Crop Profile for Tomatoes in Arkansas

General Production Information

• State Rank: 18th
• Percentage of U.S. Production: Less than 2%
• Total acres grown: 1,200 acres (estimated )
• Cash Value: $ 12 to 16 million (estimated )
• Production Regions: Tomato production is distributed throughout Arkansas with the greatest concentration of growers in Bradley, Drew, and Ashley Counties.

The tomato, Lycopersicon esculentum, is a tender, warm season crop belonging to the Solanaceae or nightshade family. Tomatoes prefer a well-drained, loam soil with a soil pH of 5.8-7.2.

Crop rotation is commonly practiced to aid in the reduction of several disease, insect and weed problems. Most growers in Arkansas now produce tomatoes using the plasticulture production system. Use of methyl bromide aids in reduction of soil-borne pests that include weeds, insects and several wilt diseases. Transplants are planted in early spring from March 25 to May 1, and for fall production, during July depending on soil temperature and location in the state. The transplants are planted in single rows at densities of approximately 4000 plants per acre on methyl bromide fumigated, raised beds that are covered with black plastic mulch at 18-24 inches apart and 48-72 inches between rows.

Methyl bromide (67%) + chloropicrin (33%) is currently applied prior to planting (minimum of two weeks between application and planting) transplants for management of soil borne diseases, nematodes, insects, and weeds. A single application of approximately 200 lb. of product per acre is injected into the soil during construction of the plastic covered raised beds. Row middles are not treated. Standard production practices include use of methyl bromide fumigation, raised beds, black polyethylene mulch, and drip-irrigation. Rows are usually spaced five feet apart and plants are usually 18-24 inches apart in the row. Most producers grow their own transplants. Tomatoes are staked, pruned, and tied using the Florida string-weave system. Tomatoes are hand-harvested and often field packed

Tomato plants are normally planted in the spring (March 25 to May 5) into plastic covered beds that are normally fumigated before planting (80 – 90% of the tomato acreage in Arkansas is fumigated with methyl bromide). Approximately 95% of the planting is by hand means. The fumigation normally is done at least 14 days prior to planting (30 days prior to planting is nearer the norm).

Preemergent herbicide applications are applied to the middles beds of mulched tomatoes. These applications are made in early spring, primarily with tractor mounted spray equipment. Postemergence herbicide applications are made to the beds of traditionally grown tomatoes and the row middles of plastic covered beds in early summer and occasionally after harvest primarily with tractor mounted sprayers although backpack sprayers are occasionally used. Hand labor is used to tie and prune the plants above the plastic beginning (May to June).

Insecticides and fungicides are applied from early spring up to harvest primarily with airblast sprayers or boom sprayers.

Virtually the entire tomato crop is hand-harvested (June -July). The tomato plants are normally removed after harvest as well as the plastic mulch. This is all done by hand. The beds are renovated in preparation for fumigation before replanting in the spring.

Aphids or plant lice are among the smallest most preyed on of all insects, yet because of their immense vitality and extraordinary fecundity resulting from a short life cycle and an ability to reproduce parthenogenetically, they affect nearly every kind of green plant, including tomatoes.

Aphids, generally about 1/16 to 1/8 inch long, are usually green, although some species are brown, yellow, pink or black. They can usually be distinguished by the pair of oil- or wax-secreting tubes on the upper side of the fifth or sixth abdominal segment and by their two-segmented tarsi. They feed by thrusting sharp, hollow stylets from their beaks in among the plant cells and sucking out the sap. During the feeding process, they may inject toxic saliva into the plant. The result is a blighting of buds, dimpling of fruits, curling of leaves and the appearance of discolored spots on the foliage.

On tomatoes, the most noticeable injury is the devitalizing of the blossom clusters so that the blossoms fall and no tomatoes set. When large numbers of aphids are present, the plants may gradually wilt, turn yellowish or brown and die. Aphids are among the most important agents in the dissemination of plant virus diseases; a brief period of feeding by a single infected aphid may infect and eventually kill a plant.

