Tomato Diseases & Disorders

Tomatoes (Solanum lycopersicum) can be grown on almost any moderately well-drained soil type. A good supply of organic matter can increase yield and reduce production problems. Tomatoes and related vegetables, such as potatoes, peppers, and eggplants, should not be planted on the same land more than once in three years. Ideally, any cover crop or crop preceding tomatoes should be members of the grass family. Corn, an excellent rotation crop with tomatoes, supplies large amounts of organic matter and does not promote the growth of disease organisms that attack tomatoes. Certified seeds and plants are recommended and should be used whenever possible.

Bacterial Wilt

Bacterial wilt or Southern bacterial blight is a serious disease caused by Ralstonia solanacearum (formerly Pseudomonas solanacearum). This bacterium survives in the soil for extended periods and enters the roots through wounds made by transplanting, cultivation, insect feeding damage, and natural wounds where secondary roots emerge.

Disease development is favored by high temperatures and high moisture. The bacteria multiply rapidly inside the water-conducting tissue of the plant, filling it with slime. This results in rapid wilt of the plant while the leaves stay green. If an infected stem is cut crosswise, it will look brown and tiny drops of yellowish ooze may be visible.

Prevention & Treatment: Control of bacterial wilt of plants grown in infested soil is difficult. Rotation with non-susceptible plants, such as corn, beans, and cabbage, for at least three years provides some control. Do not use pepper, eggplant, potato, sunflower, or cosmos in this rotation. Remove and destroy all infected plant material. Plant only certified disease-free plants. The cultivar Kewalo is partially resistant to bacterial wilt but is an uncommon cultivar. Chemical control is not available for this disease.

Consider growing all susceptible solanaceous plants (tomatoes, peppers, eggplants, and Irish potatoes) in a separate newly prepared garden site, completely separate from the original garden. Be sure to thoroughly hose off all soil from tiller tines and tools used in the original infested site before use in the new garden site.

Recently, several bacterial wilt resistant rootstocks for grafted tomatoes, peppers, and eggplants have been tested and found to have a high level of resistance. Grafted plants may be available.

Early Blight

This disease is caused by the fungi Alternaria linariae (formally known as A. solani) and is first observed on the plants as small, brown lesions mostly on the older foliage. Spots enlarge and concentric rings in a bull’s-eye pattern may be seen in the center of the diseased area. The tissue surrounding the spots may turn yellow. If high temperature and humidity occur at this time, much of the foliage is killed. Lesions on the stems are similar to those on leaves and sometimes girdle the plant if they occur near the soil line (collar rot). On the fruits, lesions attain considerable size, usually involving nearly the entire fruit. Concentric rings are also present on the fruit. Infected fruit frequently drops.

The fungus survives on infected debris in the soil, on seed, on volunteer tomato plants, and other solanaceous hosts, such as Irish potato, eggplant, and black nightshade (a common, related weed).

Prevention & Treatment: Use resistant or tolerant tomato cultivars. Use pathogen-free seed and do not set diseased plants in the field. Use crop rotation, eradicate weeds and volunteer tomato plants, space plants to not touch, mulch plants, fertilize properly, don’t wet tomato foliage with irrigation water, and keep the plants growing vigorously. Trim off and dispose of infected lower branches and leaves.

To reduce disease severity, test the garden soil annually and maintain a sufficient level of potassium. Lime the soil according to soil test results. Side dress tomato plants monthly with calcium nitrate for adequate growth.

If the disease is severe enough to warrant chemical control, select one of the following fungicides: mancozeb (very good); chlorothalonil or copper fungicides (good). Follow the directions on the label. See Table 1 for examples of fungicide products for home garden use. See Table 2 for tomato cultivars with resistance or tolerance to early blight.

Late Blight

Late blight is a potentially serious disease of potato and tomato and is caused by the water mold pathogen Phytophthora infestans. Late blight is especially damaging during cool, wet weather. This pathogen can affect all plant parts. Young leaf lesions are small and appear as dark, water-soaked spots. These leaf spots will quickly enlarge, and a white mold will appear at the margins of the affected area on the lower surface of leaves. Complete defoliation (browning and shriveling of leaves and stems) can occur within 14 days from the first symptoms. Infected tomato fruits develop shiny, dark, or olive-colored lesions, which may cover large areas. Fungal spores are spread between plants and gardens by rain and wind. A combination of daytime temperatures in the upper 70s °F with high humidity is ideal for infection.

Prevention & Treatment: The following guidelines should be followed to minimize late blight problems:

• Keep foliage dry. Locate your garden where it will receive morning sun.
• Allow extra room between the plants, and avoid overhead watering, especially late in the day.
• Purchase certified disease-free seeds and plants.
• Destroy volunteer tomato and potato plants, as well as nightshade family weeds, such as Carolina horsenettle or black nightshade, which may harbor the fungus.
• Do not compost rotten, store-bought potatoes.
• Pull out and destroy diseased plants.
• If the disease is severe enough to warrant chemical control, select one of the following fungicides: chlorothalonil (very good), copper fungicide, or mancozeb (good). See Table 1 for examples of fungicide products for home garden use. Follow the directions on the label.
• Plant resistant cultivars. See Table 3 for tomato cultivars with resistance to late blight.

