Most tomato growing problems are preventable by regularly fertilizing and watering the plants. They vary in severity, but there usually are methods to treat all of them. To make the most out of this resource, use the search function (Ctrl+F) to look for a particular symptom. Note that all the symptoms associated with a particular problem are listed under the problem name.
Blossom End Rot
Syndrome: Black, leathery rot at the bottom of the fruit that enlarges as the fruit mature. The rot starts off as just a water spot, but soon starts increasing in size and darkness.
Causes: Calcium deficiency
Solution: Water and fertilize plants on a regular schedule, and do not overdo either. Consider mulching to stabilize moisture level in the soil. This problem most often occurs when trying to grow big planted varieties (especially paste tomatoes like Roma) in containers that are too small. Some growers like to add crushed eggshells to the transplant hole to fortify calcium intake.
Early Blight
Syndrome: Black-brownish spots on plant leaves; leaves drop off; sunburned fruits
Causes: Fungal infestation
Solution: Clean up the growing environment, like weeding or mulching. When watering, try not to splash mud onto the plant. Also note that the fungus that causes this tomato plant problem can live over winter, so be sure to clean up any infested plant leaves immediately. Also, try not the plant tomatoes in the same spot next year.
Fusarium Wilt
Syndrome: Wilted yellowish, brown leaves; discolored roots; discoloration inside of plant stem
Causes: Fungal infestation
Solution: There are no effective fungicides for this type of fungal infestation. Remove infected plants completely along with any residues from the garden and avoid growing tomatoes in the same spot next year. Many hybrids varieties are bred for resistance against this common tomato growing problem. They’re labeled by the letter ‘F’.
Mosaic Virus
Syndrome: Yellowish tomato leaves; stunted plant growth
Causes: Cucumber Mosaic Virus
Solution: There are currently no effective solutions for controlling this tomato plant problem. Remove the plants along with any residues from the garden, and avoid planting in the same spot next year.
Nematodes
Syndrome: Swelling of the plant roots; stunted plants; discolored plant leaves
Causes: Soil-borne microscopic worms
Solution: Plants infested with nematodes can still survive and produce. Once the growing season ends, remove the plants from the garden. Try choosing nematode-resistant varieties (marked by the label “N” after the variety name). An organic treatment for nematodes involves blanketing the planting area with Marigolds for an entire growing season. Chemicals released by Marigold roots are known to kill nemadoes.
Phospherous Deficiency
Syndrome: Dwarfed plant growth; thin stems; curly, droopy leaves with a purplish stint
Causes: A common tomato growing problem early on in the season, especially during cold weather, which hinders phosphorous uptake by the plants.
Solution: Use red plastic mulch to help warm up the soil. This problem should disappear once the temperature of the soil rises.
Septoria Leaf Spot
Syndrome: Plant leaves develop thin, papery spots that are grayish in color
Causes: Fungal infestation
Solution: Clean up the growing area by mulching, weeding, etc… Copper sprays may be effective at stopping the infestations.
Tomato Hornworms
Syndrome: Chewed up plant leaves and damaged fruits that are still unripe
Causes: This is a pest problem- tomato hornworms are large, green-grayish caterpillars that feed off of tomato fruits and plants.
Solution: Pick off by hand
Verticillium Wilt
Syndromes: Dry, yellowish leaves; browning of leaf veins starting with older, lower leaves
Causes: Fungal infestation
Solution: Remove infested plants and residues from the garden and avoid growing in the same spot next year. Verticillium Wilt is another common tomato growing problem that modern hybrids are well protected against. Protected hybrids are labeled ‘V’ (after their variety names).