Tomatoes are by far the most popular of all vegetables for home gardens and are easy and fun to grow. They are, however, susceptible to diseases and insects like all other plants. This is especially true during rainy seasons.

The planting row or area must be fast draining as their root system can not take soggy, wet soil. During dry spells water thoroughly when you water, but not too often. It's also a good practice to avoid overhead watering in favor of either flood irrigation or soaker hoses. Prevention of disease and insects is always the best. Weekly treatments of all your vegetables with preventive insecticides will normally take care of your insect problems. See our Information Centers for current pesticide recommendations.

Also be aware of changes in environmental rulings that affect the production and availability of pesticides. Several classes of pesticides are under scrutiny now and will be for many years to come. Always check with a Cornelius Texas Certified Nursery Professional for the latest and most effective pesticide for your problems. The following are a number of diseases that appear on tomato plants and fruit in our area.

Bacterial Speck
(Pseudomonas)
Seen mostly in cool and moist weather, look for round, dark brown to black spots on leaflets, stems or fruit. These spots may be slightly raised when first observed. Control by crop rotation, sanitation and bactericides where recommended.

Early Blight
(Alternaria)
Late Blight
(Phytophthora)
Although different diseases, both cause leaf, stem and fruit spots progressing to rots. The diseases are favored by humid conditions and can occur at any stage of the plant's growth. Regular fungicidal treatments during the growth and production of your tomato plants will keep the diseases under control, as will proper sanitation and refuse disposal.

Fusarium Wilt
Races 1 and 2
Plants grown from seed appear stunted and transplants eventually exhibit yellow lower leaves (often on one side of the plant). This progresses to wilting during the hottest part of the day until the plant eventually dies. The development of resistant varieties has all but eliminated the concern over this destructive tomato disease.

Gray Leaf Spot
(Stemphylium)
This disease affects only the leaves and appears as minute, barely visible, brownish black specks on the lower leaves. These are circular to oblong and scattered randomly across the leaf surface. As they enlarge, these specks will join together forming larger spots, turning brown, drying up and the centers will often crack in various patterns. Again, regular fungicide sprayings will help prevent infection and the use of resistant varieties has controlled this disease.

Nematodes
Many types of these microscopic worms will cause damage to tomatoes, characterized by stubby roots, knotted roots and a general lack of plant vitality. Planting resistant varieties is the best way to avoid nematodes. If you must plant a susceptible variety, there are very few nematicides available to the home gardener. Our Cornelius Texas Certified Nursery Professionals can suggest the most current ones.

Southern Blight
(Sclerotium)
This disease also affects many plants other than tomatoes. Most of the symptoms begin at the soil level. Plants of any age may be attacked. Seedling symptoms resemble damping off where the dead spot appears at the soil line, causing the seedling to fall over. On older stems the spot begins as a slightly yellow sunken spot. As the disease develops, you will see tan to reddish brown, spherical "spore sacs" on the fuzzy fungus mat on the soil. Several controls have proven effective for the home gardener including good sanitation practices, soil "solarization" with polyethylene sheeting, physical stem barriers of aluminum or plastic, fungicides at transplant time, high calcium and ammonium type fertilizers, and the use of resistant varieties.

Tomato Mosaic Virus &
Tobacco Mosaic Virus
This strange disease causes malformation, curling, mottling and yellowing of leaves. Fruit may show uneven ripening and be reduced in size and numbers. There are no cures for viruses in plants, so choose tomato varieties with resistance to this disease. Good cultural practices include insect prevention and hand washing after the use of tobacco products prior to handling tomato plants.

Verticillium Wilt
Similar to Fusarium Wilt, this disease causes wilting during the day but recovery at night. Characteristic V-shaped yellow areas appear from the leaf margin narrowing toward the midrib. Stems cut lengthwise will show a brown discoloration where the water conducting tissue has died. The only control for Verticillium is the use of resistant varieties. Good garden sanitation will help prevent overwintering and further infection.

White Mold
(Sclerotinia)
This fungus is usually seen at flowering time and is more prevalent during cool weather. Water soaked areas can develop where flowers have fallen and lodged, with the ultimate drying of the tissue that resembles animal bones dried in the sun. Some white cottony fungus growth is often seen on the stem and could be incorrectly identified as Powdery Mildew. Broad-spectrum fungicides applied regularly usually prevent this disease from becoming established.

Pests

Aphids
You will usually see these green or brown round insects feeding on the newest growth and excreting sugary honeydew on the leaves. Regular washing of the leaves in the morning or the use of preventive insecticides will offer good control.

