Skip to Content

3 Main Reasons for Spots on Tomato Leaves

3 Main Reasons for Spots on Tomato Leaves

Tomatoes are a highly versatile fruit, which makes them a favorite plant amongst gardeners across the country.

These plants, which are often harvested in July and August, thrive in US zones 5-8 but can be planted and grown just about anywhere.

Although these fragrant and delicious fruits are easy to grow, they do come with their own unique set of potential problems (such as spotted leaves).

If you’re wondering what the reasons for spots on tomato leaves are, you’ve come to the right place.


Reasons for Spots on Tomato Leaves

Spots on tomato leaves are usually caused by Septoria leaf spot, bacterial spot, and early blight. There are a few different treatment options, but it is important to start the treatment early to prevent the disease from spreading to other plants or killing the infected plant.


Causes and Treatments for Spotty Tomato Leaves

Since the bacteria that plague tomatoes live in the soil, the earliest signs of disease will be found on the tomato leaves that are closest to the ground.

You will want to frequently inspect these leaves in order to catch the potential disease early on and treat the plant before the disease has the chance to spread. The start of the disease will present as small dots that are brown or black in color.

Prevention is best when it comes to plant ailments that create spots on your tomato leaves.

Since your plant can survive and produce fruit with two-thirds of its leaves intact, you might consider removing the first one-third of the leaves closest to the soil.

This will make it more difficult for the disease to take hold of the leaves, allowing your plant to guard itself against pathogens.

Another prevention technique is to keep your tomato leaves dry, as this will make it harder for disease to spread or take hold in the first place.

As stated above, many gardeners remove the bottom one-third of leaves not only to prevent disease but to also help the plant expose its leaves to sunlight. This helps the leaves stay dry and prevent the spread of disease.

If you notice that your tomato leaves start developing spots, you will want to remove them. You can safely remove up to one-third of tomato leaves but if the disease has impacted more than this amount, you will need to get rid of the plant entirely.

Tomato plants need at least two-thirds of their leaves in order to produce fruit. In addition to this, once the disease has taken over this much of your plant, you now run the risk of it spreading to surrounding plants and multiplying at fast rates.

Mulching your garden is another way to help reduce infection risk. You can use fabric, straw, or other storebought mulch to help guard the leaves against disease.

If you’ve heard about mulching your garden with grass clippings, you should know that this is not a safe way to mulch (especially with tomato plants).

Many lawns are treated with chemicals such as herbicides, which are toxic to the tomato plant (and to those who are consuming the fruit).

It is inadvisable to use fungicide on tomato plants unless all other methods of prevention and treatment have failed.

If you must use a fungicide, be sure to follow the manufacturers’ guidelines closely to avoid any potential complications that could arise.

You should also speak with the employees at your home garden store for any recommendations they have, should your plants require the use of a fungicide to treat disease.


Frequently Asked Questions About Spots on Tomato Leaves


What are some ways I can prevent diseases from causing spots on my tomato plants?

One of the most important prevention techniques is to keep the tomato leaves dry and to avoid watering the leaves (always aim for the soil). Avoid handling your tomato plants when they are wet, as the disease can spread via your hands or garden tools (and bacteria travels best in water). Finally, you can use a trellis on your tomato plants or stake them to help with airflow, which helps your tomatoes stay dry and reduce the risk of disease.


What causes the spots on my tomato leaves?

Spots on tomato leaves are usually caused by bacteria which create diseases in the tomato plant. Common diseases that cause this are bacterial spot, early blight, and Septoria leaf spot. Always use prevention techniques in order to prevent these diseases from taking hold and spreading throughout your crop.


Should I use fungicide on my tomato plants if they are showing signs of disease?

You should not use fungicide on your tomato plants unless other methods of prevention and treatment have not worked. If you opt using a fungicide, follow the instructions to the dot. Prior to consumption, you will want to wash your tomato plants well to remove any remaining fungicide.


Ridding Your Tomatoes of Spotty Leaves

Almost every tomato garden will come across the issue of spotty leaves at some point during its lifespan.

Remember that prevention is key, and be sure to utilize the above prevention methods to help avoid the spread of disease in your plants.

If the disease has already occurred, don’t panic and begin treating it as soon as possible. I hope this has helped you get to the bottom of your spotted tomato leaves and that you have a healthy and bountiful crop in the coming season.

7 Reasons Why Your Amaryllis is not Growing
Why Are My Carrots Not Growing? Thats Why!