How to Identify and Treat
Tomato Plant Problems

Numerous tomato plant problems exist that must be dealt with, even though tomatoes are considered one of the easier plants to grow.

From microscopic organisms to creepy crawly bugs, it seems like there is always something out there just waiting to ruin your hard work!

Don't fret - there is hope for the diligent and concerned gardener, and we’re here to help you combat several of the common tomato plant problems that can occur.


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Tomato Plant Diseases and Pests

Use these images to identify your problem (bigger versions are below). Click images to jump to a tomato plant pest or disease:

Tomato Hornworms

Tomato Hornworms

Tomato Pests, including aphids, cutworms

Other Tomato Pests and Bugs

Tomato blight on tomatoes

Tomato Blight and other Tomato Plant Diseases

Tomato plant diseases: septoria leaf spot

Septoria Leaf Spot

Tomato Rot

Tomato Rot

Tomato Wilt

Tomato Wilt

Tomato Hornworm

Hornworms can cause serious tomato plant problems and should not be taken lightly. These things will eat the leaves, stems, and the fruit, and then move onto the next plant!

Tomato Hornworm

Photo used under a Creative Commons licence with the kind permission of BugMan50 and Flickr

Tomato hornworms are rather large, but because of their light green color, they are easy to miss, but the damage they can bring will be evident.

Because hornworms are so big, the easiest way to take care of them is by simply pulling them off your tomato plant (it's an organic solution!).

If the problem calls for a tougher fix, Bacillus thuringiensis (BT) spray is great at killing hornworms during their caterpillar stage, and is safe for use on food crops.

Not only do these pesky pests eat tomato plants, they'll also attack eggplants, potatoes, and pepper plants. Watch out!

Tomato Hornworms grow quite large, and can devastate crops

Photo used under a Creative Commons licence with the kind permission of ilovebutter and Flickr

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Please also see our page on Tomato Plant Care.

Tomato Pests

Besides tomato hornworms, several other pests exist that create tomato plant problems. Aphids, cutworms, bugs and beetles (not the ones that want to “Hold Your Hand”) all pose a threat to your delicate tomato plant.

Aphids are tiny green bugs that can slowly eat away at your tomato plant. They often come in large numbers, but due to their light green color, blend in easily.

To relieve your tomato plants of an aphid invasion, remove the foliage where the aphids have congregated and throw away in a closed container.

If the invasion has spread, your best bet may be spray a solution of water, natural or castile liquid soap, and oil. This solution is harmless to your plants yet makes it hard for the aphids to breathe.

Tomato pests: aphids can be washed off with a hose

Photo used under a Creative Commons licence with the kind permission of Waldo Jaquith and Flickr

Another great (and organic) cure for aphids is ladybugs! These little things, while cute and harmless to us, are actually aphids' number one predator.

Cutworms are nasty little gray worms that like to chew on the stems and leaves. Worst of all, they do must of their munching at night! Inspect your plants' stems and leaves in the evening, and if damage is present, it's time to take action.

A simple solution has been created specifically for preventing cutworms – cutworm collars.

Tomato Pests, including aphids, cutworms

Photo used under a Creative Commons licence with the kind permission of Waldo Jaquith and Flickr

Use pieces of foil or cardboard to make a 4-inch circular barrier that extends all the way around your tomato plant's base. Bury this about an inch into the ground with three inches surround the base. This will prevent cutworms from climbing up.

There is also a commercial plant collar on Amazon (click for more information). You can see what this product looks like below.

These plant collars protect your tomato plants from pests like Cutworms

If it's too late for that, spray a pesticide onto the ground and the main stem of the tomato plant. Spreading a little diatomaceous earth onto the soil will also kill cutworms.

Several types of beetles can wreak havoc on your tomato plants, but the solution is typically the same: Pull the little critters off and drop into a bucket of water.

If the problem is beyond that, beetle pesticide sprays exist, such as Bonide Beetle Killer.

Tomato pests: either spray for beetles, or pick them off

Photo used under a Creative Commons licence with the kind permission of hardworking hippy and Flickr

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Tomato Plant Diseases

Rainy weather, combined with high temperatures and humidity, can lead to a number of tomato plant problems, such as specific tomato plant diseases and fungal infections.

While the weather is uncontrollable, many remedies exist to help alleviate a sick tomato plant.

Tomato Blight

Blight is a fungal infection characterized by small, black lesions that appear on the plant's stems and foliage.

