability, management system and soil productivity.

Generally, for production of determinate varieties on plastic mulch, a minimum of 5 feet between rows is used with an in-row spacing of 18 to 24 inches. Six feet between rows is also a popular interval. To space plants 22 inches apart in rows that are 5 feet apart requires 4,760 plants per acre. With 6-foot centers and 18 inches between plants, 4,840 plants are required per acre. Usually a single row of tomatoes is planted down the center of each plastic mulched bed.

On bare ground, space rows 48 to 72 inches apart with 18 inches to 24 inches between plants in the row. For indeterminate types of tomatoes, which produce larger plants, adjust spacing to decrease the population accordingly.

Varieties

Select varieties on the basis of marketable yield potential, quality, market acceptability, adaptability and disease resistance or tolerance. The selection of a variety(ies) should be made with input from the buyer of the crop several months in advance of planting. Other characteristics to consider include maturity, size, shape, color, firmness, shipping quality and plant habit.

There are a plethora of commercially available tomato varieties, many of which will perform well under Georgia conditions. Varieties will perform differently under various environmental conditions. Yield, though ultimately important, should not be the only selection criteria. Tomatoes produced on plastic mulch with drip irrigation will commonly average more than 1,500 25-pound cartons per acre. Select varieties that have yield potential that equals or surpasses this average.

Plants also need to produce adequate foliage to protect fruit. Basically, a variety must be adaptable to the area, produce a competitive yield and be acceptable to buyers. Disease resistance will be most important with diseases for which there are no other good management options. Varieties produced in Georgia should be resistant to Fusarium wilt (Races 1 and 2) and Verticillium wilt (Race 1). In recent years, resistance to Tomato Spotted Wilt Virus has become equally as important, since varietal resistance is the most effective control method at this time. Other resistance of significance should include Gray Leaf Spot and Tobacco Mosaic Virus.

All commercially important tomatoes grown in Georgia belong to the species Lycopersicon esculentum. Table 1 lists those 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. Tomato varieties that have exhibited acceptable performance either in variety trials or in grower fields in Georgia.
Variety	Days to Maturity	Fruit Size	Shape	Disease Resistance
Large Round
Amelia	78	L, XL	Oblate	F¹²³, ST, TSWV, V, FCR
BHN 444	80	L, XL	Globe	F¹², TSWV, V
BHN 640	80	L, XL	Globe	F¹²³, TSWV, V
Biltmore (trial)	80	L	Deep Oblate	F¹², ST, ASC, V
Carolina Gold	78	L, XL	Deep Oblate	F¹², V
Crista	78	XL, L	Round	F¹²³, TSWV, V
Florida 47 R	75	VL	Deep Oblate	F¹², GLS, ASC, V
Florida 91*	72	L	Deep Oblate	F¹², GLS, ASC, V
Mountain Crest	75	XL, L	Flat-Globe	F¹², V, FCR
Mountain Spring	78	XL	Deep Oblate	F¹², St, V, FCR
Sebring	75	XL, L	Deep Oblate	F¹²³, ST, FCR, V
Solar Fire*	75	L	Flat-Round	F¹²³, ST, V
Solar Set*	75	M, L	Flat-Round	F¹², ASC, GLS, V
Solimar	78	L	Globe	F¹², ASC, GLS, V
Talladega (trial)	78	XL, L	Globe	F¹², TSWV, V
Tygress (trial)	78	L	Deep Oblate	F¹², V, GLS, TYLC
Cherry
Cherry Grande	65	Cherry	Globe	F¹, ST, ASC, V
Mountain Belle	68	Cherry	Round-Oval	F¹, V
Roma/Saladette
BHN 685	75	Roma	Blocky Globe	F¹²³, TSWV, V
Plum Crimson	75	L, XL	Saladette	F¹²³, V
Plum Daddy	75	Roma	Elongated Roma	F¹, V
Puebla	72	M	Elongated Cyl.	F¹², ST, ASC, V, BS
F = Fusarium Wilt; ST = Stemphylium; TSWV = Tomato Spotted Wilt Virus; V = Verticillium Wilt; FCR = Fruit Cracking; ASC = Ascomycetes; GLS = Gray Leaf Spot, BS = Bacterial Spot; TYLC = Tomato Yellow Leaf Curl * hot-set varieties.