Aphids typically winter as fertilized eggs on some perennial plant (particularly roses) or on refuse from annual vegetable crops. The spring hatching nymphs, functioning as stem-mothers, become the start for a great colony of aphids over the growing season. Greenish or pinkish, winged or wingless aphids cluster in shaded places on the leaves, stems and blossoms. Winged migrants spread from field to field so that the epidemic may sweep over a district in an alarming manner. Following such an outbreak, the insect may not visit a community in conspicuous numbers again for many years.

Colorado Potato Beetle
(Leptinotarsa decemlineata)

The Colorado potato beetle is notorious for its ability to rapidly develop resistance to insecticides that are used repeatedly for control. This has been a serious problem on the east coast for some time, and is becoming more of a problem in Arkansas. With a limited number of insecticides available, some growers feel they have exhausted their control options when it becomes resistant to one or more insecticides

In tomatoes Colorado potato beetle is an infrequent pest of newly set tomato plants. The adult and larva feed on the leaves and terminal growth of tomato plants, but typically only cause serious damage to young plants. Once plants reach eight inches, adult or larval feeding, regardless of the apparent severity of damage, does not reduce fruit yield.

Colorado potato beetles overwinter in the soil as adults. They become active in the spring as temperatures rise and begin to feed on weeds and volunteer or early planted potatoes, even entering the soil to attack emerging foliage. Female beetles lay orange-yellow eggs in batches of approximately two dozen on the underside of the leaves. Each female can lay 500 or more eggs over a four to five week period. Eggs hatch in four to nine days and the larvae begin to feed on potato foliage. The larvae are humpbacked with two rows of black spots on each side. They usually feed in groups and damage can be severe. The larval stage lasts two to three weeks.

Full grown larvae burrow in the ground to pupate. In five to 10 days, the adult beetle emerges. This insect can go from egg to adult in as little as 21 days. The newly emerged adult female feeds for a few days before egg laying begins. There are two full and occasionally a partial third generation each year. If foliar sprays are used, an effort should be made to treat just after most eggs have hatched but before serious plant damage occurs.

Cutworms
(Various species)

Several species of cutworms can occasionally be serious pests of newly set tomatoes in Arkansas. As in other crops, the seedling losses caused by cutworms result in reduced stands.

Tomato Fruitworm
(Heliothis zea)

The tomato fruitworm is potentially the most damaging insect pest of tomato. The larvae are variable in color, ranging from pale yellow, to red, to green, to brown with pale stripes running lengthwise. The larvae have four pairs of prolegs and are densely covered with microscopic spines that makes the larvae feel rough.

The moths lay eggs at night on leaves near green fruit at the outer edges of the plant. The dome shaped eggs are white when first laid and develop a reddish brown band before hatching. After the egg hatches, the larva feed for a short period of time on the foliage before attacking the fruit. They prefer to feed on green fruit and usually do not enter ripe fruit. Damage consists of deep watery cavities frequently in the stem end of the fruit. During its development, one larva may injure several fruit.

The tomato fruitworm has a wide host range and the attractiveness of tomatoes for egg laying vary with the time of year. Early fruitworm generations attack corn, particularly when it is silking. Tomatoes are preferred for egg laying over corn when the silks turn brown and dry.

Flea Beetles
(Epitrix cucumeris and Epitrix hirtipennis)

Flea beetles attack the foliage leaving small round holes in the leaves and large numbers may destroy entire leaves. Potentially they can be serious pests early in the season when the plants are less than 4 to 6 inches tall. As they grow, larger plants can withstand substantial flea beetle damage without loss of yield

As soon as the plants are set, they are vulnerable to attack by two species of flea beetles, the tobacco and potato flea beetles. The tobacco flea beetle is about the same size, but is yellowish brown with a dark band across its wings. The potato flea beetle is about 1/10 inch and brownish black in color. These beetles infest solanaceous crops such as tobacco, potato, tomato, and pepper.

Two Spotted Spider Mite
(Tetranychus urticae)

Two-spotted spider mites are occasional pests that can cause serious damage to some vegetable crops during hot dry weather. Mites can injure tomatoes, beans, muskmelons, watermelons, and sweet corn. Extended periods of hot, dry weather favors mite buildups. Infestations usually first occur at the edge of a field, typically near rank weed growth or dirt roads. Mites can also be easily moved from infested plants to non-infested plants on clothing.

