As long as you provide tomato plants with a high quality of soil, correct watering and feeding and plenty of attention, you can expect to be fairly successful. The reason that attention is an important ingredient in tomato plant care is that there are a number of maladies that tend to affect tomato plants.
In this article, we review tomato plant problems and their symptoms. We also provide sound advice to help you avoid and cope with these common challenges. Read on to learn more about why are the leaves on my tomato plants turning brown & more.
What You'll Learn Today
- 10 Problems You Are Likely To Encounter In Tomato Plants
- 1. Why are the leaves on my tomato plants turning brown?
- 2. Why do my tomato plant leaves look soggy, papery and brown?
- 3. Why do my tomatoes have rotten spots on the bottom?
- 4. Why are my tomato flowers falling off before fruiting?
- 5. Why are my tomato plants’ leaves wilting and turning yellow?
- 6. Why are my tomato plants stunted and discolored?
- 7. Why are my tomato plants’ leaves deformed and sticky?
- 8. Why do my tomatoes have white and yellow patches on them?
- 9. Why are my tomatoes cracking and splitting?
- 10. What causes yellow leaves in tomato plants?
- Other Questions
- What diseases are the most likely culprits when tomato plant leaves turn brown?
- What ailment should you suspect if older lower leaves on your tomato plants begin to develop brown or black spots?
- What does it mean when brown spots on tomato leaves are surrounded by a yellow circle?
- What if the brown spots on my tomato plant leaves are surrounded by a yellow halo but don’t have any fungal growth in the center of the brown spot?
- How can you identify spotting on tomato leaves that is caused by Oomycete pathogens?
- How are blight diseases different than simple leaf spotting diseases?
- Will leaf spotting caused by Anthracnose negatively impact tomato fruit?
- How do environmental factors affect leaf spotting in tomato plants?
- What steps should gardeners take to manage fungal leaf spot on tomato plants in home gardens or on small farms?
- What does the term “start clean and stay clean” mean in reference to tomato gardening?
- Final Words
10 Problems You Are Likely To Encounter In Tomato Plants
1. Why are the leaves on my tomato plants turning brown?
Early in the season you may see brown or black spots on your tomato plant leaves. This is followed by dropped leaves and/or sunburned fruit. These are all symptoms of Early Blight, which is a fungus that lingers in leaf litter through the winter and is present to attack young tomato plants early in the growing season.
To avoid Early Blight, it’s important to clean up old tomato plants at the end of the season. Pull up the spent plants and get all of the dead leaves, roots and vines out of your garden before winter begins. Don’t compost dead tomato plants. Instead, throw them into the trash or burn them.
In addition to removing decaying tomato plants from your garden at the end of the season, you should also practice crop rotation. Don’t plant your tomatoes in the same place year after year. This is an open invitation to the fungus that causes Early Blight.
2. Why do my tomato plant leaves look soggy, papery and brown?
Another type of fungus causes a different type of blight in tomatoes. Late Blight is active toward the end of the growing season when the plants may be larger and more crowded in your tomato patch.
Warm, wet weather encourages the development of Late Blight. Lack of good air circulation caused by overcrowding facilitates its growth. There is no cure for Late Blight. If your plants are struck with it, you must simply pull them up and dispose of them in the trash or burn them.
To avoid the development of Late Blight, keep your plants properly pruned so that they can dry out quickly after heavy rains. Rotating your crops every year will also help prevent this problem.
If your plant is producing plenty of tomatoes, but the fruit never fully matures without developing mushy brown spots on the bottom that then transition to black, you are dealing with Blossom End Rot.
This problem is caused by uneven moisture and/or calcium deficiency. To prevent it, water your tomatoes on a regular schedule. Never allow the soil around them to become excessively dry or soggy. If you notice that your plants are wilting, adjust your watering schedule to correct the problem.
If the soil around your tomato plants is consistently moist, and you feel that your watering schedule is correct, you may be dealing with calcium deficiency. Get in touch with your county extension agent and have the soil tested.
If the pH level of the soil is too high or too low, or if there’s too much nitrogen in your soil, these conditions will interfere with your plants’ ability to take up calcium.