Staking and Pruning

Most commercial determinate tomatoes are produced using short stake culture for trellising. This type of culture produces fruits that are higher in quality and easier to harvest and enhances spray coverage. In this system, stakes approximately 4 feet long and ¾ to 1 inch square are placed between every one or two plants depending on the tying system that is employed. Stakes are usually driven about 12 inches into the ground. An additional stake can be supplied at the ends of each section to strengthen the trellis.

Stake plants immediately after planting to minimize damage to the root system and to have the trellis ready when needed. Plants are usually tied initially when they are about 12-15 inches tall and should be tied prior to any plants lodging. The first string is usually placed about 10 inches above the ground. Subsequent tyings are placed about 6 inches above the previous one. Determinate varieties may be tied as many as three to four times.

The Florida weave system is one method of tying that is often used. In this system, a stake is placed between every other plant in the row. Twine is then used to tie the plants using a figure eight weave. The twine is wrapped around the stake and is pulled tightly on one side of the first plant and then between the two plants and along the other side of the second plant. At the end of the row or section, the pattern is reversed and, as the twine is wrapped around each stake, the twine is then placed on the other side of each plant going back in the opposite direction along the row. This system uses fewer stakes and encloses the plant with the twine. Subsequent tyings often do not weave between plants but simply go along one side of the plants going one way and the opposite side going the other direction.

Another system of tying involves placing a stake after every plant. The twine is then simply wrapped around each stake and along one side of the plant going along the row and around the other side of the plant coming back in the other direction on the opposite side of the row. Regardless of the system used, the twine should be held with enough tension to adequately support the plants. If the twine is too tight, however, it can impede harvest and damage plants and fruit.

Tomato twine should be resistant to weathering and stretching and should not cut into the plants or fruit. It takes about 30 pounds of synthetic twine per acre for tomatoes. A simple tying tool can be made from conduit or PVC pipe that is 2 to 3 feet long. The twine is passed through the pipe to act as an extension of the worker’s arm. This limits the need to stoop over at each stake to wrap the twine. A similar tool can be made from a wooden dowel or narrow wooden strip. With these, a hole is drilled about 1 inch from each end of the piece of wood and the string passed through each hole. This provides the same extension of the hand as the other method.

Determinate tomatoes often still require some level of pruning. Pruning is the removal of suckers (axillary shoots). The degree to which pruning is needed will vary with the variety used but can impact yield and quality significantly. Plants that produce vigorous foliage that are not pruned will produce more, but smaller fruit. Pruning helps increase the size of the fruit. It can also enhance earliness of the crown set, reduce pest pressure and enhance spray coverage. In general, pruning will involve removal of one to all suckers up to the first fork (the sucker just below the first flower cluster).

Growers should experiment with individual varieties to determine the degree of pruning needed. Often the seed supplier can provide information on specific varieties regarding pruning. Some varieties require only the removal of ground suckers (at the cotyledons) or none at all. Overpruning can cause reduced yields and increased sunburn, blossom end rot and catfacing. More vigorous varieties may require the removal of ground suckers plus two additional suckers. Remove suckers when they are small (2 to 4 inches long). Removal of large suckers is more time consuming and can damage the plant. Prune before the first stringing to facilitate the process, since the strings may be in the way. A second pruning may be required to remove suckers that were not large enough to remove easily during the first pruning and to remove ground suckers that may have developed. Prune plants when the foliage is dry to reduce the spread of disease.

Transplant Production

Tomato production in Georgia is an expensive, labor intensive endeavor developed to produce high quality fresh market fruit. Because of the cost involved and because early market fruit command higher prices, growers exclusively use transplants to produce tomatoes. Tomato transplant production is a relatively easy but highly specialized function of production. Many growers have neither the greenhouse facilities nor the expertise to undertake transplant production; instead, they will rely on greenhouse growers to produce their transplants. For these growers to ensure a quality supply of transplants, they should contract early with their greenhouse grower to secure plants of the variet(ies) they wish to grow.