Generally mites feed on the undersides of leaves. They use their sucking mouthparts to remove sap from plants, giving the upper leaf surface a speckled or mottled appearance. Leaves of mite infested plants may turn yellow and dry up, and plants may lose vigor and die when infestations are severe. The underside of affected leaves appear tan or yellow and have a crusty texture. Heavy infestations of the two-spotted spider mite produce fine webbing which may cover the entire plant.

Stink Bugs
(Acrosternum hilare, Euschistus servus)

Green stink bug (Acrosternum hilare) and brown stink bug (Euschistus servus) attack vegetable crops including tomatoes. Stink bugs have a distinctive shield shape and produce an odor when handled. There are several species of stink bugs that feed on tomato fruit, but the brown stink bug is the most serious. Stink bugs feed with piercing sucking mouthparts which cause whitish-yellow corky spots underneath the skin of the fruit. This damage is serious for fresh market tomatoes and whole-pack processing tomatoes because they render the fruit unmarketable

Adult stink bugs migrate from weedy areas into tomato fields, particularly when the plants begin to decline. On green fruit, stink bug damage appears as a pin prick, surrounded by a light discolored area. This may turn yellow or remain green on ripe fruit and the tissue below these spots corky.

Whiteflies
(Bemisia tabaci and Trialeurodes vaporariorum)

The sweet potato whitefly has flat, oval, greenish nymphs which suck sap from plants, excreting copious amounts of sticky honeydew and are the vectors of a complex of virus diseases including lettuce infectious yellows and squash silver leaf. More than 420 plant species are hosts. The whitefly is a very destructive pest of vegetable crops. The adults are typical four-winged whiteflies about 1/16 inch long. In greenhouses, breeding is continuous. The greenhouse whitefly leaves plants covered, especially on the undersides, with small, snow-white, four-winged flies and very small, oval, flat, pale-green nymphs, less that 1/30 inch in length, which suck the sap. Infested plants are lacking in vigor, wilt, turn yellow and die. The leaves are covered with a coating of glazed, sticky material on which a sooty-colored fungus often grows, completely covering the foliage. Tomatoes are significantly impacted by this pest. They suck the sap from the leaves, feeding greedily on the plant juices for about 4 weeks. In the course of this time, they pass through four instars. The average duration of the nymphal periods is about 28 to 30 days. The adult whitefly is about 1/16 inch in length, very active, four-winged, with a yellowish body and has the appearance of having been thoroughly dusted with some very fine white material. Both males and females fly, and they feed, like the nymphs, on the undersides of the leaves, living from 30 to 40 days. Under greenhouse conditions, the generations overlap, and all the stages of the insect may be found on infested plants at any time.

Weeds that infest tomatoes in Arkansas include annual grasses: Broadleaf signalgrass (Brachiaria platyphylla), Crabgrass (Digitaria spp.), Goosegrass (Eleusine indica), and Fall panicum (Panicum dichotomiflorum); perennial grasses: Johnsongrass (Sorghum halepense); and broadleaf weeds; Common cocklebur (Xanthium strumarium), Groundcherry (Physalis angulata), Jimsonweed (Datura stramonium ), Common lambsquarters (Chenopodium album), Morningglory (Ipomea spp.), Nutsedge (Cyperus spp.), Smooth pigweed (Amaranthus hybridus), Common ragweed (Ambrosia artemisiifolia), Pennsylvania smartweed (Polygonum pensylanicum), Sicklepod (Cassia obtusifolia), and Velvetleaf (Abutilon theophrasti). Weeds, if uncontrolled, can cause as much as 50 to 70 percent reduction in tomato yield. Tomatoes must be nearly weed-free from transplanting to flowering for optimum yield and quality.