Septoria Leaf Spot

This destructive disease of tomato foliage, petioles, and stems (fruit is not infected) is caused by the fungus Septoria lycopersici. Infection usually occurs on the lower leaves near the ground, after plants begin to set fruit. Numerous small, circular spots with dark borders surrounding a beige-colored center appear on the older leaves. Tiny black specks, which are spore-producing bodies, can be seen in the center of the spots. Severely spotted leaves turn yellow, die, and fall off the plant. The fungus is most active when temperatures range from 68 to 77° F, the humidity is high, and rainfall or overhead irrigation wets the plants. Defoliation weakens the plant, reduces the size and quality of the fruit, and exposes the fruit to sunscald (see below). The fungus is not soil-borne but can overwinter on crop residue from previous crops, decaying vegetation, and on some weeds related to tomato.

Prevention & Treatment: Most currently grown tomato cultivars are susceptible to Septoria leaf spot. Crop rotation of 3 years and sanitation (removal of crop debris) will reduce the amount of inoculum. Do not use overhead irrigation. Repeated fungicide applications with chlorothalonil (very good) or copper fungicide, or mancozeb (good) will keep the disease in check. See Table 1 for examples of fungicide products for home garden use.

Leaf Mold

The fungus Passalora fulva causes leaf mold. It is first observed on older leaves near the soil where air movement is poor and humidity is high. The initial symptoms are pale green or yellowish spots on the upper leaf surface, which enlarge and turn a distinctive yellow.

Under humid conditions, the spots on the lower leaf surfaces become covered with a gray, velvety growth of the spores produced by the fungus. When infection is severe, the spots coalesce, and the foliage is killed. Occasionally, the fungus attacks stems, blossoms and fruits. Green and mature fruit can have a black, leathery rot on the stem end.

The fungus survives on crop residue and in the soil. Spores are spread by rain, wind, or tools. Seeds can be contaminated. The fungus is dependent on high relative humidity and high temperature for disease development.

Prevention & Treatment: Crop residue should be removed from the field. Staking and pruning to increase air circulation helps to control the disease. Space tomato plants further apart for better air circulation between plants. Avoid wetting leaves when watering. Rotate with vegetables other than tomatoes. Using a preventative fungicide program with chlorothalonil, mancozeb, or copper fungicide, can control the disease. See Table 1 for fungicide products for home garden use.

Bacterial Spot

This disease is caused by several species of the bacterium Xanthomonas (but primarily by Xanthomonas perforans), which infect green but not red tomatoes. Peppers are also infected. The disease is more prevalent during wet seasons. Damage to the plants includes leaf and fruit spots, which result in reduced yields, defoliation, and sunscalded fruit. The symptoms consist of numerous small, angular to irregular, water-soaked spots on the leaves and slightly raised to scabby spots on the fruits. The leaf spots may have a yellow halo. The centers dry out and frequently tear.

The bacteria survive the winter on volunteer tomato plants and on infected plant debris. Moist weather is conducive to disease development. Most outbreaks of the disease can be traced back to heavy rainstorms that occurred in the area. Infection of leaves occurs through natural openings. Infection of fruits must occur through insect punctures or other mechanical injuries.

Bacterial spot is difficult to control once it appears in the field. Any water movement from one leaf or plant to another, such as splashing raindrops, overhead irrigation, and touching or handling wet plants, may spread the bacteria from diseased to healthy plants.

Prevention & Treatment: Only use certified disease-free seeds and plants. Avoid areas that were planted with peppers or tomatoes during the previous year. Avoid overhead watering by using drip or furrow irrigation. Remove and dispose of all diseased plant material. Prune plants to promote air circulation. Spraying with a copper fungicide will give fairly good control of the bacterial disease. Follow the instructions on the label. See Table 1 for fungicide products for home garden use.

Tomato Pith Necrosis

Tomato pith necrosis is usually an early season disease that occurs in greenhouse and high tunnel tomato production. However, during cool and rainy spring weather, tomato pith necrosis may infect tomatoes and occasionally peppers in home vegetable gardens. Pith necrosis is caused by multiple species of soil-borne Pseudomonas bacteria, including Pseudomonas corrugata, as well as Pectobacterium carotovorum

(a cause of bacterial soft rot). These bacteria are considered weak pathogens that infect rapidly growing tomato plants during cloudy, cool, and moist environmental conditions.

Symptoms: The early symptoms of this disease are blackened (necrotic) areas on the stems, which may first appear adjacent to leaf petioles. The blackened areas coalesce and extend as a band along the stem, as well as out onto the leaf petioles. Portions of leaf blades also may become blackened following infection of the leaf petiole.