Growers should expect to plant between 3,600 and 5,800 plants per acre in a staked tomato operation, depending on the plant spacing. Expect to produce about 4,000 transplants per ounce of seed with approximately 3 ounces required to produce 10,000 seedlings. For example, to produce 10 acres of tomatoes with 5,800 plants per acre would require 58,000 transplants and would require about 18 ounces of seed (rounding up to 60,000 plants). Many seed companies no longer sell seed by weight but by count and will supply the germination rate as well. In such a case, the count and germination rate can be used to estimate the amount of seed to plant to produce the desired number of plants. For example, to produce 58,000 seedlings from seed with 90 percent germination would require 64,445 seed (58,000 divided by 0.90).

Tomato seedlings are usually produced in trays or flats that are divided into cells. Tomatoes require a cell size of approximately 1 inch square to produce a high quality, easily handled transplant. These trays or flats are available in a number of different configurations and sizes. They may be purchased as flats and inserts, polystyrene trays or, more recently, as one-piece rigid polyethylene plastic trays. Growers should make sure the trays or flats used can be handled with their transplanting equipment.

Media for production is usually peat based with various additives such as perlite and vermiculite to improve its characteristics. These can be purchased ready mixed or you can formulate your own mix. The individual components of peat moss, perlite, vermiculite, etc., can be purchased. Whether buying the individual components or a ready-made product, it is advisable to use finer textured media when starting seed. Check with your supplier about media texture. Some media are specially made for this purpose. In addition, these media may have fertilizer and wetting agents mixed in. Media with fertilizer is often referred to as charged.

Treated and/or coated seed may be used to produce seedlings. Most seed is sold with a fungicide applied to the seed. This will help prevent damping off during the germination process. In addition, various seed coats are available, from polymer to clay coats. These are useful when using automated seeding equipment to aid in seed singulation. Plant tomato seed ⅛ to ¼ inch deep. With an automated seeder, the seed will be placed on the surface and will have to be covered, usually with a thin layer of vermiculite.

After flats have been filled and the seed planted, they are often wrapped with plastic pallet wrap or placed in germination rooms (rooms with temperature and humidity tightly controlled) for 48-72 hours to ensure even moisture and temperature for optimum germination. The optimum germination temperature for tomatoes is 85 degrees F, at which tomato seedlings should emerge in about 5-6 days. See Table 2 for soil temperatures and number of days to germination.

If charged media is used, there will be no need for fertilizer for the first 3 to 4 weeks of production. After that, use 150-200 ppm of a suitable water soluble fertilizer once per week (Table 3). With media that has no premixed fertilizer, begin fertilization as soon as the plants emerge. Growers may wish to use as little as 50 ppm of a suitable water soluble fertilizer with every irrigation. Tomatoes will require approximately 5 to 7 weeks to produce a good quality transplant. Cooler temperatures will slow growth, so greenhouse temperatures should be kept above 60 degrees F at night to accelerate growth.

Prior to transplanting, tomatoes should be hardened off. This is the process of reducing water and/or lowering temperature. Do this several days prior to transplanting. A good way to achieve this is to move the plants outside the greenhouse to a protected location (some shade), or open the sides of the greenhouse if possible. Reduce the amount of water the plants receive, but don’t allow the plants to wilt. Hardening plants is critically important to ensure survivability. Unhardened plants are much more vulnerable to environmental extremes.

A good quality transplant will be a sturdy, compact plant with a root mass that completely fills the cell. Water plants prior to transplanting. Tomatoes can be transplanted deeper than they grew in the greenhouse container and, in fact, it is desirable to do so. Roots will form on the stem that is below the ground.

Take care when transplanting into black plastic so the plants do not touch the plastic. The plastic can absorb enough heat to injure and kill plants. A drench of about 0.5 pint of a suitable starter solution should be applied to each plant. Examples of suitable solutions include mixing 3 pounds of 11-34-0 or 18-46-0 fertilizer in 50 gallons of water. Most transplanting equipment will have a tank to hold the solution and will automatically dispense the solution to each plant.

