The 16 Most Common Tomato Plant Problems
Even if you aren’t an avid gardener like I am, it’s hard to deny this one simple fact:
Homegrown tomatoes taste better.
Therefore, it’s no surprise that this is the most popular plant for large-scale gardeners and weekend warriors alike to grow in their garden plots.
While tomatoes are relatively easy to grow, there are some challenges in producing healthy tomato plants that can frustrate even the most experienced of gardeners.
In our area, for example, we’ve had an exceptionally cold and wet spring. That made it difficult to get our transplants into the ground on time, and once we did, we found that they were extremely stunted for the first few weeks.
Luckily, they seem to have caught up, and are doing fine now (albeit growing a bit more slowly than they normally would).
Keep an eye on your tomato plants this season to make sure you don’t have to worry about one of these common tomato plant problems decimating your crop.
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What Are Common Problems With Tomato Plants?
Tomato plants may suffer from a variety of issues, such as pests, nutrient deficiencies, and diseases, all of which I’ll take a closer look at in this post:
Insects like aphids, whiteflies, and beetles can cause damage to tomato plants.
Viral and fungal diseases can spread easily among tomato plants, leading to foliage discoloration and stunted growth.
Too much or too little water and insufficient sunlight can also lead to unhealthy tomatoes.
Here’s a video so you can learn more:
What Are Common Causes of Tomato Plant Problems?
Here are some issues to be aware of:
Over or Under Fertilizing
Too little fertilizer can damage your tomato plants, particularly if they’re already growing in nutrient-deficient soil. Adding an organic fertilizer, like compost, at the time of planting as well as supplementing with regular worm tea or worm castings can help keep them healthy. Some diseases can be prevented or treated by supplementing with certain nutrients, such as calcium.
Always do a soil test (here's a link to an inexpensive yet effective soil test kit) before planting so that you know where your soil stands. Keep in mind that sometimes, too much fertilizer can harm your tomatoes, too. You may not notice it at first.
For example, if you are fertilizing with a nitrogen-only fertilizer, it may seem as though your tomato plants are thriving, putting on tons of luscious green growth. However, they will likely struggle to set and ripen fruit, as all of the plant’s energy is being spent on foliage.
Therefore, moderation is key when it comes to fertilizing. I recommend using a fertilizer like this one by Nature Hills Nursery that is formulated specifically for tomatoes and their particular growing needs.
Over or Under Pruning
Pruning is a great way to increase airflow and reduce the likelihood of disease and pest infestation, but there is such a thing as too much pruning, too. Tomatoes need some leaves to conduct photosynthesis.
Ample leaves can also protect the fruits from poor weather. Familiarize yourself with the correct methods of pruning tomatoes and use a tomato staking system or tomato cage to provide a support system both before and after pruning tomatoes.
Calcium Deficiency
Technically a nutrient deficiency, I consider calcium to be a category all its own. Calcium is incredibly important in preventing and treating diseases in plants.
Your pH should be held at roughly 6.5 and you can apply lime or gypsum to improve calcium content. You can also add natural amendments like crushed eggshells when you transplant your tomatoes to boost calcium in the soil.
Inappropriate Planting Times
This is the one that gets me every time. During my first year of growing tomatoes, I planted them way too late (I think it was mid-July by the time they got in the ground). We had a minimal harvest because our first frost is usually in mid-October - they simply don't have enough time to grow.
Scarred by this past experience, I now get a bit overzealous in the spring. As a bad habit, we always start our seeds indoors too early, and because the plants get leggy and outgrow their containers indoors, I feel the urge to get them in the ground in mid-May. This is too early where I live, not necessarily because it’s not warm enough yet, but because the ground is too wet.
Long story short, make sure you're planting your tomatoes at the time that is appropriate to your area’s specific hardiness zone. Knowing when to plant tomatoes can really make the difference between a so-so and dynamite harvest.
And for goodness sake, stick to it!
Improper Watering
Water your plants too much, and the roots will rot. Water them too little, and your fruit will be hard and dry - and your plants will wilt. Try to provide at least two inches of water per week during the growing season.
