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Tomato - Diseases, Pests and Problems





Basic Information



Problem: Flea Beetle
Affected Area: Leaf and Root

Description: Tiny holes ?pinholes? chewed in leaves by adult insect. Adult insects are 1/16" long, hard shelled, shiny, dark-colored beetles that jump when disturbed. Slender, whitish, cylindrical larvae feed in or on roots but root damage is generally minimal. They generally do not do much harm in themselves but may spread diseases.

Control: Keep debris removed. Rotate location of planting from year to year. Dust with *Rotenone * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Tomato Horn Worm
Affected Area: Leaf and Fruit

Description: Large green caterpillar with a color that typically matches plant. Has diagonal lines on their sides. Has a long ?horn? protruding from its tail. Ranges from 1" to 4" long and 1/4" to 1/2" thick. They have a voracious appetite and can quickly strip a plant of all its leaves and may also eat fruit. They leave black droppings below affected plants.

Control: Frequent inspection and hand picking is the best protection unless the plants become severely infested. Spray with BT, Bacillus Thuringiensis, in the form of dipel or thuricide. Insects will stop eating within a few hours and finally die.


Problem: White flies
Affected Area: Leaf and Fruit

Description: Small (1/8" long) moth-like white fly in plant. Actually neither moth nor fly, they are related closely to aphids and scale. White flies feed on plant sap and leave a sticky substance on leaves and fruit. Although white flies are a major problem in greenhouses, and less of a problem in gardens in the past, they have become more of a problem in gardens in recent years. May be numerous late in the season and rise up in clouds when plant is disturbed. May reduce yield.

Control: No excellent control currently available. Uproot and dispose of plants in garbage at end of season to avoid over-wintering eggs. Spraying with insecticidal soaps will help control these pests.


Problem: Verticillim, Fusarium and Nematodes
Affected Area: Entire plant

Description: Foliage is blighted and wilts Plants wither and die

Control: Plant resistant varieties that have VFN appended to the name on the package. Do not sprinkle late in the day. Rotate tomato plantings yearly.


Problem: Tobacco Mosaic
Affected Area: Leaf

Description: Mottled leaves. Plant becomes sickly and dies

Control: If you use tobacco, do not handle plants without washing thoroughly with soap. Do not smoke around tomato plants. Destroy affected plants


Problem: Curly Top
Affected Area: Leaf

Description: Caused by a virus. Leaves curl and twist upward and foliage becomes leathery, yellows and dies. Veins become purplish and dominant. Plants are stunted, fruits ripen prematurely while small without developing sweet flavor. Disease is spread by beet leafhopper.

Control: Overplant slightly to allow for some loss of plants. Destroy affected plants. Rotate planting location


Problem: Blossom End Rot
Affected Area: Fruit

Description: Round, leathery spot on blossom end of fruit. May be slightly sunken. Affects green as well as ripe fruits, but is more common in ripe fruits Is a physiological disorder caused by water imbalances caused by irregular watering or over-watering especially early in the season. Is very common in heavy clay soils.

Control: Water uniformly rather than allowing the plant to experience wet, dry, wet, dry cycles. Water tomato wetting the soil to 24" deep. Mulch to stabilize soils against evaporation. Large temperature fluctuations can stimulate it. A change in summer weather patterns may correct the problem.


Problem: 2-4,D injury
Affected Area: Leaf

Description: Leaves emerging when 2-4,D is used as an herbicide on nearby plants, become curled and twisted with veins taking on a parallel pattern. Older leaves may turn yellow or browned.

Control: Tomatoes are highly susceptible to 2-4,D damage and may be affected by drift and volatilisation from some distance away. Avoid spraying lawn areas adjacent to gardens and avoid spraying when temperatures are expected above 85? F within the next few days.


Problem: Catfacing and cracking
Affected Area: Stem and Fruit

Description: Catfacing is circular cracks in rings around the blossom end of the fruit and cracking is perpendicular to the stem at the stem end. These are a result of fast growth caused by high temperatures and moisture levels, initial fruit growth during a dry spell followed by heavy rains or watering or excessive swings in day and night temperatures. Radial cracks form as hot weather dehydrates the fruit slightly. When water arrives in the form of rain or sprinklers, the fruit absorbs moisture so rapidly that it swells and then the skin cracks.

Control: The changes are purely cosmetic, but may be diminished by using resistant varieties such as ?Big Beef.? Avoid sprinkle irrigation.


