Your tomato plant leaves turning brown is an issue that both veteran and new gardeners encounter. The causes vary from as simple as underwatering to dangerous diseases or pests.

Tomato Plants Leaves Turning Brown

If you do not know the cause of your problem, we are here to help you. Read on with us as we discover which is your issue.

Why Do Your Tomato Plant Leaves Turn Brown?

Your tomato plant leaves turn brown due to different reasons, such as underwatering, pests, and contagious diseases. The most common one from them is underwatering. All of the causes are connected in one way or another and correlate with each other

The diseases spread through the fungus and contaminate one part of the plant. Some diseases spread through bacteria. It is important to identify if the disease is bacterial or fungal. Below, we will discuss some of the causes.  

– Underwatering

As stated, underwatering is the most common cause of leaves turning brown. The tomato plant is a good plant to take care of if you are a new gardener. One of the trickiest parts of taking care of the plant is its watering. 

It is a plant that loves water and gets thirsty often. However, it does not mean that it should get water often. The balance between frequency and method of watering is very important to keep track. Underwatering the plant also can lead to wilting and destroying the whole plant. The tomato might not even have a fruit. Even if it blooms, it will be dry and hard.  

– Wrong Fertilization

Another common cause of brown leaves is the wrong fertilizer. Fertilizer is a tool that helps balance the nutrients that a plant gets. Tomato needs the right balance of nitrogen, phosphorus, and potassium, as well as a number of trace minerals. If the fertilizer does not have the right amount of balance, it can lead to our issues. 

Tomato Leaves Turning Brown Problem

The issue with tomato plants can happen because of two fertilization problems. Either the gardener gave a tomato plant too little fertilization or too much. If the nutrients are too low, it can lead to deficiencies in the tomato plant. If it receives too much, the tomato will grow too fast. 

– Contaminated Soil

Contaminated soil is also a common cause of brown plant problems. The petroleum-based products, such as gas fuel or salt can contaminate the plant.  Other toxins can also play their part in contamination. If the soil is filled with the disease-containing organism, it also counts as contamination. 

– Early Blight

Tomato plants turn brown because of various fungal diseases such as late and early Blight and other diseases such as canker and Verticillium Wilt. All these issues can arise whether you are a veteran gardener or not. 

It is important to inspect your tomatoes frequently. This way, it can prevent disease from spreading. It can also save time and energy, as well as the garden in some cases. Inspection will help you to find the disease before it can spread and destroy the plant.

Introduce good parasites to your garden. This way, you can prevent insects from entering your garden. While introducing you to diseases, we will identify if they are fungal-related or not.

Early Blight is a disease from fungus. The name of the fungus is Alternaria Solani. It spreads through the air and creates brown spots throughout the tomato plants. The spot is half-inch and has a tanned center. During the early stages of the disease, it looks like bacterial leaf, which we will discuss later, but it is a very different disease. The disease can lead to very devastating problems. However, if it is in its early stages, it is possible to save it.

– Late Blight

People confuse this disease with the previous disease. It is due to both of them having fungal origins. This disease, however, spreads with the help of the Phytophthora Infestans pathogen. This disease takes over very fast, and in just a matter of hours, it can spread through the whole plant. The symptoms can show in a matter of days.  

It also develops spots. The spots in this disease are in the leaves, stems and fruit. Spots on the leaves start from pale green and quickly turn brown. It can even turn black if it is in extremely humid condition. Stems become brown right after catching the disease. It is active in the late growing seasons, which is due to the fact that the patch is more crowded and full. 

– Canker

The Canker disease is different from the previously mentioned diseases. Firstly, unlike them, the cause of this disease is bacteria, Clavibacter Michidanensis specifically. It is also different because of its danger level. It can kill off the plant quickly. 

Infected leaves become brown and have crunchy edges and large patches. As the disease develops, the leaves become sunken and have dark coloring. They will die afterward. The same thing happens with stems. When the disease spreads, the stems are twisted and cracked. A similar effect happens to fruits. The coloring becomes different, turning light brown with yellow lesions and a yellow halo. 

– Bacterial Leaf Spot 

This is another disease caused by bacteria, which is called Xanthomonas. As the name suggests, it mainly affects the leaves. However, it can also affect the rest of the plant as well as the whole tomato plant patch.

The infected leaves, like the previous disease, have spots. The spots are round, brown and soaked in water. The spreading of the spot correlates with the spreading of the disease. As the disease worsens, it starts to infect the fruit itself. The fruit starts to have springy and brown dots. The leaves, most of the time, turn yellow, which then results in defoliation. Furthermore, it can create the worst case of sunscald.