As the disease progresses, the bacteria colonize the interior of the stems, which may cause the stem to split. Stems may shrink, crack, and the pith (the stem interior) may become segmented or laddered. Eventually, the stems become hollow inside. This stem damage cuts the water supply off to the upper portions of the tomato plant so that upper leaves may yellow and the shoots wilt.

Another symptom is the production of large numbers of adventitious roots that burst forth from larger stems. However, this type of root formation on stems also occurs with tomato bacterial canker and from damage by spray drift exposure by dicamba, which is a very common broadleaf weed killer for use on lawns.

Symptoms on green developing fruit may or may not be present, which is a greasy, water-soaked area on the blossom end of the fruit. This fruit symptom is very similar to that of two other diseases called late blight and buckeye rot of tomato.

Identify which disease is affecting the tomato crop by submitting a plant sample through the local Extension office. The plant material will be sent for a fee to the Clemson Plant & Pest Diagnostic Clinic for diagnosis and control recommendations.

Control: As the weather becomes warmer, plants may recover as the rapid spring growth slows. Do not use over-head irrigation to water the garden, but water at the base of the plants by drip irrigation, soaker hoses, or by hand with a garden hose. The frequency of irrigation should be increased to provide adequate soil moisture for recovery. However, if plants succumb to pith necrosis, carefully remove and dispose of diseased plants, including roots.

This disease severity is enhanced by excessive nitrogen fertilization during early season growth. Follow fertilization recommendations by soil test results. For more information, see HGIC 1652, Soil Testing, and HGIC 1323, Tomato.

Because these soil-inhabiting bacteria can exist in the soil until the next season, practice a 3-year crop rotation within the vegetable garden. In the future, space out tomato plants in the garden to 3 feet apart. This will improve air circulation around plants and enhance the drying of foliage from dew or rainfall. Plant according to the recommended spring planting dates in HGIC 1256, Planning a Garden. Avoid planting in early spring when conditions are cool and moist. There are no spray treatments to reduce disease.

Buckeye Rot

Buckeye rot is a disease of the fruit caused by the fungus Phytophthora nicotianae var. parasitica. The first fruit symptoms appear as brownish spots, often at the point of contact between the fruit and the soil. As the spots enlarge, dark, concentric rings can be seen. Lesions of buckeye rot resemble those of late blight, except that the former remain firm and smooth, whereas late blight lesions become rough and are slightly sunken at the margins. Under moist conditions, a white, cottony fungal growth appears on the buckeye rot lesions. With time, the entire fruit will rot. The fungus does not affect the foliage. The disease is most common during periods of prolonged warm, wet weather and in poorly drained soils. The fungus survives in the soil and is spread by surface water and rain. Peppers are also susceptible to this disease.

Prevention & Treatment: Avoid compacted, poorly drained soils (grow plants in raised beds). Rotation, sanitation, staking, and mulching will help reduce the disease. Fungicide sprays with chlorothalonil, mancozeb, or copper fungicides will give fairly good control of buckeye rot. See Table 1 for examples of fungicide products for home garden use.

Anthracnose

Anthracnose on tomatoes is caused by a group of fungi within the genus Colletotrichum, and these species are primarily pathogens of the tomato fruit. As the fruit are ripening, the symptoms first become noticeable as small, circular indented areas, which later develop darkened centers. The diseased spots continue to grow larger with time as each infection site also spreads deeper into the fruit. With warm, moist, and humid weather (from rainfall or overhead irrigation), the fungus produces salmon-colored spores that are exuded from the black fungal material in the center of the spots. These spores are spread by splashing water.

Prevention & Treatment: Purchase disease-free seed, as the fungus that causes anthracnose of tomato may be within the seed. Tomato seed may be treated by soaking them in hot water (122 ºF) for 25 minutes to destroy the fungus. Some varieties of tomatoes have resistance to anthracnose, such as Chef’s Choice Orange Hybrid.

Do not overhead irrigate tomatoes, as splashing water aids in the spread of fungal spores. Plant the garden in a sunny site and stake or cage tomato plants to provide better air movement and leaf drying conditions. Keep the garden weed-free, as the presence of weeds may raise humidity levels around plants and slow drying conditions.

Because this disease affects other plants in the tomato family (Solanaceae), such as eggplants and peppers, the site for the tomatoes should not be planted again with solanaceous plants for at least a year. Some weeds that infest the garden are also in the same family, which is another reason to keep the garden free of weeds. Fungal spores can remain in the soil to infect plants the following year. Mulching the garden helps create a barrier between the soil surface and the fruit to reduce infections.

Some insects feed on ripe fruit, such as leaf-footed plant bugs and stink bugs. Their feeding punctures the skin of the fruit and allows the fungus to infect.

Harvest tomato fruit daily as soon as they are ripe. Remove and destroy crop debris as soon as the crop has finished bearing. Do not add debris to compost.