Problem: Sunscald
Affected Area: Fruit

Description: White areas on fruits due to damage by sun exposure. Sunscald is localized damage to the tissue.

Control: Prevented by a good foliage cover.


Problem: Anthracnose
Affected Area: Leaf and Root

Description: This disease is characterized by small, slightly depressed, circular lesions that appear on ripened fruit, although they may have infected the fruit before it began to ripen. The leaves also develop lesions that are small, circular, and brown surrounded by yellow halos. The plants root system becomes extremely damaged by brown lesions and no longer can support the plants needs so it shuts down.

Control: The best form of control is to control the weeds in the field, apply fungicide sprays, and stake the plants and practice good mulching habits.


Problem: Aphids
Affected Area: Leaf

Description: Plants that are suffering from aphids have yellow spots, distorted leaves, are stunted, wilt, and the blossoms fall off. The aphids consume more plant juices than they need and excrete the excess as a sugary substance called honeydew resulting in reduced photosynthesis and fruit quality.

Control: N/A


Problem: Bacterial Spot
Affected Area: Leaf, Stem, and Fruit

Description: This disease is characterized by brown, circular spots that develop on the leaves, stems, and fruit scars. Fruit lesions begin as small, slightly raised blisters and as a spot increases in size it becomes brown, scablike, and slightly raised.

Control: The best form of control is to rotating fields to avoid carryover crop residue, produce disease-free transplants, use seed treatments, and apply bactericides or fungicide-bactericide combinations where recommended.


Problem: Bacterial Wilt
Affected Area: The above ground portion of the plant

Description: This disease is characterized by wilting of the youngest leaves and if the disease progresses, the whole plant will quickly wilt. By suspending a clean section of the diseased stem in water, it is possible to detect this specific disease from other vascular diseases. After 3-5 minutes, a white, milky stream of bacterial cells and slime flow from xylem elements of the infected plant.

Control: The best forms of control include crop rotation, applying soil fumigants and using pathogen-free soil. There are only a few cultivars that offer resistance and they should be used when possible.


Problem: Boron Deficiency
Affected Area: Leaf and Fruit

Description: Plants that are suffering from boron deficiency have brittle leaves, the lower leaf tips turn yellow and the terminal growing point dries up. The fruit on these plants develop corky areas around the stem end, open locules, and uneven ripening.

Control: N/A


Problem: Calcium Deficiency
Affected Area: Leaf

Description: Plants that are suffering from calcium deficiency have undeveloped leaves at the growing point, yellow and marginal drying in between the veins, and the growing point dies.

Control: N/A


Problem: Catface
Affected Area: Fruit

Description: This disease is characterized by large scars and holes in the blossom end of the fruit. The fruit is often in distorted into a variety of shapes with elongated blossom scars.

Control: The best form of control is to use resistant cultivars and do not over water the plants.


Problem: Chlorine Deficiency
Affected Area: Leaf

Description: Plants that are suffering from chlorine deficiency grow slow, have dry leaf margins, and the leaves fall off.

Control: N/A


Problem: Copper Deficiency
Affected Area: Leaf

Description: Plants suffering from copper deficiency have young leaves that wilt and become yellow and dry.

Control: N/A


Problem: Early Blight
Affected Area: Leaf, Stem, and Fruit

Description: This disease is characterized by small, dark, slightly sunken stem lesions on seedlings that develop into small brownish black lesions on older foliage. The fruits also exhibit symptoms which include a leathery skin that may be covered with a velvety mass of black spores.

Control: The best form of control is to use resistant cultivars and by spraying regularly with fungicides.


Problem: Flea Beetles
Affected Area: Leaf

Description: These are small beetles, about one sixth of an inch long, that mainly attack seedlings. They may be black, brown, greenish or yellow and leave small holes on the leaves of attacked plants.

Control: N/A


Problem: Fusarium Wilt
Affected Area: Leaf

Description: This disease is characterized by drooping and downward curling of the older leaves which turn yellow. Also, seedlings become stunted if infected.

Control: Using resistant cultivars is the best form of control.


Problem: Gray Leaf Spot
Affected Area: Leaf

Description: This disease is characterized by small, barely visible, brownish black specks that develop on the lower leaves and then the leaves turn brown, die rapidly, and drop.

Control: The best form of control is to use resistant cultivars and spray with fungicides.


Problem: Hornworms
Affected Area: Leaf and Fruit

Description: Hornworms have a distinctive horn on the rear end. They will completely defoliate a plant leaving only the stems. They may eat some fruit leaving gouged areas where they were eating.