In bareground (no plastic) tomatoes, weeds must be managed with preplant or preemergence herbicides. Preplant herbicides are applied before transplanting. Certain preplant herbicides (paraquat) kill emerged weeds and do not suppress weed germination, while others (metribuzin, pebulate, or napropamide) are incorporated to suppress weed emergence. Preemergence herbicides (metribuzin, napropamide) are applied after tomato transplanting and before weed emergence. Postemergence weed control is achieved by using either postemergence herbicides (metribuzin, paraquat, sethoxydim) or hand removal and early cultivation.

In tomatoes grown using black plastic, preemergence and postemergence herbicides are used to control weeds in middles between the plastic rows. Cultivation (between plastic rows) is not used because the cultivators may damage the plastic and increase erosion.

Mechanical control:
Tomatoes grown on bare ground are cultivated twice during the season. Weeds that emerge near the tomato plants are generally hand-removed although the widespread use of methyl bromide fumigation has greatly reduced the amount of hand weeding.

• Methyl bromide
  This material (240 lb a.i./acre) is injected into the soil under plastic for disease control. An additional benefit is that it prevents weeds from emerging through the same hole that the tomato plant uses to grow through the plastic. It is used on approximately 25 percent of the tomato acreage. See specific label for PHI and REI.
• Paraquat
  This non-selective herbicide (Gramoxone Extra 2.5L at 0.6-0.9 lb a.i./acre) is applied to control emerged annual weeds before tomato transplanting. It is used on approximately 25 percent of the acreage. PHI: N/A. REI: 12 hours
• Metribuzin
  Applied preplant incorporated, this material (Lexone or Sencor 75DF at 0.25-0.5 lb a.i./acre) targets annual grasses and broadleaf weeds. It gives excellent control of common lambsquarters, common ragweed, hairy galinsoga, jimsonweed, most pigweeds, purslane, sicklepod, and certain annual grasses. It is used on approximately 20 percent of the tomato acreage. PHI: 7 days. REI: 12 hours.
• Napropamide
  Applied preplant incorporated, this material (Devrinol 50DF at 1-2 lbs a.i./acre) is used to control annual grasses and broadleaf weeds, including common purslane, pigweeds, and hairy galinsoga. It is applied to approximately 7 percent of the tomato acreage. PHI: N/A. REI: 12 hours.

Preemergence herbicides

• Metribuzin
  This material (Lexone or Sencor 75DF at 0.33-0.67 lb a.i./acre) is applied preemergence for controlling annual grasses and broadleaf weeds. It gives excellent control of common lambsquarters, common ragweed, hairy galinsoga, jimsonweed, most pigweeds, purslane, sicklepod, and certain annual grasses. It is used on approximately 45 percent of the tomato acreage. PHI: 7 days. REI: 12 hours
• Napropamide
  Applied preemergence, this material (Devrinol 50DF at 1-2 lbs a.i./acre) controls annual grasses and broadleaf weeds, including common purslane, pigweeds, and hairy galinsoga. It is applied to approximately 5 percent of the tomato acreage. PHI: N/A. REI: 12 hours.

Postemergence herbicides

• Paraquat
  This material (Gramoxone Extra 2.5L at 0.5 lb a.i./acre) is applied as a shielded, postdirected application to emerged weeds. It is most effective on small, actively growing broadleaf weeds. It is applied to approximately 70 percent of the acreage an average of three times per season. PHI: N/A. REI: 12 hours
• Metribuzin
  This postemergence material (Lexone or Sencor 75DF at 0.33-1.33 lbs a.i./acre) is used to control small weeds. It is most effective for controlling broadleaf weeds. It is applied to approximately 60 percent of the tomato acreage. Lexone or Sencor are sometimes applied with sethoxydim (Poast) to broaden their control. PHI: 7 days. REI: 12 hours.
• Sethoxydim
  Applied postemergence, this material (Poast 1.53EC at 0.2-0.3 lb a.i./acre) controls annual and perennial grasses. It is used on approximately 40 percent of the tomato acreage. PHI: 20 days. REI: 12 hours

Diseases

Anthracnose
(Colletotrichum spp.)