Fungicide sprays can help reduce disease. Products containing mancozeb or chlorothalonil can be sprayed weekly to reduce infection. Follow label directions. There is a five-day waiting period between spraying and picking if using mancozeb, and a one-day waiting period for using chlorothalonil. See Table 1 for examples of products containing this active ingredient.

Fusarium Wilt

This is a warm-weather disease caused by the fungus Fusarium oxysporum. The first indication of disease in small plants is a drooping and wilting of lower leaves with a loss of green color followed by wilting and death of the plant. Often leaves on only one side of the stem turn golden yellow at first. The stem of wilted plants shows no soft decay, but when cut lengthwise, the lower stem will have a dark brown discoloration of the water-conducting vessels. The fungus is soil-borne and passes upward from the roots into the water-conducting system of the stem. Blocking of the water-conducting vessels is the main reason for wilting. Invasion occurs through wounds in roots growing through infested soil. Long-distance spread is through seed and transplants.

Prevention & Treatment: For control, grow plants in pathogen-free soil, use disease-free transplants, and grow only cultivars with at least resistance to races 1 and 2 of Fusarium wilt (indicated by FF following the tomato cultivar name). Some newer cultivars are resistant to races 1, 2, and 3, and are found listed in Table 4. Raising the soil pH to 6.5 – 7.0 and using nitrate nitrogen (such as in calcium nitrate) rather than ammoniacal nitrogen (as in 5-10-10, 10-10-10, or 34-0-0) will retard disease development. No chemical control is available.

Southern Blight

The fungus Athelia rolfsii (previously called Sclerotium rolfsii) causes this disease. The first symptom is the drooping of leaves suggestive of other wilts. On the stems, a brown, dry rot develops near the soil line. White fungal growth with brown mustard seed-sized sclerotia may be visible. The stem lesion develops rapidly, girdling the stem and resulting in sudden and permanent wilt of all aboveground parts. Frequently, a white fungal mat covers the lesions. The fungus can also attack fruits where they touch the soil.

The fungus can survive for years in soil and plant debris. It is favored by moist conditions and high temperatures.

Prevention & Treatment: Crop rotation with non-susceptible grass crops and removal of plant debris immediately after harvest will help to control the disease. Do not plant tomatoes after beans, pepper, or eggplant. Calcium nitrate may be applied at transplanting.

Seedling Disease (Damping-off)

The fungi Pythium and Rhizoctonia cause damping-off of tomato seedlings. Seedlings fail to emerge from the soil in the greenhouse, or small seedlings wilt and die soon after emergence or transplanting. Surviving plants have water-soaked areas on the stem close to the soil line.

Prevention & Treatment: Damping-off is often a problem in plants that are planted too early in the spring. The fungi are more active in cool, wet, rich soils. To prevent damping-off, take these precautions:

• Start seeds indoors in sterilized potting mix and use new or clean containers.
• Do not start seeds in soil that has a high nitrogen level. Add nitrogen fertilizer after the seedlings have produced their first true leaves.
• Allow the surface of the soil to dry between waterings.

Tomato Spotted Wilt

Tomato spotted wilt virus (TSWV) is spread by tiny insects called thrips, which acquire the virus by feeding on one of many infected weeds or ornamental hosts, and then spread it to the developing tomato plants. Several weeks after transplanting the tomato plants into the garden, random plants may appear stunted, and younger leaves may be marked with bronze or dark spots or have prominent purple veins. Often the upper foliage will become twisted and cupped as the bronze areas expand. Fruits may have yellow spots. Younger plants may wilt and die, but older plants may survive and bear discolored fruit that may not fully ripen.

Prevention & Treatment: Eliminating weeds in the garden is the first step in reducing the chance of acquiring TSWV. Keeping the grass and weeds mowed in areas surrounding the garden may reduce the spread of thrips onto susceptible garden plants. Weeds in the garden area during the winter may harbor both the thrips and the virus. For best prevention, remove the old crop debris, till, and then mulch the garden for the winter to keep weeds and thrips down for the next year.

Reflective (aluminum or silver-colored) mulch beneath the tomato plants may reduce the number of thrips that arrive and feed upon the plants. If reflective mulch is not available, paint black plastic mulch silver before transplanting the tomatoes.

There is no cure for a plant with TSWV. Roguing or removing infected plants immediately from the garden may help reduce the incidence of disease on additional plants. However, feeding by thrips can transmit the virus to plants within minutes. Because of this rapid infection time, insecticidal sprays may be of no use for the home gardener.

Seeds of several TSWV-resistant cultivars of tomatoes are available from mail-order seed companies. These cultivars are resistant but not totally immune. They may acquire the virus, but yields and fruit quality may remain acceptable. Look for cultivars with resistance if this has been a problem in the past. See Table 5 below for recommended TSWV-resistant cultivars.

Tomato Yellow Leaf Curl

Tomato yellow leaf curl virus (TYLCV) is not seed-borne but is transmitted by whiteflies. This disease is extremely damaging to fruit yield in both tomato and pepper crops. Whiteflies may bring the disease into the garden from infected weeds nearby, such as various nightshades and jimsonweed. After infection, tomato plants may be symptomless for as long as 2 to 3 weeks.

