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Totally Tomatoes Part 6 – Recognizing Tomato Problems

What’s wrong with my plants? Trying to figure that out can be challenging. Here are a few common problems you might run into and be able to correct.



The Tobacco Horn Worm (above) and Tomato Horn Worm (below) are fairly common. They are often mistaken for each other and both love to munch on tomato plants. Most often you will not see him until you see the damage he has done to some of the leaves on your plant. Once you see the damage, go on the hunt. As awful as it may seem, look for his poop – he will be on the leaves directly above. Remove him and feed him to the birds or frogs (a favorite of both).


If he has these white Q-tip looking cocoons hanging off his body, he’s no longer a threat to your plant.

Tomato-Hornworm with cocoons

Those are the cocoons of a tiny Braconid wasp (a good guy), and this caterpillar is now the host food for those immature wasps. If you allow the wasps to finish their life cycle, they will help control any future horn worms in your garden and they don’t sting people.


Why do my plants look like they are dying when it’s still summer. Late in the season tomato plants are not supposed to look good – they are working on producing and ripening the fruit rather than growing the plant. This is how nature intended the life cycle to be. BUT make sure you’re not looking at a disease or cultural problem that might kill the plant before it has time to produce ripe fruit. Here are two good photo diagnostic links:







Problem Cause Solution
Leaf Curl Too much fertilizer Flush with water or transplant
Yellow Lower Leaves    
in seedlings Not enough light or magnesium deficiency Supply more light/add magnesium
in mature plant Plant may be transferring energy into producing fruit Remove lower leaves
  Can sometimes be Early Blight  
Leggy Growth Not enough light or too warm air temperature  
Bud Drop/no fruit forming Air too dry and hot Patience
Leaf Discoloration   Add balanced fertilizer – 1/2 dilution
pale green Nitrogen deficiency  
red/purple undersides Phosphorus deficiency or pH to low  
bronze leaf edges Potassium deficiency or over watered  
Leaf Spots with White spores Late Blight Remove entire plant before it infects others
Discolored Roots Excess salts (too much fertilizer) Flush with water or transplant
Mold Growth on top of soil Poor drainage, too low pH Re-pot seedlings in fresh soil-less mix
Damping Off   Remove infected seedlings
Prevent first Good air circulation, water from bottom, use fine milled sphagnum moss as top dressing  
Poor Root Growth Poor soil aeration, poor drainage, phosphorus deficiency Replant in soil-less mix
Poor Germination Improper soil temperature, seeds planted too deep, soil dried out after seed began to swell, no firm contact between seed and soil, poor seed Check germination requirements
Split Fruit Skin Inconsistent watering Mother Nature has this one
Blossom End Rot Calcium deficiency – often caused by excessive pruning or fluctuation in moisture  
Dry white patches on fruit Sunscald – too much sun or not enough sun cover on the hottest days  
Pithy Watery Fruit Too much water as fruit is maturing Pick fruit that has started to ripen after a rain storm and allow to finish ripening inside


Click HERE to help recognize the difference between diseases and an environmental issues.

All these possible problems may lead gardeners to believe that growing tomatoes is more work than it’s worth. Not so! Most often plants survive and still produce fruit even if they become diseased, over watered or are eaten by bugs. The best way to have a truly successful tomato harvest is to prevent problems before they start. Prepare your soil well, keep your plants healthy with proper feeding, consistent moisture, and good air circulation. And a great preventative is to apply a foliage spray of kelp every month.

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