If your soil is too acidic, you may need to amend it with lime and/or leaf compost. If the soil is too alkaline, amend with a low nitrogen, high phosphorus fertilizer. It’s wise to talk with your county agent regarding exactly what steps to take in your situation.
4. Why are my tomato flowers falling off before fruiting?
If you’re experiencing unpredictable weather with great fluctuations in temperature, your plants may develop Flower Dropsy.
This is a condition that happens when there is a difference of more than 40°F between daytime and nighttime temperatures. For example, if your daytime temperatures are 95°F or higher, and your nighttime temperatures are 75°F or lower, Blossom Drop will result.
Hot, dry winds can also cause this problem. This is because your plant will drop its flowers to help retain moisture.
Sadly, there’s not a lot you can do about this. You might try tossing a sheet over your plants at night to protect them against chill. Providing some shelter from the wind may also be helpful.
5. Why are my tomato plants’ leaves wilting and turning yellow?
Wilting, yellowing leaves – especially on only one branch of the plant – indicate fungal infection. There are two incurable fungal infections that affect tomato plants. They are Verticillium Wilt and Fusarium Wilt.
Verticillium Wilt causes mature leaves to turn yellow between the veins. Fusarium Wilt causes the leaves of a single branch to turn yellow and wilt.
Sadly, there is nothing you can do about these conditions. If your plants exhibit these symptoms, you should pull them up, put them in plastic bags and put them out with the trash or burn them.
You can avoid these infections by choosing varieties of tomato plants that are bred to resist these fungal infections. Additionally, remember to rotate your crops every year.
6. Why are my tomato plants stunted and discolored?
If the soil around your plant is infested with pest nematodes, they will feed on the roots and cause them to swell up. This causes plants to become stunted, and it causes the leaves to become discolored.
Tomato plants affected by bad nematodes will still produce tomatoes. Just continue to care for them as you normally would. Planting marigolds around the affected plants may help drive the nematodes away. Remember to plant marigolds in your tomato patch right from the start in years to come.
Identifying And Treating Tomato Diseases
7. Why are my tomato plants’ leaves deformed and sticky?
Tiny pests such as spider mites and aphids can cause your plants leaves to be shiny, sticky and deformed.
Aphids leave a substance called honeydew on the leaves of the plants they infest. This sweet, sticky, shiny substance attracts ants, so if you see lots of ants traveling up and down your tomato plants, suspect that aphids are in residence.
Spider mites leave a coating of fine web over plants’ leaves. This causes a sticky feel to the leaves.
Both aphids and spider mites suck the sap out of your plants and cause leaf deformity.
To prevent having these pests set up housekeeping on your plants, be sure to keep your tomato patch well weeded. It’s also a good idea to encourage predatory insects such as ladybugs to live in your veggie garden. They will make short work of these tiny pests.
If you do already have an aphid and/or spider mite infestation, knock the pests off your plants with a blast of water several days in a row. Follow-up with a horticultural soap treatment. Once you have the infestation under control, introduce some ladybugs into your garden.
8. Why do my tomatoes have white and yellow patches on them?
We’ve already talked about white spots on tomatoes. If your tomato fruits are over-exposed to the sun, they will develop sunscald. To prevent this happening, be careful not to become overzealous with pruning. Your tomato plants need enough leaves to provide shade to the fruit.
9. Why are my tomatoes cracking and splitting?
If you get a lot of rain after a long, dry period, your tomatoes may swell suddenly and split or crack. Alternately, if you allow your fruit to stay on the vine too long, it will become overripe and it will crack.
To prevent this problem, harvest your tomatoes before the heavy rain. Be sure to inspect your tomatoes regularly and pick them as needed throughout the growing season.
Note that cherry tomatoes tend to crack very easily, so you need to keep a close eye on them.
If you’re inspecting your tomatoes every day and you find some split or cracked fruit, you can go ahead and harvest them and eat them. If they haven’t been hanging on the vine for a long time, damaged, they should still be just fine.