Carefully monitor plants for the first few days to a week after transplanting to ensure survival. Note any problems with dry soil, clogged irrigation, plants touching the plastic, etc., and take corrective action.

Production Using Plastic Mulch

The use of plastic mulch in the commercial production of staked tomatoes is almost universal in the south-east. Plastic mulch is used to promote earliness, reduce weed pressure, and to 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 tomato 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 particularly, disease is often reduced as the foliage stays drier and, again, soil is not splashed onto the plant.

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 and disposal 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 traditionally has been most often used in spring tomato production. Embossed plastic has a crimped pattern in the plastic that allows the mulch to stretch and contract so it can be laid snug to the bed. This can be important, particularly in multiple cropping operations where, for example, spring tomatoes may be followed by fall cucumbers. The embossed plastic is less likely to be damaged by wind and other environmental factors, thus increasing the potential for use on multiple crops.

Summer planted tomato 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 warm the soil as much. For spring production, however, white is not recommended since maximum soil warming is needed. In lieu of using white plastic, many growers use a dilute white paint sprayed over the bed to lighten the plastic and reflect heat for fall production.

Recently, metalized mulches have become popular. These plastic mulches have a thin film of metal that is applied with a vacuum which produces a reflective effect. Research has shown that these mulches can help reduce the incidence of Tomato Spotted Wilt Virus infection on tomatoes by repelling thrips. However, these mulches do not warm the soil as well as black mulches, resulting in reduced plant growth early in the spring. 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. Recent research has also shown that metalized mulches also retain fumigants better and may allow for use of reduced rates.

Virtually Impermeable Films (VIF) are used in some parts of the world to reduce fumigant release into the atmosphere. These films are as yet not 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 get 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. Mulch must be covered 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, which compromises the integrity of the plastic and reduces its effectiveness in controlling weeds and minimizing leaching of nutrients.

Land preparation for laying plastic is similar to that described in the prior chapter on culture and varieties. 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. The bed pan should leave a bed with a slight crown in the middle that slopes slightly to each side. This prevents water from standing on the plastic or being funneled into the holes and waterlogging the soil. 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 to the tape. Drip tape buried deeper will be difficult to remove and will not wet the upper portion of the root zone. 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), it is advisable to incorporate all phosphorus and micronutrients into the bed before installing plastic. If drip fertigation is not used, apply all the nitrogen and potassium preplant as well.

If narrower beds are used, preplant application of all the needed fertilizer may cause fertilizer salt toxicity. Sidedressing is required, therefore, by a liquid injection wheel, through drip irrigation, or a banded application outside the tucked portion of the bed.

Most tomatoes are planted where fertigation with drip irrigation is used. In these cases all the phosphorous (P) and micronutrients, and one-third to one-half of the nitrogen (N) and potassium (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. See University of Georgia Cooperative Extension Bulletin No. 1108, Plasticulture for Commercial Vegetable Production, for a specific schedule of fertilizer injection recommendations for tomatoes.

Planting into Plastic Mulch

Tomatoes are 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 seat(s) mounted behind the water wheel(s) places a transplant into the newly formed hole and covers the rootball. An alternate approach used by many producers is use of a water wheel or similar device to punch holes, with a crew of people walking the field and hand setting plants. The plants are then watered with a water wagon following the setting crews.

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

Other types of transplant methods are available as well. Carousel type planters are sometimes used, which will punch a hole in the plastic and set the plant all in one operation. This equipment requires fewer people to operate since only one person is needed per row. These implements are often slower and usually someone has to walk behind the planter to make sure plants are covered well.

Irrigation

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

Irrigation studies in the southeast show that irrigation increases annual tomato yields by an average of at least 60 percent over dryland production. Quality of irrigated tomatoes is also much better. Irrigation eliminates disastrous crop losses resulting from severe drought.