– Verticillium Wilt

Now we will go back to Fungus related diseases. Verticillium Wilt disease happens because of Verticillium Dahliae. This disease is very dangerous because it can also destroy other plants and trees surrounding the tomato patch.

The disease first infects older and lower-lying leaves. Just like with other diseases, as it becomes more contaminated, it will develop brown patches. The last step is the dying leaf. The same thing happens to stems, and it is not identified early, it might destroy not only the tomato patch, but also the whole garden. 

– Spider Mites

As mentioned above, another common cause of tomato leaves turning brown is pests/insects. The most common insects are spider mites. If you notice brown specks on the leaves with thin webbing, it means that this is your issue.

They attack the tomato leaves in groups and nestle on the undersides of leaves. These pests love to suck the sap from the leaves, which can cause strange brown spots. The result is a dying leaf. Dying leaves in turn can result in dying plants. 

How to Solve Tomato Plants Brown Leaves Issues?

To solve tomato plants’ brown leaves issues, you can try watering the plant more often and fixing the watering schedule, preventing the spread of diseases, and creating a good environment. If the cause is due to disease, the only solution would be to destroy the plant as soon as possible.

It is important to inspect your tomatoes frequently. This way, it can prevent disease spreading. It can also save time and energy, as well as the garden in some cases. Inspection will help you to find the disease before it can spread and destroy the plant. Introduce good parasites to your garden. This way, you can prevent insects from entering your garden. 

– Correct Watering Method and Frequency

As stated before, tomatoes love water. Hence, it is crucial to water them frequently, deeply, and slowly. It is specifically important during its early stages. The gardener should establish a certain routine and pay attention to its consciousness. This routine helps to grow healthy and strong. When it becomes stronger, the gardener should not break the routine. 

Tomato Leaves Turning Brown Cure

Tomato plant roots are deep into the soil. Sometimes they can go as deep as five deep. Not enough water might not reach five feet under the root. Therefore, the best way to water tomatoes is to focus on the soil around the base of the plant. It is also crucial to avoid watering overhead as this can lead to the spreading of diseases if the tomatoes have any. 

– Prevent the Spreading of Diseases

If your cause is a disease, most of the time, it is impossible to cure or save the plant. We will go one by one to see if we can save the plant from diseases. 

  • Early Blight- If caught in time, you can cure the tomatoes. Inspect the tomatoes frequently. If the symptoms mentioned above are there, remove the foliage. Apply copper-based fungicide. It can kill any lingering infection.
  • Late Blight- Sadly, this is incurable. If the signs are there, destroy the plant immediately to prevent the disease from taking over. It is a crucial factor to have correct gardening hygiene and watering method crop rotation. 
  • Cranker- Just like the previous disease, this is incurable. Remove infected leaves and take care of the rest. The same rules for prevention as the last two apply here as well. 
  • Bacterial leaf- Again, if the leaf is infected, it is incurable. Get rid of infected stock to save a healthy one. To prevent the disease, follow the steps outlined above. Check surrounding stock and plants for signs of disease and replant healthy stock. 
  • Verticillium Wilt- This is also incurable. If the plant is infected, uproot it and destroy it. For prevention, follow the same rules as the last one and plant varieties of tomatoes that are resistant to the disease. 

– Create an Appropriate Environment

These pests thrive in hot and dry climates, so with the help of watering, you can keep the environment humid and spider mite-free. To keep them away, you can also introduce good parasitic pests to your garden. 

Another prevention method is to use spray against the pests. If it does not work, uproot and destroy the plant and replant a new one. Keeping up with the hygiene rules can also help prevent their appearance

Tomato Leaves Turning Brown Thoughts


After reading the article, it is easier to understand why your tomato plant leaves turn brown. You have even learned about ways to solve your issue, so let us sum up what we have learned today. 

  • Tomato leaves turn brown due to different reasons. The most common of them being wrong watering and hygiene regulation.
  • Other common causes include disease by fungi or bacteria. The most common among them are late and early blight (fungal) and leaf spot (bacterial).
  • Pests and insects can also cause the leaf to turn yellow. A common pest among them is the Spider mite pest. If this is the issue, it is incurable.
  • The solutions depend on the issue. If it is simple watering, then the solution is good garden hygiene and correct watering. If the problem is a disease, the best solution is to uproot the plant and replant it.
  • We have also covered some of the prevention methods. It includes using sprays (for the pests), planting a variety of tomatoes that are disease-resilient, and checking tomatoes frequently.

You can inspect your tomato plant to find out the cause and fix it on your own. Following the advice from above, you can enjoy your gardening and eat the tomatoes that you have grown on your own.

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