Control of anthracnose is especially important for processing tomatoes because quality standards include mold counts. In fresh market operations it will be a serious concern only if fully ripe fruit are involved, such as with roadside markets. The recommendations for anthracnose are written for processing crops. With fresh market tomatoes the program used for early blight should be sufficient to control anthracnose. Anthracnose occurs mainly as sunken circular spots on ripe fruits with the sporulating fungus appearing as a dark mass in the center of the lesion. It is particularly troublesome on fruit that is overripe and in contact with the soil. Although infections can occur early (when fruits are green and small), this is primarily a disease of ripe fruit.

Bacterial Canker
(Clavibacter michiganensis michiganenese)

Bacterial Canker is an increasingly important disease in Arkansas which can cause serious losses during cool summers and in fall crops. It occurs in many forms as a fruit spot, leaf blight, stem canker or vascular wilt, depending on whether the pathogen is localized or systemic. Under Arkansas weather conditions, the bacterium becomes established on the foliage of healthy plants and invades the plant through wounds and natural openings. Prevention is the only recommended strategy for control.

The canker pathogen is seed and transplant-borne; it overwinters on tomato debris (on roots and large stems) plus stakes and other field and greenhouse items. Once present, the bacterium is easily spread during wet conditions by splashing rain, irrigation water, machinery and workers.

Bacterial Speck and Bacterial Spot
(Pseudomonas syringae pv. tomato and Xanthomonas campestris pv. vesicatoria)

Bacterial Spot mainly occurs on the foliage as dark, angular spotting with yellow halos and scabby lesions of the fruit. Bacterial Speck causes similar spots on the foliage but black specks on the fruit. Spot is favored by warm wet weather while bacterial speck is more likely in cool, wet conditions. The incidence and severity of spot and speck have markedly increased recently, probably due to the production of hybrid seed in tropical climates.

Blossom End Rot

Blossom End Rot is not an infectious disease, rather a physiological disorder related to calcium movement or calcium deficiency promoted by variances in water availability and growth flushes. Blossom End Rot is aggravated by improper fertility programs (e.g. high levels of ammonium nitrogen or high levels of potassium).

Cultural: Growers usually take soil tests to insure adequate calcium levels in the soil. Applications of calcium nitrate can help minimize the problem. Mulching of tomatoes reduces blossom end rot (most growers use plasticulture). Uniform soil moisture is important in controlling the disorder. Growers try to avoid sudden injury to healthy roots by close cultivation as well as sites subject to standing water or flooding because theycan increase the incidence of blossom end rot.

Application Alternatives used in Arkansas:

Calcium sprays are not considered effective in reducing Blossom End Rot in field plantings.

Buckeye Fruit Rot
(Phytophthora parasitica)
Pythium Stem Rot and Fruit Rot
(Pythium spp.)

Buckeye Rot occurs as circular, zonate lesions on the fruits while Pythium causes a water rot of the fruit. In stake tomatoes, these are problems mainly on the lower fruits which receive soil splash. Both cause dark watery rots of the stem near the soil line, mainly of young plants.

Early Blight
(Alternaria solani)

Early Blight (the most common foliage disease of tomatoes in Arkansas) mainly affects older foliage causing dark brown, target-like spots and general blighting of the foliage, stem cankers and fruit rot.

Gray Leaf Mold is more common in the greenhouse than field but can be severe under low light situations in the field, occurring as a yellow spot on foliage with gray fungus growth on the bottom side of the leaf.

Gray Leaf Spot is often found on transplants upon arrival from southern areas and/or from hot, humid greenhouses. Spots are irregular in shape, brown with extensive yellowing. In the field, it has been mainly a problem with late crops.

Septoria Leaf Spot/Blight occurs frequently and dominates in some seasons, as small gray/tan spots with dark borders, usually with dark fruiting bodies of the fungus evident in the center of each spot.

Late Blight
(Phytophthora infestans)

Late blight can very quickly destroy a commercial tomato crop under cool, wet weather. This disease causes dark, irregular spots (often worse on the youngest foliage) giving a scalded appearance to the foliage. Fruit appear as if rolled on a hot plate. Late blight appears erratically in Arkansas; it is more common in the mountains and during fall plantings. The disease has been observed more frequently nation-wide in recent years with new strains and increased disease levels. Significant epidemics are much more likely in the future, so it is important to keep controls in place when the threat of late blight exists.