If this is not produced via natural rainfall, use an irrigation system that helps prevent disease and improves infiltration. I recommend soaker hoses, but if you don’t have the means to implement these, try to mulch heavily around your plants so that they can retain water during dryer times of the year.
Remember that overhead watering is an acceptable method of watering your plants, but that tomato plants whose leaves become damp will dry slowly, particularly if you water at night. This can encourage the growth of fungus and cause your plants to rot.
Lack of Oxygen
Too little oxygen flow can also spur fungal growth. Try to space your tomatoes several feet apart so that they have good circulation and apply fungicide if you notice powdery mildew.
What Are the Most Common Tomato Problems - and How Can I Treat Them?
1. Blossom End Rot
What is it?
This disease causes small black spots on the bottoms of otherwise healthy tomatoes. You can cut off the spots, but the fruit of the tomato will still have an odd taste.
How can I prevent and treat it?
Blossom end rot is usually caused by a lack of calcium. Low soil pH can also be to blame. Testing your soil prior to planting can help reduce the likelihood of this disease. Make sure the pH is around 6.5 and add calcium if your pH is not ideal. Organic compost with crushed up eggshells can also prevent this disease.
If blossom end rot becomes a problem during the growing season, create a foliar spray that contains calcium chloride. Spray it on your plants every morning, before the sun had fully risen.
2. Bacterial Canker
What is it?
Bacterial canker looks like white spots on tomatoes that are just about ripe. If there is a dark ridge around these spots, you will know it is bacterial canker and not another similar disease. This is one of the most unpleasant tomato problems to deal with, as it’s spread by a specific type of bacteria, Clavibacter michiganensis.
How can I prevent and treat it?
Practice good garden hygiene. The bacteria responsible for this disease is usually introduced via contaminated tools. It can also be spread by contaminated tomato seeds or rainwater. Avoid injuring your plants. If you must prune your tomatoes, make sure you are doing so with sanitized tools.
I also recommend wearing gloves. I am the worst about losing my gardening gloves, so I usually end purchasing inexpensive ones like this from the Dollar Tree.
You can also rotate crops thoroughly between seasons to prevent the bacteria from gaining a foothold. If you discover bacterial canker in the garden, dispose of the infected plants. Do not place them in your compost, as they can reinfect your garden in later years.
3. Fruit Cracks
What is it?
Fruit cracks look like concentric circles on your fruit. While these aren’t harmful in themselves and they don't cause any ill effects to your tomatoes, they do provide a gateway to hungry birds and bugs who want to snack on your fruit. This disease is caused by uneven watering habits following a prolonged period of dry weather.
How can I prevent and treat it?
Practice good watering habits. Know that your plants will absorb water very quickly if there are heavy amounts of rain following hot and dry weather, which will cause the fruit to expand and crack. Keep your plants moist yet not too wet at all times.
4. Sunscald
What is it?
Sunscald is most commonly found on plants with ripe fruit. It is caused by exposure to the hot rays of the sun, which “scalds” the fruit and creates white or yellow spots. It is mostly cosmetic, but can also affect the flavor of the fruit.
How can I prevent and treat it?
Avoid excessive pruning and remember that some of the leaves help to shelter the fruit from the sun. Using shade cloth can help during the hottest portions of the growing season.
5. Blossom Drop
What is it?
As the name implies, blossom drop is when plants grow plenty of flowers, but these flowers fall off before they can create fruit. This disease is most common when temperatures fluctuate rapidly.
Because tomatoes tend to grow best at temperatures between 55 and 75 degrees Fahrenheit, they don’t like when conditions are not stable. This illness can also be caused by inappropriate levels of nitrogen, poor pollination, and insect damage.
How can I prevent and treat it?
Only transplant healthy plants and avoid transplanting unhealthy seedlings. Make sure your planting location is ideal, with exceptional drainage and lots of sunlight.
Too much wind can also be to blame, so keeping your plants sheltered can help. Cover the tomatoes if cold weather is expected. You can also add pollinators and avoid using chemicals as these kill off beneficial pollinators.
The best method of treating blossom drop is to prevent it. Because this condition won’t affect your plants, addressing the previously mentioned environmental factors is usually enough to turn your plants around.
6. Poor Fruit Set
What is it?