Tomatoes are potentially deep rooted, with significant root densities up to 4 feet deep. In Georgia soils, however, the effective rooting depth is generally much less. Actual root depths vary considerably depending upon soil conditions and cultural practices. The effective rooting depth is usually 12 to 18 inches with half of the roots in the top 6 inches. It is important not to allow these roots to dry out or root damage will occur.

Moisture stress in tomatoes 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 tomatoes in the southeast. Ultimately, the type chosen will depend on one or more of the following factors:

Sprinkler Irrigation

These 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. There are, however, significant differences in initial cost, fuel cost and labor requirements.

Any sprinkler system used on tomatoes 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 utilization by making it readily available to the plant and reduces leaching.

Drip Irrigation

Drip irrigation has become the standard practice for tomato production. 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 tomatoes. The most dramatic yields have been attained by using drip irrigation and plastic mulch, and supplementing nutrients by injecting fertilizers into the drip system (fertigation).

Drip tubing may be installed on the soil surface or buried up to about 1.5 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. 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, however, you can determine the per acre water capacity by multiplying the output rate of the tube (per 1000') by 8.712 (i.e., on a 5' bed spacing a 4.5 gpm/1000' output rate tube will require 39.2 gpm per acre water capacity).

The tubing is available in various wall thicknesses 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; however, take care in removing it from the field and store it 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. Thoroughly flush drip systems 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 tomatoes 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 tomatoes 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 tomatoes 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. This can be done with soil moisture blocks. For best results on tomatoes, 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 will tend to keep the soil from drying out and tomatoes grow poorly in waterlogged soil.

Physiological Problems

Several physiological problems can affect tomatoes. Most of these are due to specific adverse environmental conditions. Growers can do some things to help minimize their impact, but in many cases not much can be done. In addition, many of these conditions are not well understood, so corrective action is not always possible.

Blossom-End Rot

Blossom-end rot is a calcium deficiency that occurs at the blossom end of the fruit. It is characterized by black, necrotic, sunken tissue at the blossom end. Fruit with necrotic tissue is unsalable and the damage cannot be corrected. Although the tissue is calcium deficient, preplant applications of calcium or postplant applications to correct the disorder often have no effect.

Blossom-end rot develops very early in fruit formation when fruit is smaller than a fingernail, which is a critical time for calcium deposition in newly forming tissue. Calcium is relatively immobile in plants. Once it becomes part of the plant tissue in one location, it cannot be easily moved to new developing tissue. Further, calcium moves in the water stream of the plant’s vascular tissue. So during hot ,dry conditions with high transpiration, calcium uptake may be high but may not be moving laterally into forming fruit. This results in deficiency in these developing tissues even though there is sufficient calcium present in the soil and available to the plant. There is evidence indicating that unstaked and unpruned plants are less likely to have this problem, but in Georgia most tomatoes are staked and pruned for ease of harvest and quality of fresh market fruit.

To a certain extent, this problem can be alleviated with even moisture during plant growth. Wide swings from wet to dry conditions as well as overwatering tend to aggravate this problem. Exogenous applications of calcium as foliar sprays have been suggested to alleviate this problem. Any such application would have to occur prior to visible symptoms when fruit are just forming, but there is little evidence this is an effective practice.

Blossom Drop

Although tomatoes are warm season vegetables, they require relatively moderate temperatures to set fruit. Nighttime temperatures above 70 degrees F. will cause blossom drop, which in turn will reduce yields.

This problem is solved by planting at that time of year when night temperatures will be below this threshold during flowering and fruiting. Transplanting dates for south Georgia would be from March 1 to April 30 in the spring and from July 15 to August 15 in the fall. In north Georgia this would be from April 15 to June 15 in the spring and it is not recommended that tomatoes be grown in the fall. In addition to planting date, there are “hot set” tomatoes available. These tomatoes have been bred to set fruit under higher temperatures (see Table 1 for varieties). For fall planted tomatoes, hot set types are recommended.

Fruit Cracking

Tomato fruit are prone to cracking under certain circumstances. There are two different types of cracking — radial and concentric — both of which occur at the stem end. Radial cracking is more common and usually occurs during periods of high temperatures (at or above 90 degrees F.) and prolonged rain or wet soil when fruit will rapidly expand and often crack. This is particularly prevalent after a long period of dry weather. This type of cracking is also more prone to occur if fruit are exposed to intense sunlight. Finally, fruit load may also be a factor, with a light load more prone to cracking.