Symptoms in tomato plants are the upward curling of leaves, yellow (chlorotic) leaf margins, smaller leaves than normal, plant stunting, and flower drop. If tomato plants are infected early in their growth, there may be no fruit formed. Infected plants may appear randomly throughout the garden. Pepper plants may also become infected, but will show no symptoms.

Prevention & Treatment: Removal of plants with initial symptoms may slow the spread of the disease. Rogued (pulled out) infected plants should be immediately bagged to prevent the spread of the whiteflies feeding on those plants. Keep weeds controlled within and around the garden site, as these may be alternate hosts for whiteflies. Reflective mulches (aluminum or silver-colored) can be used in the rows to reduce whitefly feeding.

Low concentration sprays of a horticultural oil or canola oil will act as a whitefly repellent, reduce feeding and possibly transmission of the virus. Use a 0.25 to 0.5% oil spray (2 to 4 teaspoons horticultural or canola oil & a few drops of dish soap per gallon of water) weekly. Examples of products containing horticultural oil are:

Bonide All Seasons Spray Oil Concentrate

• Ferti-lome Horticultural Oil Spray Concentrate
• Monterey Horticultural Oil Concentrate
• Southern Ag Parafine Horticultural Oil
• Summit Year Round Horticultural Oil Concentrate

At the end of the season, remove all susceptible plants and burn or dispose of them. See Table 6 for tomato cultivars with resistance to Tomato yellow leaf curl virus.

Other Viruses

Different viruses cause different symptoms on tomatoes. Symptoms of virus infection may appear as light and dark green mottling of the leaves. Tobacco mosaic virus (TMV) causes a mottling of older leaves and may cause the malformation of leaflets, which may become shoestring-like in shape.

Viruses are highly infectious and readily transmitted by any means that introduces even a minute amount of sap from infected into healthy plants.

Prevention & Treatment: There are no chemical controls for viruses. Remove and destroy infected plants promptly. Wash hands thoroughly after smoking (the Tobacco mosaic virus may be present in certain types of tobacco) and before working in the garden. Eliminate weeds in and near the garden. Control insects (thrips and whiteflies) that carry viruses (see HGIC 2218, Tomato Insect Pests).

Rotate tomatoes with crucifers (such as cabbage, broccoli, and turnips). Use reflective mulches. Use virus-resistant tomato cultivars. Many cultivars have Tobacco mosaic virus (TMV) resistance (the letter T follows the cultivar name), such as Bush Celebrity, Bush Early Girl, Jetsetter, Big Beef, Celebrity, Sweet Cluster, Sweet Million (cherry), and Super Marzano (paste).

Root-knot Nematodes

Root-knot nematodes (Meloidogyne species) are microscopic worms that live in the soil and in plant roots. Affected plants are usually stunted, discolored, and may die. Knots or galls develop on the roots.

Prevention & Treatment: When nematodes are not yet present, move the tomato crop to a different area within the garden every year, purchase disease-free plants, pull up and dispose of roots immediately after harvest, and use resistant cultivars (indicated by N following tomato cultivar name). See Table 7 for cultivars resistant to root-knot nematodes.

When root-knot nematodes are present, relocate the garden to a nematode-free area. Use nematode resistant tomato cultivars. Establish a rotation system using marigold cultivars Tangerine, Petite Gold, or Petite Harmony, which reduce root-knot nematode populations in soils. For more information, see HGIC 2216, Root-Knot Nematodes in the Vegetable Garden.

Disorders

Blossom End Rot: Blossom end rot is a physiological disorder of tomato. Symptoms are water-soaked spots on the blossom end of the fruit. These spots enlarge and become black. Secondary infection by decay-causing organisms usually follows.

The cause of this disorder is a calcium deficiency in the developing fruit. Extreme fluctuations in moisture, rainy or cloudy weather with high humidity, cool temperatures, insufficient soil calcium, root pruning from nearby cultivation, and excessive ammoniacal (NH₄ ⁺) nitrogen, potassium, or magnesium fertilization can also increase the chances of blossom end rot, especially early in the season.

Prevention & Treatment: Late spring planting of tomatoes should be at the recommended date for your area. The soil should be limed according to recommendations of a soil analysis report to bring the soil pH to 6.5 and to provide adequate calcium levels in the soil. Limestone is best applied 3 to 6 months in advance and tilled into the garden soil. Follow the soil report for recommendations for pre-plant nutrient (fertilizer) applications. If calcium levels are not sufficient, but the soil pH is correct, then gypsum (calcium sulfate) is best tilled into the soil before planting at 1 to 2 pounds per 100 square feet.

Avoid excessive potassium or magnesium fertilization as these nutrients will compete with calcium for uptake by the plants. Epsom salt is an example of a magnesium source, so do not apply to garden soil unless a recent soil report indicates a magnesium deficiency.

