Nine Common Tomato Problems

I am serious when it comes to my tomato patch. I know I'm not alone in that sentiment. I've learned that maximizing soil quality and paying attention to my tomatoes daily will yield the best crop. I've compiled my hit list of the 9 most common tomato maladies to watch for since forewarned is forearmed!

#1 Blights – the Quasimodos of Tomato Pathology!

Tomato Blight

Early Blight is a fungus that survives the winter on old vines and then rears its ugly head on your new plants. You will know it's Early Blight when you see blackish-brown spots on the leaves, leaf drop off or see "sunburned" fruit. The best solution is to clean up old vines when the season ends, dispose of in the trash and don't add it to compost pile. Rotate your planting areas and space the plants to allow for good air circulation.

Late Blight starts with leaves that appear water-soaked later turning brown and papery. The fungus is normally present when the weather is very wet enabling the spores to travel far infecting large areas. Like Early Blight, Late Blight is also preventable by rotating your crops annually and by maintaining good air circulation around your plants. If you think that you have Late Blight, same treatment – discard infected plants in the trash and don't compost.

#2 Blossom-End Rot

blossom end rot tomatoes

Blossom end rot sounds like it should be terminal, but a tomato plant can usually pull itself out of this nosedive. The rot looks like pale, brown spots that turn black and flatten the bottom of the fruit due to a lack of calcium or uneven moisture. Lesson is, reduce extreme swings in moisture – avoid allowing them to wilt or overwatering tomato plants. If you don't think fluctuation in moisture is the cause, get your soil tested. Too much nitrogen or soil that is too acidic or alkaline will limit the plant's ability to absorb nitrogen. Lime will sweeten the soil and composted leaves will make it more acidic. Use a fertilizer that is low in nitrogen and high in phosphorous.

#3 Flower Dropsy

Flowers that form but drop before fruiting indicates that your weather is fluctuating too much. If the nighttime temperatures drop below 55°F or if the daytime temps are higher than 95°F with nighttime temperatures that don't drop below 75°F, this can trigger blossom drop. Hot drying winds can intensify the problem. If the plant is not blooming during these periods, you have nothing to worry about however, if your flowers are dropping mulch to maintain moisture.

#4 Fusarium and Verticillium Wilt

No, this is not the next zombie movie the 'tweens are watching. Both of these wilting conditions are caused by an incurable fungal infection – sadly, it's just as deadly as being stuck in a Night of the Living Dead. Once a plant has either one, you should dispose of the plant immediately, do not add to the compost pile. Fusarium Wilt makes the leaves on one branch of the infected plant start wilting and yellow. Verticillium Wilt is yellowing between the major veins on mature leaves. Next year, select a tomato variety that is resistant to wilt.

#5 Bad Nematodes

Yikes! Like a ghost, this varmint is virtually invisible. Resembling some creature from the Black Lagoon - these microscopic eelworms are soil-born, so there is no "cure" for them. They infest the roots causing them to swell. The only aboveground symptoms are stunted plants and discolored leaves. Fortunately, your tomato plants will still bear edible fruit, but once you've discovered the culprit, you will have to wait to address the problem. A common fix is to simply plant marigolds to repel them.

#6 Shiny, Sticky & Deformed Leaves

Shiny, sticky & deformed leaves - no it's not the name of your child's garage band. It's the usual calling card from an aphid, whitefly or spider mite attack. Ghoulish aphids suck the plant sap and excrete a sticky substance on the leaves and fruit. Look for the small, pear-shaped insects congregating on the top growth or on the undersides of the leaves. They can be green, yellow or blackish. Spider mites make small yellow specks and spin fine webs on the leaves, making them feel sticky. Whiteflies will fly up like a cloud when you brush the plant. Keep your tomato plants well-weeded but to overpower them you need reinforcements from a horticultural soap.

#7 Sunscald

tomato sunscald

Sunscald is what we all get when we sit exposed and unprotected for hours outdoors not being sensible about our UV ray absorption. Happens to tomatoes too! Your tomatoes may show yellow or white patches facing the sun. To prevent sunscald grow them in cages where they will produce protective foliage.

#8 Tomato Skins Splitting or Cracking

tomato cracking

Not pretty but definitely the lesser of the other 8 evils mentioned here because the fruits are still edible. Cracking or splitting happens because of sudden growth spurt from an increase in moisture after a dry spell. It can also occur when the fruit is overripe. Provide even moisture and choose plant varieties that are less prone to cracking. Cherry tomatoes are the guiltiest so pick them when they are ripe or almost ripe and/or just before a predicted rain storm to prevent cracking.

#9 Yellow Leaves

Yellow leaves, depending on where you are in the summer season can spell trouble, or not. Late in the season, it's just the tomato shutting down. If early on in the season you notice yellow, uncurled leaves at the bottom of the plant that work their way up - that can signal a nitrogen deficiency or leaves turning yellow or brown higher up on the plant could be early blight.

It's best to do a soil test to determine if it is a nitrogen deficiency. Depending on the soil test result, you may need to supplement the soil with well-rotted manure or compost, both of which are high in nitrogen. You can also apply a nitrogen-rich organic vegetable fertilizer.

Next year, proper soil preparation prior to planting, with good organic material or compost, will prevent this condition.

Good to Know

For a comprehensive reference for the other 99-problems that can happen with tomatoes, see the Guide to the Identification of Common Problems divided into these seven categories: Tomato Disorders, Green Fruit, Ripe Fruit, Insect Pests, Leaf, Stem and Root -- full of imagery to help further diagnose your tomato troubles. Please go to http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver.

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