Caterpillars and Fruit Worms
Ranging from tiny to very large, worms eat leaves, stems and fruit on your tomatoes. Often the damage has been done by the time you find them. Using preventive insecticides or biological Bacillus spray are adequate to control.

Leaf Miners
These are small worm-like bugs that work between the upper and lower layer of the leaf, leaving off-colored trails in the leaves. They start on the lower leaves on tomato plants and work upward until they cover the entire plant. At first sign of the leaf miner, spray with preventive insecticides three times at five-day intervals.

Spider Mites
Almost microscopic, these tiny insects feed initially on the underside of the leaves, then migrate to the top of the plant as their population increases. You'll see fine webs of silken strands that are also used in migration as they float or "balloon" from one plant to another. Control Mites by spraying the plants completely with Insecticidal Soap sprays or preventive insecticides.

Thrips
Slender elongated insects, Thrips feed by rasping at the leaf surface and sucking out the juices from ruptured cells. They cause silvery areas on the leaves, premature fruit drop and catfacing in mature fruits. The use of preventive insecticides is adequate to control Thrips.

True Bugs
Stinkbugs and their relatives are the culprits here. Their piercing mouthparts cause spots on developing fruit that result in distorted, deformed and low quality tomatoes. Preventive insecticides are usually adequate to control them.

Whiteflies
Look for tiny white insects that fly around your plants when you disturb them. Primary symptoms of Whiteflies include honeydew on the leaves, light green spotting and yellowing of the leaves, spotting of fruit, and the stunting and wilting of plants. When interplanting tomatoes with many ornamental plants, Whitefly populations can become uncontrollable if undetected. In our area Whiteflies are difficult to control. Prevention is the best control, so begin a regular insect spray program early in the year and continue throughout the growing season.

The following are some of the physical disorders on tomato plants and fruit in our area.
Blossom Drop
The usual cause of Blossom Drop is plant stress. It can be attributed to environmental factors (low or high temperatures, high relative humidity, excessive wind), improper nutrition (deficient fertilizer or excessive nitrogen), and diseases and insects. Heat tolerant tomato varieties have been developed that offer some satisfaction, but general plant health is the best advice.

Blossom End Rot
This looks like a light tan, water soaked area that enlarges and blackens into a leathery and often moldy spot at the point where the blossom was attached to the fruit. It is often attributed to irregular watering, but calcium deficiency has also been identified as an agent. Other factors that reduce calcium uptake also cause this problem, like high salts in the soil, the use of ammonium nitrogen, and high relative humidity. It also seems to happen more likely in rapidly growing plants. Again, general plant health seems to avoid this problem with proper fertilization and water control.

Catface
Catfaced tomatoes are generally misshapen, with enlarged scars and holes in the blossom end of the fruit. Elongated scars appear in kidney-shaped fruit and can be distorted into other shapes. Mostly large-fruited varieties are affected by this problem. Cold weather, pruning and high nitrogen have all been identified as factors contributing to catfacing.

Cracking
When the skin of the tomato fruit is weak or brittle, cracking can develop. You can get concentric circular cracks or radial cracks from the top of the fruit toward the bottom. Several factors seem to contribute to cracking, including plant succulence from high nitrogen, low potassium nutrition, excess rain, wide fluctuations in temperatures, and fruit that is exposed to the sun rather than protected by the foliage.

Sunscald
This appears as dead tissue surrounded by a yellow halo generally on the side or top half of the tomato. It occurs when the fruit is suddenly exposed to sunlight due to careless pruning or harvesting. Defoliation due to diseases and insects can also cause sunscald.

Water Wilt
When we experience heavy rains and the soils are super saturated, water wilt results. Damage occurs more rapidly under higher temperatures. Taking care to plant in well-drained soils and cultivation as soon as possible after a heavy rain can lessen this problem.

Yellow Shoulder
This problem occurs when fruit is suddenly exposed to the sun from harvesting or poor pruning. It is not know exactly what the actual cause is, but it is suspected that the chlorophyll in this area is slow to break down as ripening occurs, resulting in a patch that either remains green or eventually turns yellow. Resistant varieties have been developed and prove the best control aside from correct and thoughtful cultural practices.

Zippering
Just like it sounds, a zipper like scar develops on fruit from the stem down to the blossom end. It seems to be a problem with varieties whose pollen bearing structures (anthers) are attached to the fruit wall of a newly forming fruit. It has been noticed that zippering is more pronounced in cooler weather. Your best control is to grow tolerant varieties.

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