The control program listed for early blight is adequate for most cases of late blight in Arkansas. Close spray intervals, obtaining good coverage, and keeping the fixed coppers together with the chlorothalonil or mancozeb/maneb are all recommended and utilized by growers. Under very strong late blight pressure, chlorothalonil usually provides superior control. Quadris at 6.2 fl oz/A is a new option, but no more than two sequential applications can be made before switching back to the other fungicides to help manage resistance. All outbreaks in Arkansas investigated since 1992 have involved the mefenoxam/metalaxylresistant (tolerant) strains of the fungus. Therefore, these fungicides are no longer recommended for this disease.

Sclerotinia Stem Rot
(Sclerotinia sp.)

These diseases occur as girdling cankers on the main stems, usually resulting from transplanting infected plants or occasionally from high populations of the pathogens that can naturally occur in the soil. Botrytis gray mold occurs mainly as a rot of the leaf and fruit under prolonged cool, wet conditions and is becoming more common in fall plantings of tomatoes in Arkansas. It also occurs in the spring along with Sclerotinia as stem lesions on young plants. Adding Benlate to the spray program will aid in control if the strain is sensitive to benomyl.

Powdery Mildew
(Oidium lycopersicum)

Several serious cases of powdery mildew of tomatoes were diagnosed in 1998/99. This disease causes a white mildew and can lead to defoliation of the plants. Most cases have been in the greenhouse although some have been in the field. In all field outbreaks, the spray program being used for other foliar diseases was inadequate.

Southern Stem Blight or Southern Blight
(Sclerotium rolfsii)

Plants wilt and die from girdling of the roots and stem at the soil line. The white fungus and its fruiting bodies (resembling mustard seeds) are normally present at the soil line. Traditionally, this has been a southern disease, but it has been on the increase during the past decade. Avoid fields with a history of this disease on any crop. This disease is often introduced on field grown transplants from the south. The pathogen has a wide host range and can colonize almost any plant material as the tissue dies. The pathogen moves onto tomato plants from colonized debris.

Pesticides used for southern stem blight contol in Arkansas:

PCNB (Terrachlor 75 WP) - Applied at 10 lb/100 gallon using 0.5 pt/plant sprayed in the planting trench and on soil at transplanting may be warranted for serious cases. This is not a transplant water treatment although some areas report good success when using it in the setter water. PHI: N/A. REI: 12 hours.

Viruses

Virus diseases cause a range of conditions including mosaic and mottling, stunting, poor fruit quality and even plant death. Tomato spotted wilt (TSWV) is a relatively new problem which is arriving mainly on infected transplants.

Due to heavy soils, nematodes have not caused the level of crop damage often present in the south. Root knot nematode is the most common in Arkansas; it deforms the root system resulting in stunting, early firing of foliage, and low yields.

Profile Compiled by:

Contact Personnel:

1. Andersen, Dr. Craig R., Extension Horticulturist – Vegetables. MP-128, Vegetable Gardening in Arkansas. University of Arkansas, Division of Agriculture, Cooperative Extension Service, 1997.

2. MP 144, 2003 Insecticide Recommendations for Arkansas. University of Arkansas, Division of Agriculture, Cooperative Extension Service, 2003.

3. MP-44, 2003 Recommended Chemicals for Weed and Brush Control. University of Arkansas, Division of Agriculture, Cooperative Extension Service, 2003

4. MP-154 Plant Disease Control Handbook. University of Arkansas, Division of Agriculture, Cooperative Extension Service, 1991.

5. Statistics of Vegetables and Melons, USDA, National Agricultural Statistics Service, Crops Branch, 1999.

6. USDA, National Statistics Service, Census of Agriculture-Arkansas, 1997.

7. Crop Profile for Tomatoes in Tennessee. July 2002. USDA Pest Management Center

8. Crop Profile for Tomatoes in Kentucky. September 2001. USDA Pest Management Center