Avoid ammoniacal nitrogen fertilizers for sidedress applications (beside or around the plants), as ammoniacal nitrogen also will compete with calcium for uptake. Examples of fertilizers with ammoniacal nitrogen are ammonium sulfate, ammonium nitrate, and most complete fertilizers, such as 10-10-10. A calcium nitrate (15.5-0-0) side dress fertilizer is usually the best choice and is applied monthly at 2 pounds per 100 feet of row.

Maintain a uniform supply of moisture through irrigation and adequate soil mulches. Mulches will not only keep the soil cooler and more evenly moist but will suppress weeds, thus reducing the need for nearby cultivation that may damage tomato roots. Remove fruit with blossom end rot symptoms from the plants.

However, if blossom end rot occurs because the soil was not tested and neither lime nor gypsum was applied pre-plant, then the application of gypsum at 1 to 2 pounds per 100 square feet as a sidedress supplement has proven beneficial. See Table 8 for tomato cultivars with resistance to blossom end rot.

Sunscald: Sunscald occurs when tomatoes are exposed to the direct rays of the sun during hot weather. It is most common on green fruit. Decay causing fungi frequently invade the damaged tissue.

Prevention: Cover exposed fruits. Control leaf diseases, as foliage shades the fruit.

Growth Cracks: Tomatoes crack when environmental conditions (drought followed by heavy rain or watering) encourage rapid growth during ripening. Some cracks may be deep, allowing decay organisms to enter the fruit and cause fruit rot.

Prevention: Maintain even soil moisture with regular watering and adequate mulch. Some tomato cultivars are crack-tolerant; see Table 9 for suggested cultivars.

Poor Fruit Set: Poor fruit set occurs for several reasons:

• Extreme temperatures: The blossoms drop off without setting fruit when temperatures are below 55 °F or above 90 °F for extended periods. Try Arkansas Traveler, Talladega Hybrid, Homestead 24, Bella Rosa Hybrid, Top Gun Hybrid, Solar Fire Hybrid, Florida 91 Hybrid, Sioux, or Costoluto Genovese for heat-tolerance.
• Dry soil: Blossoms dry and fall when the plants do not receive enough water.
• Shading: Few blossoms are produced when the plants receive less than six hours of sun a day.
• Excessive nitrogen: High nitrogen levels in the soil promote leaf growth at the expense of blossom and fruit formation. Correct the nitrogen imbalance with superphosphate or 0-20-20 fertilizer.

Catfacing: This is a disorder caused by cold temperatures during fruit set. The fruit is extremely malformed and scarred, usually at the blossom end. Fruits that develop later in the season will not be affected. The cultivar Homestead 24 is resistant to catfacing.

Leaf Roll: Leaf roll of tomatoes may be caused by high temperatures, prolonged periods of wet soil conditions, and drought. It may also occur when tomatoes are pruned severely or when nearby tilling damages roots. The symptom is mostly on older leaves, with an upward curling of the leaflets, but may progress to affect up to 75 percent of the foliage. The rolled leaves may feel leathery and stiff. Often the condition of leaf roll occurs once the plants are under the stress of a heavy fruit set. Some cultivars are more prone to leaf roll than others.

Prevention & Treatment: The symptom of leaf roll does not significantly damage the crop. To help prevent this disorder, tomatoes should be planted on well-drained soil and be irrigated during periods of drought. For more information on physiological leaf roll, please see HGIC 2222, Tomato Leaves Rolling?

Herbicide Injury: Drift from nearby sprays of broadleaf weed killers used on turfgrass, such as 2,4-D and dicamba, and non-specific herbicides, such as glyphosate, may severely damage tomato plants.

Initial symptoms of glyphosate injury on tomatoes are characteristically seen as white/yellow discoloration at the base of the leaflets.

Caution: Pollinating insects, such as honey bees and bumblebees, can be adversely affected by the use of pesticides. Avoid the use of spray pesticides (both insecticides and fungicides), as well as soil-applied, systemic insecticides unless absolutely necessary. If spraying is required, always spray late in the evening to reduce the direct impact on pollinating insects. Always try less toxic alternative sprays first for the control of insect pests and diseases. For example, sprays with insecticidal soap, horticultural oil, neem oil extract, spinosad, Bacillus thuringiensis (B.t.), or botanical oils can help control many small insect pests and mites that affect garden and landscape plants. Neem oil extract or botanical oil sprays may also reduce plant damage by repelling many insect pests. Practice cultural techniques to prevent or reduce the incidence of plant diseases, including pre-plant soil improvement, proper plant spacing, crop rotation, applying mulch, applying lime and fertilizer based on soil test results, and avoiding overhead irrigation and frequent watering of established plants. Additionally, there are less toxic spray fungicides that contain sulfur or copper soap, and biological control sprays for plant diseases that contain Bacillus subtilis. However, it is very important always to read and follow the label directions on each product. For more information, contact the Clemson Extension Home & Garden Information Center.