When plants develop excessive amounts of flowers and too few tomatoes, you likely have poor fruit set. This is caused by excessive levels of nitrogen in the soil, which encourages leaf growth, but not fruit development.
How can I prevent and treat it?
Avoid overfertilizing - always conduct a soil test before you add any amendments to the soil. You should also make sure your plants are not crowded. If they are too crowded, they will not be able to pollinate themselves sufficiently. Encourage pollination by gently shaking the leaves of the plants when they are in flower.
7. Catfacing
What is it?
The name is entertaining, but when you discover catfacing on your tomatoes, you definitely won’t be laughing. This disease causes your tomatoes to look lumpy and bumpy. It’s not clear what, exactly, causes this issue, but usually disturbing the buds or flowers can be a cause, as can damage from herbicides.
How can I prevent and treat it?
Wait to plant the tomatoes until the weather has warmed. When periods of cold weather are expected overnight, cover your tomatoes. You can cover the ground surrounding the tomatoes with black plastic, which will absorb sunlight during the day and insulate the plants overnight.
8. Leaf Roll
What is it?
Leaf roll happens only to mature plants. This causes a plants’ leaves to curl inward This usually attacks the leaves of a plant, but it usually does not impact the development of fruit.
How can I prevent and treat it?
Avoid excessive pruning and try to keep your watering habits consistent. Tomatoes that are exposed to too-wet or too-dry soil can be susceptible to leaf roll. Make sure your tomato plants are grown in light, well-drained soil.
9. Puffiness
What is it?
Puffiness usually is not noticed by the average gardener until he or she cuts into a tomato. The Inside of the plant will be hollow, and while you may notice a lightness to the fruits when you pluck them from the vine, you probably won’t notice the difference until it is unfortunately too late.
How can I prevent and treat it?
Puffiness is usually caused by poorly fertilized soil, but too much or too little fertilizer can be too blame. Poor pollination or too much water can also be to blame. Make sure you are amending the soil with balanced organic compost every few weeks and top-dress occasionally with compost tea.
10. Septoria Leaf Spot
What is it?
Septoria leaf spot tends to affect the bottom leaves of young plants only. This causes yellow spots on foliage, which later develop into darker gray bad spots. The affected leaves ultimately fall off.
How can I prevent and treat it?
Caused by a fungus, this disease can be spread by overhead watering. Water from the ground and apply a fungicide like Certis Double Nickel which can eliminate septoria Leaf spot very quickly.
11. Anthracnose
What is it?
This disease looks shockingly similar to blossom-end rot. However, instead of producing even black spots, you will notice a circle that is shaped more like a bull-eye. This spot will be sunken and soft, and will result in rotted black fruit inside the tomato. Caused by a fungus known as Colletotrichum phomoides, this disease thrives in hot, wet weather.
How can I prevent and treat it?
Implement good watering techniques, such as soaker hoses instead of overhead irrigation. This will reduce the spread of the fungus. You should also harvest your tomatoes as soon as they have ripened to allow the fungus less time to take hold.
12. Early Blight
What is it?
Early blight causes brown spots on tomato leaves. Most common in mature plants, early blight is a gardener's worst nightmare. Foliage will eventually fade to a yellow color before the leaves fall off and die. Plants may be bare.
How can I prevent and treat it?
Caused by the fungus Alternaria solani, this disease can overwinter, so if you have problems with it one year, you’ll likely have it in later years, too. Rotate your crops every year so that the fungi cannot thrive. Make sure you don’t plant crops like eggplant and peppers near your tomatoes, as these can also be affected by early blight.
13. Late Blight
What is it?
Late blight is a disease that affects gardeners who are growing potatoes and growing tomatoes alike, and can quickly destroy an entire crop. This disease can cause a total loss of crops and is caused by a fungus. If a plant is infected, it must be immediately destroyed.
How can I prevent and treat it?
Prevent late blight by choosing resistant varieties. While there are no tomato species that are completely immune to late blight, there are some that are better at fighting it off.
You should also rotate your crops and provide plenty of space between your tomatoes to improve airflow and prevent cross-contamination. Avoid watering from above and do not compost infected plants.
14. Powdery Mildew
What is it?