Maintaining even moisture conditions, avoiding excessive pruning, and having a heavy fruit load will help prevent this problem. Variety selection can also help alleviate this problem. Varieties are available that are resistant to cracking. Generally, cracking susceptible varieties will crack when fruit are still in the green stage, whereas resistant varieties often don’t show cracking until later, when the fruit is turning color.

Concentric cracking is also caused by rapid growth, but generally occurs when there are alternating periods of rapid growth followed by slower growth. This can occur with wet/dry cycles or cycles of high and low temperatures. Generally this type of cracking occurs as fruit near maturation. Even moisture throughout the growing period will help alleviate this problem. Also avoid fertilization spikes that encourage cyclic growth.

Catfacing

Catfacing is characterized by distorted growth at the blossom end of fruit, often with rough calloused ridges. Catfacing generally occurs when fruit are formed during cool or humid weather that favors the corolla adhering to the developing fruit. The adhesion of these flower parts causes the distortion that appears as the fruit matures. Usually catfacing is most evident during the first harvest with fruit that was set during cooler temperatures. Planting later and using varieties resistant to catfacing will help prevent this from occurring.

Zippering may be related to catfacing, only the damage occurs in straight lines from the blossom end to the stem end. The line may have a calloused or corky appearance.

Puffiness

Fruit may appear normal or nearly so but, when cut, the locules appear empty. There is little or no fruit gel or seeds present. This usually occurs when fruit develop under conditions that are too cool or too hot (below 55 degrees F or above 90 degrees F.), which interferes with normal seed set. Tomatoes are self-fertile but require some disturbance of the flower in order for the pollen to be shaken onto the stigma. This can occur from insects or wind, or during the normal handling of plants (staking and pruning). Wet, humid and cloudy weather may interfere with insect pollination and the pollen may not shed as readily. Cool weather will slow the growth of pollen tubes. In addition, excess nitrogen appears to be a factor with this condition.

Little can be done to alleviate this problem other than planting at the proper time of year. Hot set varieties appear to be less susceptible to this problem.

Sunscald

Tomato fruit may develop a papery thin area on the fruit that will appear tan or white in color. This is caused by sunscald, where the area affected is exposed to intense sunlight and heat resulting in a breakdown of the tissue. Sunscald may also appear as hard yellow areas on the fruit that are exposed. Maintaining good foliage cover during fruit development and avoiding excessive pruning will minimize this problem.

Graywall or Blotchy Ripening and Internal Browning

Several different factors may contribute to these conditions. Internal browning may be caused by a virus (tobacco mosaic virus; see the disease section). Silverleaf whitefly has also been associated with uneven ripeness in tomatoes (see section on insects).

Graywall and blotchy ripening may occur together and may be caused by a bacteria. The outer wall will appear gray and be partially collapsed. Internally there are necrotic areas within the walls of the fruit. Factors associated with this condition include high nitrogen, low potassium, low temperatures, excessive soil moisture and soil compaction. Addressing these factors may reduce the incidence of this disorder.

Internal White Tissue

Occasionally, a tomato will exhibit white tissue in the crosswalls when cut. This is rarely seen when fruit are harvested at the mature green stage, but it can be a problem with vine ripe fruit. It is unclear what causes this, but adequate potassium fertilizer appears to reduce the problem.

Rain Check

Rain check is the formation of tiny transverse cracks on the fruit. These cracks may heal, forming a rough texture on the fruit; generally these fruit are unmarketable.

As with many of these disorders, it is unclear what causes this, but it is associated with rain events. Heavy rains following dry periods are times when this is most likely to occur. This phenomenon may be related to other types of cracking and may be alleviated with growing conditions that don’t encourage wet/dry cycles.

Lime and Fertilizer Management

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 tomatoes. Soil tests results indicate soil pH levels and also provide recommendations for any needed amounts of lime required to raise the pH to the desired range.