Table 1. Fungicide Products for Home Garden Disease Control on Tomatoes.

Fungicide Active Ingredient	Examples of Products Containing the Active Ingredient
Chlorothalonil	Bonide Fungonil Concentrate; & RTU1 Ferti-lome Broad Spectrum Landscape & Garden Fungicide Conc. ; & RTU1 GardenTech Daconil Fungicide Concentrate Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide Conc. Ortho MAX Garden Disease Control Concentrate Southern Ag Liquid Ornamental & Vegetable Fungicide Conc. Tiger Brand Daconil Concentrate
Mancozeb	Bonide Mancozeb Flowable with Zinc Concentrate Southern Ag Dithane M-45
Copper Fungicide2	Bonide Copper Fungicide Spray or Dust (wettable powder; 3.98%) Bonide Liquid Copper Concentrate (a copper soap; 1.8%) Bonide Liquid Copper Fungicide RTU1 Camelot Fungicide/ Bactericide Concentrate (a copper soap) (1.8%) Concern Copper Soap Fungicide for Flowers, Fruit & Vegetables RTU1 Espoma Organic Copper Soap RTU1 Monterey Liqui-Cop Copper Fungicidal Garden Spray Concentrate (8%) Monterey Liquid Copper Fungicide RTU1 (soap) Natural Guard Copper Soap Liquid Fungicide Concentrate (1.8%); & RTU1 Southern Ag Liquid Copper Fungicide (8%)
1 RTU products are pre-mixed fungicides in a spray bottle. 2 For copper fungicide concentrates, the greater the metallic copper content, the better the control of bacterial & fungal diseases.

Table 2. Tomato Cultivars with Resistance to Early Blight.

Tomato Cultivar	Other Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Mountain Supreme Hybrid	VF	D	69-70
Mountain Fresh Hybrid	VFF	D	77
Mountain Magic Hybrid	VFF	ISI	72
Plum Regal Hybrid	VFF	D	72
Plum Dandy Hybrid	VF	ISI	82
Cabernet Hybrid	VFF	I	60
Manalucie	FSt	I	82
Merlot Hybrid	VFF	I	59
Tommy Toe (cherry)	none	I	70
Mountain Merit Hybrid (moderate EB resist.)	VFFFN TSWV LB	D	75
Jasper Hybrid (cherry)	FF LB S	D	60
Iron Lady Hybrid	LB S	D	77
Matt’s Wild Cherry (moderate EB resistance)	LB (moderate)	I	60
Juliet Hybrid (mini-roma) (moderate EB resist)	none	I	60
Defiant PhR Hybrid (moderate EB resistance)	VFF LB	D	70
Legend (moderate EB resistance)	LB	D	68
Old Brooks (moderate EB resistance)	LB	I	78

Table 3. Tomato Cultivars with Resistance to Late Blight.

Tomato Cultivar	Other Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Legend	EB (moderate)	D	68
Mountain Magic Hybrid	VFF EB	ISI	72
Plum Regal Hybrid	VFF EB	D	72
Mountain Merit Hybrid	VFFFN TSWV EB (Moderate)	D	75
Jasper Hybrid (cherry)	FF EB S	B	60
Iron Lady Hybrid	EB (moderate) S	D	77
Defiant PhR Hybrid	VFF LB EB (moderate)	D	70
Matt’s Wild Cherry	EB (moderate)	I	60

Table 4. Tomato Cultivars with Resistance to All 3 Races of Fusarium Wilt.

Tomato Cultivar	Disease Resistance*	Plant Growth Habit**	Days to Ripeness
BHN 640 Hybrid	VFFF TSWV	D	75
Charger Hybrid	VFFFASt	D	76
Crista Hybrid	VFFF TSWV	D	73
Floralina Hybrid	VFFFA	D	72
Tasti-Lee Hybrid	VFFF	D	75
Solar Fire Hybrid	VFFF	D	72
Top Gun Hybrid	VFFFSt TSWV	D	75
Mountain Merit Hybrid	VFFFN TSWV EB (moderate)	D	75

Table 5. Tomato Cultivars with Resistance to Tomato Spotted Wilt Virus (TSWV).

Tomato Cultivar	Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Bella Rosa Hybrid	VFFASt TSWV	D	75
BHN 444 Hybrid	VFF TSWV	D	75
BHN 640 Hybrid	VFFF TSWV	D	75
Capaya Hybrid	VFASt TSWV	D	70
Crista Hybrid	VFFF TSWV	D	73
Fletcher Hybrid	VN TSWV	D	74
Health Kick Hybrid	VFFA TSWV	D	74
Plum Regal Hybrid	VFF TSWV	D	72
Sophya Hybrid	VFFSt TSWV	I	75
Talladaga Hybrid	VFF TSWV	D	60-67
Top Gun Hybrid	VFFFSt TSWV	D	75
Mountain Merit hybrid	VFFFN TSWV EB (partial)	D	75

Table 6. Tomato Cultivars with Resistance to Tomato Yellow Leaf Curl Virus (TYLCV).