This disease is yet another fungus that can infect your plants. This is a common disease in most gardens, affecting everything from tomatoes to zucchini. It looks like a white, lightweight powder coating the stems and leaves of your plant, and if left untreated, can cause the foliage to yellow and brown.
How can I prevent and treat it?
This disease is caused by poor airflow and too much water. While it is more common in plants that are growing in greenhouses or hoop houses, it can be found everything. Give your tomatoes lots of room and remember to prune. Again, practicing good irrigation techniques can prevent this disease, too.
15. Fusarium Wilt
What is it?
Fusarium wilt causes rapid witing on tomatoes as well as other similar plants. This disease sets in quickly, with tomato plants appearing to be fine one day and then totally wilted the next.
How can I prevent and treat it?
This disease is worsened by watering, which is unfortunate as many gardeners assume (and not incorrectly) that a wilted tomato plant is simply one that is thirsty. This disease is caused by a fungus that resides in the soil, so rotating your crops on a yearly basis can help prevent it from gaining a foothold. You can also purchase wilt-resistant varieties of tomatoes.
16. Verticillium Wilt
What is it?
Verticillium wilt causes yellow spots on the bottom leaves of plants. It causes the plants’ leaves and stems to be killed off or stunted.
How can I prevent and treat it?
Verticillium wilt lives in the soil. Practicing crop rotation can help to protect your plants, as can purchasing wilt-resistant cultivars. In some cases, you may be successful using a fungicide.
Common Tomato Plant Pests
Cutworms
What are they?
Cutworms aren’t actually worms, so their name is a bit of a misnomer. These creatures are actually the larvae of moths, and they’ll come out after dark to nibble on your seedlings. They munch right through the stems at soil level, meaning they can quickly decimate your entire crop.
How can I prevent and treat them?
To prevent cutworms from ruining your harvest, surround each seedling with a ring made out of cardboard or plastic. This will help block off access to the cutworms.
Hornworms
What are they?
Also known as tobacco worms, tomato hornworms are large caterpillars that blend in well with your tomato plants. These bugs are aggressive, eating mature tomato plants in a matter of a night.
How can I prevent and treat them?
Treat your plants with Bacillus thuringiensis if hornworms are a problem. This is a natural bacteria that won’t harm your plant, but can get rid of hornworms as well as other common pests, like beet armyworms. Beneficial insects, birds, and mammals that prey on hornworms can also be attracted by growing a pollinator garden.
Potato beetles
What are they?
Potato beetles are attracted to all plants that are nightshade vegetables, which includes tomatoes, eggplants, and potatoes. These yellow bugs have black stripes and will eat the leaves of all of your nightshade plants in a matter of hours.
How can I prevent and treat them?
You can use pyrethrin or neem spray to get rid of the adults as well as the larvae of these pests. You can also manually remove them by shaking the leaves and allowing the creatures to fall to the ground. Drown them in soapy water to eliminate them entirely.
Spider Mites
What are they?
Spider mites are tiny, often going unnoticed in a garden. However, they do plenty of damage, gathering on the leaves and sucking the juice out of them. They leave behind scars that can later inhibit the growth of your tomato plants.
How can I prevent and treat them?
Use a neem oil spray or insecticidal soap to get rid of spider mites. You can also introduce ladybugs to your garden.
Birds
What are they?
Birds aren’t the only non-insect pests that will eat tomatoes - lizards, deer, chipmunks, and other animals will also eat tomatoes - but they are perhaps the most common regardless of where you live. Most of these creatures usually won’t eat the stems and leaves of your plants, but they’ll love chowing down on the fruits.
How can I prevent and treat them?
Early in the season, you don't need to do much to deter these pests - they won’t usually get in your garden until the fruits have set. However, sturdy netting and other physical barriers can help prevent animals from enjoying your tomato buffet.
Don’t Be Intimidated
The easiest way to prevent and eliminate tomato plant problems in your garden is to familiarize yourself with your plants. Get to know them so that it’s easier to figure out what’s going on.
Identify the affected part of the plant, be it the roots, stems, leaves, blossoms, fruit - or all of them. Compare your damaged plants to the healthy ones, and check your plants daily for insect damage.
What other tomato plant problems have I missed? Be sure to let me know in the comments.
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