Control: N/A


Problem: Iron Deficiency
Affected Area: Leaf

Description: Plants that are suffering from iron deficiency have areas of yellow between the veins on young leaves. These areas initially develop near the leaf base and gradually progress to the leaf tip.

Control: N/A


Problem: Magnesium Deficiency
Affected Area: Leaf

Description: Plants that suffer from magnesium deficiency are characterized by yellowing between the veins of the oldest leaves and gradually moves to the younger leaves.

Control: N/A


Problem: Manganese Deficiency
Affected Area: Leaf

Description: Plants that suffer from manganese deficiency show yellowing of tissue between the veins on younger leaves and are followed by the development of dry areas between the veins. The leaf veins remain their green color.

Control: N/A


Problem: Molybdenum Deficiency
Affected Area: Leaf

Description: Plants rarely suffer from molybdenum deficiency but symptoms of the deficiency include yellowing and marginal drying of older leaves that later progress to the younger leaves.

Control: N/A


Problem: Nitrogen Deficiency
Affected Area: Leaf and Fruit

Description: Plants suffering from nitrogen deficiency appear yellow beginning with the youngest leaves and progressing to the older leaves, which become yellow and drop off. If too much nitrogen is applied, there will be an excess amount of top growth with little fruit production.

Control: N/A


Problem: Phosphorus Deficiency
Affected Area: Leaf

Description: Plants that are suffering from phosphorus deficiency have a purple color on the undersides of the leaves in the veins and gradually extends out to the interveinal areas. The growth on the plant may have stopped giving it a dwarfed appearance and the upper leaves may take on a dull or light green to yellow coloration.

Control: N/A


Problem: Potassium Deficiency
Affected Area: Leaf

Description: Plants suffering from potassium deficiency usually have marginal drying of older leaves. The drying is preceded by scattered small, yellow areas near the leaf margin, which enlarge, group together, and finally dry out.

Control: N/A


Problem: Rhizoctonia Diseases
Affected Area: Seed

Description: This disease is characterized by seedlings that may fail to germinate or established plants that develop a fungus near the soil line with a brown, reddish brown or black lesion.

Control: The best forms of control include using good quality seed, fungicide applications, and chemical or heat pasteurized planting medium. The best way to prevent fruit rot losses is to prevent direct contact of the fruit with the soil under warm, moist conditions.


Problem: Southern Blight
Affected Area: Stem

Description: This disease is characterized by a brown to black rot of the stem, which develops near the soil line. The lesions develop rapidly, completely girdling the stem and resulting in a sudden and permanent wilt of all aboveground parts.

Control: The best forms of control include crop rotations with nonsusceptible grass crops and the use of protective fungicides.


Problem: Spider Mites
Affected Area: Leaf

Description: Plants that have been attacked by spider mites have small, yellow spots on the upper surfaces of leaves where the mites have been feeding. The lower surfaces of the leaves are covered with silken threads which is a characteristic symptom. As the population density of the mites increase, they move to the top leaves, where they produce large amounts of silk webbing.

Control: N/A


Problem: Sulfur Deficiency
Affected Area: Leaf

Description: Plants suffering from sulfur deficiency initially have light green younger leaves and as the deficiency progresses the older leaves also turn light green.

Control: N/A


Problem: Thrips
Affected Area: Entire Plant

Description: Plants that are infected with thrips have damaged tissue that initially appears silvery but may turn dry or black and flower parts, particularly the pistils, become damaged and may cause bloom abscission. It must be noted that bloom abscission is associated with a number of nutritional, environmental and physiological disorders and that it is not singly associated with thrips.

Control: N/A


Problem: Whiteflies
Affected Area: Leaf and Fruit

Description: Plants that are infected with whiteflies develop yellow spots, yellowing of the leaves, spots on the fruit, stunting, and wilting of plants. The aphids consume more plant juices than they need and excrete the excess as a sugary substance called honeydew resulting in reduced photosynthesis and fruit quality. The damage is inflicted by whiteflies that consume more plant juices than they need and excrete the excess as a sugary substance called honeydew resulting in reduced photosynthesis and fruit quality.

Control: N/A


Problem: Zinc Deficiency
Affected Area: Leaf

Description: Plants suffering from zinc deficiency have thick leaves that curl downward and faint interveinal yellowing.

Control: N/A






Tomato

Tips

Tomatoes will ripen off the vine with good quality if picked after color shows.

 

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