The optimum pH range for tomato 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. Lime also adds calcium and, with dolomitic lime, magnesium to the soil.

Calcium has limited mobility in soil, so broadcast and thoroughly incorporate lime 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), lime should be applied and thoroughly incorporated 2 to 3 months before seeding or transplanting. However, 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.

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, and particularly lighter Coastal Plains soils, routinely become deficient in magnesium, dolomitic limestone is usually the preferred liming material.

Fertilizer Management and Application

Recommending a specific fertilizer management program universal for all tomato 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 tomatoes with adequate but not excessive fertility. Applications limited to required amounts result in optimum growth and yield without wasting fertilizer or encouraging luxury consumption of nutrients, which can negatively impact quality or cause fertilizer burn.

Recommendations based on soil tests and comple-mented with plant tissue analyses during the season should result in the most efficient lime and fertilizer management program possible. Valid soil sampling procedures must be used to collect the samples submitted for analyses, however. 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 you have 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 preplant 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 roto-tilling. Additional applications are then made through the drip irrigation system. In bareground culture, pre-plant applications are followed by one to three side-dressed applications. The general crop requirements and application timings for the various nutrients are discussed below.

Starter Fertilizer Solutions

Fertilizer materials 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 tomatoes 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.

Phosphorus and Potassium Recommendations

Table 4 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. As previously discussed, approximately ½ pint of a starter solution should be applied to each transplant.

For early growth stimulation in bare ground culture, pop-up fertilizer should be banded 2 to 3 inches to the side of the plants and 2 to 3 inches below the roots. 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 has approximately a 1 to 3 N to P ratio. It should be relatively high in phosphorus and low in potassium.

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 5 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 tomato production.

Nitrogen 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. Excessive N applications can delay maturity, cause rank vine growth at the expense of fruit set, and reduce shipping quality of fruit.

Table 4. Phosphorous and potassium recommendations for tomato production.
Phosphorous and Potassium Recommendations (lbs/ac)
Phosphorous Ratings	Low	Medium	High	Very High
Recommended P	200	150	100	50
Potassium Ratings	Low	Medium	High	Very High
Recommended K	200	150	100	50
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 because of potentially different methodology and definition of fertility ranges among labs.

Table 5. An example fertilizer injection schedule for a Coastal Plains soil that is low in potassium. The schedule is for a 14-week crop. Extended harvests will require additional injection applications.
Nutrient	Total (lbs/A)	Preplant (lbs/A)	Crop Stage in Weeks (lbs/A/day)
Nutrient	Total (lbs/A)	Preplant (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	1.0
Potassium	225	50	1.0	1.5	2.0	2.5	2.0	1.0

For typical Coastal Plains soils, one-third to one-half 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 5. On bare ground, one to three side dressed applications (possibly four to five applications for 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 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 and, if soil test indicates low, apply 1 pound of actual boron per acre and 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. Leaves of many vegetable plants, however, 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 tomato 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 f4 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 proper fertilizer management of soil applied nutrients is used, then additional supplementation by 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, but neither soil-applied nor foliar-applied nutrients are panaceas.

Quite often after frost or hail occurs, tomato growers apply foliar nutrients to give the plants a boost to promote rapid recovery. If a proper fertilizer program is being used before foliage damage, tomato 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 there is little evidence indicating this is an effective practice. If attempted, 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 in Tables 6 and 7 and are for first flower stage and first ripe fruit stage, respectively, with the sample taken from the most recently mature leaf. Fresh sap can be pressed from the petioles of tomato plants and used to determine nitrogen and potassium nutritional status. Sufficiency ranges for these are listed in Table 8.

References

Maynard, Donald M., and George J. Hochmuth. 1997. Knott’s Handbook for Vegetable Growers 4^th Edition. John Wiley & Sons, Inc. New York.