Here are the tell-tale stem problems:

Tomato blight on tomato plant stems

Photo used under a Creative Commons licence with the kind permission of Scot Nelson and Flickr

Here's what happens when the fungal infection spreads to the fruit:

Tomato blight on tomatoes

Photo used under a Creative Commons licence with the kind permission of Scot Nelson and Flickr

And if the blight continues to advance, then your hard-grown tomatoes will end uplooking very sad:

Tomato blight on tomatoes

Photo used under a Creative Commons licence with the kind permission of rubber slippers in italy and Flickr

The area around the spots may turn yellow as time goes on. This infection can spread over to the fruit, making it inedible.

The only real "cure" for blight is to cut off the limb to save the patient. This won't always work: an infected plant is often lost.

However, you can at least try. Remove any signs of blight and dispose of the cutoffs in the garbage. Do not compost blighted tomato plants, as the compost will have the spores.

Treating with tomato plant fungicide may also help.

Septoria Leaf Spot

Septoria leaf spot is a disease characterized by brown spots that usually appear on the foliage closest to the ground.

Unlike blight, septoria won't produce a yellow ring and the best news is, it won't damage your precious fruit.

tomato plant diseases: septoria leaf spot

Photo used under a Creative Commons licence with the kind permission of verymom and Flickr

Proper fertilizing, weeding, debris removal and use of resistant tomato strains usually helps prevent these diseases. Remove infected foliage with pruners and place in the garbage – not on the ground.

Ensure you clean your pruners with rubbing alcohol. A good rule to remember is to avoid getting the foliage wet during watering – try to aim the water only towards the soil.

Some experts also recommend rotating the planting site every year. If these problems persist, many commercial fungicides and are available, such as sulfur powder, Maneb, and Mancozeb.

Tomato Rot

You worked hard all summer long to grow some great tomatoes, and just when you're getting ready to pick that round red fruit, you see it... rot!

Tomato rot is one of the most common tomato plant problems and it will simply ruin your day. Luckily, like most problems, there are preventative techniques.

While it may not seem obvious, the number one cause of tomato rot is due to a calcium deficiency.

Tomato rot: blossom end rot is caused by a calcium deficiency

Photo used under a Creative Commons licence with the kind permission of Scot Nelson and Flickr

Just like humans, plants need calcium to survive. When a fruit or vegetable is deprived of calcium, its tissues break down, thus resulting in the dreaded rot. Too much ammonium sulfate, excess moisture, and low phosphorous levels can cause a calcium deficiency.

You can prevent tomato rot by enriching your garden with organic compost, especially egg shells. Bonemeal is also a great source of calcium, and if you're really in a pinch, crush up some Tums or antacids, as these are rich in calcium.

However, once rot appears on a tomato, there's no going back – you'll have to throw the tomato out.

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Other tomato growing container gardeners will thank you!

Tomato Wilt

There is no surer of a sign that something is wrong than a wilting plant. Tomato wilt is one of the most serious tomato plant problems and can be a heartbreaking sight for any gardener.

Several factors can cause tomato wilt, such as over-watering, lack of water, or infection.

Tomato wilt is heartbreaking. It can be caused by too much water -- or not enough!

Photo used under a Creative Commons licence with the kind permission of Nociveglia and Flickr

It can be hard to tell if you're giving your tomatoes too much water, or not enough, because the signs and symptoms can be nearly the same.

As a general rule, a tomato plant needs about one inch of water a week. If this rule doesn't seem to cure the wilting, the problem may lie elsewhere.

Tomato wilt as a result of infection is characterized by a sudden wilt, but the foliage is still green.

Adjusting the water regimen won't cure the problem.

Here is a picture of Fusarium tomato wilt:

Fusarium tomato wilt is a tomato plant disease, rather than a watering problem

Photo used under a Creative Commons licence with the kind permission of aaronlk and Flickr

Fusarium wilt and verticillium wilt are caused by fungi that live in the soil. With this type of wilt, the leaves and stems will wilt from the bottom up.

Here is what verticulum wilt looks like:

Verticulum tomato wilt is a tomato plant disease, rather than a watering problem

Photo used under a Creative Commons licence with the kind permission of graibeard and Flickr

Once either of these fungal tomato wilt types takes hold, there isn't much that can be done, other than pulling the plant and throwing it in the garbage (not on the ground or in your compost).

Fungal infection prevention techniques (see above) can help eliminate this tomato plant problem. Treating with tomato plant fungicide may also help.


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