10. What causes yellow leaves in tomato plants?
There are a number of reasons why the leaves on your tomato plants may begin to turn yellow. Some are just normal development, and some are problems.
Toward the end of the summer, determinant plants will begin to die. These types of plants are only intended to live through one growing season. When that time is up, they will turn yellow and die.
If it’s early in the season, and you see that the leaves at the bottom of your plant are turning yellow, it may signal a nitrogen deficiency. If this is the case, get in touch with your county extension agent for a soil test to be sure.
If your soil is low in nitrogen, you may need to amend it with well rotted compost or manure. Alternately, you could use an organic vegetable fertilizer that is rich in nitrogen.
You can prevent yellowing leaves in the years to come by amending your soil in advance of the growing season.
What diseases are the most likely culprits when tomato plant leaves turn brown?
Browning of tomato leaves may be caused by a number of common diseases, such as:
- Septoria blight or leaf spot caused by Septoria lycopersici
- Late blight caused by an Oomycete pathogen
- Anthracnose caused by Colletotricum spp
- Early blight caused by Alternaria solani
- Tomato spotted wilt (TSWV)
- Bacterial leaf spot
What ailment should you suspect if older lower leaves on your tomato plants begin to develop brown or black spots?
This type of leaf spotting can be an early sign of early blight. It’s important to step in before the ailment can spread upwards on the plant.
What does it mean when brown spots on tomato leaves are surrounded by a yellow circle?
This type of leaf spotting on tomato plants is most likely caused by Septoria. If you see tiny, dark fruiting bodies (fungal growth) at the center of the brown spot, your problem is surely Septoria.
What if the brown spots on my tomato plant leaves are surrounded by a yellow halo but don’t have any fungal growth in the center of the brown spot?
This could be an indication that the brown spots are caused by a bacterial infection rather than a fungus. If the spots appear very quickly and look more like water spots, suspect bacterial infection.
How can you identify spotting on tomato leaves that is caused by Oomycete pathogens?
This type of damage usually happens very late in the season (i.e. late blight). The dark spots caused by Oomycete pathogens are large and greasy looking. They spread very rapidly over leaves and stems.
How are blight diseases different than simple leaf spotting diseases?
The pathogens that cause early or late blight in tomato plants wreak havoc on the health and well-being of the entire plant. Oomycete pathogens and Alternaria solani have the ability to spread rapidly through plant tissues causing the breakdown and death of entire systems. This is the meaning of the term, “blight” in reference to plant illness.
Will leaf spotting caused by Anthracnose negatively impact tomato fruit?
Yes, this fungal leaf disease very easily spreads to tomatoes as they develop and can have a very negative impact on the harvest. To avoid this, be sure to provide a healthy culture for your plants with well-draining soil, good air circulation and staking to prevent leaf contact with soil.
How do environmental factors affect leaf spotting in tomato plants?
Environmental stresses can lead to the spread of disease. It is also possible for environmental stresses, such as excessive heat or lack of water to cause leaf damage problems such as leaf roll or simply dry, crispy leaves.
What steps should gardeners take to manage fungal leaf spot on tomato plants in home gardens or on small farms?
As with all plants, disease prevention relies heavily on keeping a vigilant eye on your crops. Remove damaged and/or diseased foliage the moment you see it. Leave plenty of space between plants to allow for good air circulation and ample sunlight. Prune your plants as needed, and provide protection against harsh, inclement weather.
What does the term “start clean and stay clean” mean in reference to tomato gardening?
This is a wise term that can be well applied to all sorts of gardening. Careful plans and cautious decisions go a long way toward preventing the onset and spread of disease in the garden. To start clean and stay clean, follow these guidelines:
- Apply fungicides to foliage in a preventative manner according to label instructions.
- Use mulches to lower humidity among plants and reduce the chances of infection.
- Choose clean, healthy plants to begin with.
- Use clean seed. Rotate crops each season.
- Remove weeds and volunteer plants.
- Practice good sanitation
I hope you’ve found this guide useful! If you have any questions or comments, please use the section below. If you are looking for more answers about typical tomato pests, here is our guide on tomato hornworms.