Tomato Cultivar	Other Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Champion II Hybrid	VFFNTA	I	62-65
Charger Hybrid	VFFFASt	D	76
Margo Hybrid	VFFT	D	70

Table 7. Tomato Cultivars with Resistance to Root-Knot Nematodes.

Tomato Cultivar	Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Beefmaster Hybrid	VFNASt	I	80
Bella Rosa Hybrid	VFFNA	D	75
Better Boy Hybrid	VFNASt	I	75
Better Bush Hybrid	VFN	ISI	68
Big Beef Hybrid	VFFNTASt	I	73
Burpee’s Supersteak Hybrid	VFN	I	80
Bush Early Girl II Hybrid	VFFNT	ISI	54
Bush Goliath Hybrid	VFN	ISI	68
Celebrity Hybrid	VFFNTASt	ISI	70
Champion II Hybrid	VFNTA	I	65-70
Empire Hybrid	VFFNASt	D	72
First Prize Hybrid	VFFNT	I	75
Fletcher Hybrid	VN TSWV	D	74
Goliath Hybrid	VFFNT	I	70
Grandma’s Pick Hybrid	VFN	I	78-80
Jetsetter Hybrid	VFFNASt	I	64
Laroma III Hybrid	VFFNA	D	76
MiRoma Hybrid	VFFN	D	70
Park’s Whopper CR Improved Hybrid	VFFNT	I	65
Royesta Hybrid	FFNT	I	70
Super Fantastic Hybrid	VFN	I	70
Super Marzano Hybrid	VFNTA	I	90
Tiffany Hybrid	VFNT	I	70
Tomande Hybrid	VFFNT	I	68
Tough Boy Hybrid	VFN	I	75
Viva Italia Hybrid	VFFNASt	D	72
Mountain Merit Hybrid	VFFFN TSWV EB (moderate)	D	75

Table 8. Tomato Cultivars with Resistance to Blossom End Rot of Fruit.

Tomato Cultivar	Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Manalucie	FSt EB	I	82
Mountain Spring Hybrid	VFF	D	72
Mountain Fresh Hybrid	VFF EB	D	77
New Yorker	VA	D	66
Ravello Hybrid	VFT	I	60-65
Wins All	none	I	80

Table 9. Tomato Cultivars with Resistance to Cracking.

Tomato Cultivar	Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Abraham Lincoln Original	none	I	87
Aunt Ginny’s Purple	none	I	75-85
Box Car Willie	none	I	80
Campbell’s 33 Hybrid	VFA	D	69
Celebrity Hybrid	VFFNTASt	ISI	70
Charger Hybrid	VFFFASt	D	76
Delicious	none	I	77
Fantastic Hybrid	VF	I	65
Gardener’s Delight	none	I	65
German Head	none	I	80-90
Heinz 1439 Hybrid	VFA	D	70
Juliet Hybrid	LB	I	60
Mountain Spring Hybrid	VFF	D	72
New Yorker	VA	D	66
Pilgrim Hybrid	VFFASt	D	68
Pink Girl Hybrid	VFT	I	76
Plum Regal Hybrid	VFF TSWV	D	80
Porter’s Pride	none	I	70
Rutgers	VFA	D	75
Super Sioux	none	ISI	70
Supersonic Hybrid	VF	I	75-79
Thessaloniki	none	I	75-80
Tough Boy Hybrid	VFN	I	75
Chef’s Choice Orange Hybrid	T Anthracnose	I	75

Table 10. Tomato Cultivars with Resistance to Bacterial Speck.

Tomato Cultivar	Other Disease Resistance*	Plant Growth Habit**	Days to Ripeness
Super Marzano Hybrid	VFNT	I	70-90
Health Kick Hybrid	VFFA TSWV	D	74
Viva Italia Hybrid	VFFNA	D	75
Charger Hybrid	VFFFASt	D	76
Mountain Pride Hybrid	VFFASt	D	77
Marcellino Hybrid	none	I	75-80
Ravello Hybrid	VFT	I	60-65
Tomatoberry Garden Hybrid	none	I	60-70

*Disease Resistance Codes: V Verticillium wilt resistance F Fusarium wilt race 1 resistance FF Fusarium wilt races 1 & 2 resistance FFF Fusarium wilt races 1, 2 & 3 resistance A Alternaria resistance St Stemphylium or gray leaf spot resistance N Root-knot nematode (RKN) resistance T Tobacco mosaic virus (TMV) resistance EB Early Blight resistance LB Late Blight resistance S Septoria Leaf Spot resistance

**Plant Growth Habit Codes: D Determinate plant growth habit (concentrated fruit set) I Indeterminate plant growth habit (fruit set throughout the summer) ISI Indeterminate short internode (a compact growth habit with longer fruit set)

Pesticides are updated annually. Last updates were done on 5/21 by Joey Williamson.

Originally published 09/00