Olson, S.M., D.N. Maynard, G.J. Hochmuth, C.S. Vavrina, W.M. Stall, M.T. Momol, S.E. Webb, T.G. Taylor, S.A. Smith, and E. H. Simmone. 2005. Tomato Production in Florida in Vegetable Handbook for Florida 2005-2006. Edited by S.M. Olson and E.H. Simmone. Univ. of Florida IFAS Extension. Gainesville, Fla. pp. 357-362.

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 tomatoes — 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 (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 underside 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 USDA 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) and mechanical agitators. These can be purchased separately and put on sprayers. Make sure an agitator is on every sprayer. Some growers make a mistake of not operating the agitator when moving from field to field or when stopping for a few minutes. Always 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 to apply herbicides is one that develops large droplets 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 nozzles 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 fan nozzles. Operate drift reduction and turbo drop nozzles at 40 psi. Operate flooding fan and wide angle cone nozzles 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 overlap 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, consists 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). Liquid is passed through a precision distributor with diagonal slots that produce swirl 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 Arrangements

When applying insecticides and fungicides, it is advantageous to completely cover both sides of all leaves with spray. When spraying tomatoes, 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 in Calibration Method for Hydraulic Boom and Band Sprayers and Other Liquid Applicators, University of Georgia Cooperative Extension Circular 683.

Diseases

Plant diseases are one of the most significant limiting factors to tomato 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 tomatoes in Georgia. This disease is caused by the bacterium Xanthomonas axonopodis pv. vesicatoria. Bacterial spot lesions can be observed on leaves, stems and fruit and occurs during 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 (Figure 7).

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 tomato seed planted for transplants, or direct seeded field grown tomatoes, should be tested by a reputable seed testing company. Transplants should be inspected for bacterial spot lesions before being sold or p

Table 3. Amount of water soluble fertilizer to mix 100 gallons of fertilizer solution.
Fertilizer Source	ppm of nitrogen
	50	100	150	200
	weight (oz.)
20-20-20	3.3	6.7	10.0	13.4
15-0-15	4.4	8.9	13.4	17.8

Table 6. Plant tissue analysis ranges for various elements for tomato sampled at the first flower stage with most recently mature leaves.
	N	P	K	Ca	Mg	S		Fe	Mn	Zn	B	Cu	Mo
Status	Percent							Parts per Million
Deficient <	2.8	0.2	2.5	1.0	0.3	0.3	-	40	30	25	20	5	0.2
Adequate	2.8-4.0	0.2-0.4	2.5-4	1.0-2.0	0.3-0.5	0.3-0.8		40-100	30-100	25-40	20-40	5-15	0.2-0.6
High >	4	0.4	4	2	0.5	0.8		100	100	40	40	15	0.6

Table 7. Plant tissue analysis ranges for various elements for tomato sampled at the first ripe fruit stage with most recently mature leaves.
	N	P	K	Ca	Mg	S		Fe	Mn	Zn	B	Cu	Mo
Status	Percent						-	Parts per Million
Deficient <	2.0	0.2	2.0	1.0	0.25	0.3		40	30	20	20	5	0.2
Adequate	2.0-3.5	0.2-0.4	2.0-4	1.0-2.0	0.25-0.5	0.3-0.6		40-100	30-100	20-40	20-40	5-10	0.2-0.6
High >	3.5	0.4	4	2	0.5	0.6		100	100	40	40	10	0.6

Table 8. Sufficiency ranges for petiole sap tests for tomato at various stages of crop development.
Crop Development Stage	Fresh Petiole Sap Concentration
Crop Development Stage	NO₃ - N	K
First Flower Buds	1000-1200	3500-4000
First Open Flowers	600-800	3500-4000
Fruits 1-inch Diameter	400-600	3000-3500
Fruits 2-inch Diameter	400-600	3000-3500
First Harvest	300-400	2500-3000
Second Harvest	200-400	2000-2500

Table 2. Soil temperature and days to germination.
Soil Temperature (ºF)	60	68	77	85	95
Days to Emergence	14	8	6	5	9


Figure 5. Leaf lesions caused by bacterial spot.	-	Figure 6. Chlorotic leaves caused by bacterial spot.	-	Figure 7. Fruit lesions from bacterial spot.

Commercial Tomato Production Handbook

Foreword