Septoria Leaf white spots on tomato leaf

White Spots on Tomato Leaves: Causes and Solutions

You’re strolling through your flourishing garden, basking in the pride and joy that your juicy, ripe tomatoes bring. But as you lean in closer, you notice white spots on your prized tomato leaves.

White spots on tomato leaves can be caused by Septoria Leaf Spot, Powdery Mildew, and Sunscald.

The presence of these white spots is more than just an eyesore. They can escalate into a serious threat that can seriously affect the health of your plants if not dealt with promptly. 

Ignoring these warning signs could lead to devastating losses in your garden, transforming your potential bounty into a barren wasteland.

Luckily, with the right information, detection strategies, and preventative measures, you can reclaim the health of your tomato plants and enjoy the abundant harvest you’ve worked so hard for. So, let’s dive in and get to the root of the problem!

Identifying White Spots on Tomato Leaves

As a gardener, you might have encountered white spots on your tomato leaves. These spots can be a sign of various issues, and it is essential to identify the cause to properly treat and prevent further damage to your plants. Let’s take a look at the three most common reasons for white spots on tomato leaves: Septoria Leaf Spot, Powdery Mildew, and Sunscald.

Septoria Leaf white spots on tomato leaf

Septoria Leaf Spot

Septoria Leaf Spot is a fungal disease that causes the appearance of small, circular white spots on your tomato leaves. These spots may have a dark brown or black center and are often surrounded by a yellow halo. As the disease progresses, the spots can merge, causing extensive damage to the leaves.

To manage Septoria Leaf Spot, you should regularly inspect your tomato plants for symptoms and consider using a fungicide treatment at the first sign of infection. Additionally, you can minimize the risk of infection by selecting disease-resistant tomato varieties, rotating your crops, and maintaining proper air circulation and moisture levels among your plants.

white spots on tomato leaves caused by powdery mildew

Powdery Mildew

Powdery Mildew is another fungal disease that affects tomato leaves. It appears as white, powdery spots on the leaves’ surface, often accompanied by yellow or light green discoloration. This fungus thrives in hot and humid conditions and can spread rapidly, causing significant damage to your plants.

When dealing with Powdery Mildew, sulfur dust, fungicides, and bio fungicides can help treat the affected leaves. To prevent future outbreaks, prune your tomato plants to ensure proper air circulation, avoid excessive watering, and use horticultural oil to control the spread of the fungus.


While not a disease, Sunscald can also cause white spots on tomato leaves. This issue occurs when your tomato plants receive an excess of sunlight or experience sudden changes in sunlight exposure. The result is white, bleached spots on the leaves, which can later turn brown and dry.

The most common reason for Sunscald is not properly hardening off your plants.  To help avoid Sunscald, you should provide your tomato plants with partial shade during the hottest part of the day. Gradually adjust any newly transplanted or unshaded plants to increased sunlight exposure to avoid leaf damage. Furthermore, ensure adequate watering and mulching to help your plants maintain proper moisture levels and recover from Sunscald.

Causes and Contributing Factors

There are several factors that can lead to white spots on tomato leaves. In this section, we’ll discuss the most common: fungal infections, environmental factors, and pest infestations.

Fungal Infections

One primary cause of white spots on tomato leaves is fungal diseases like powdery mildew. This infection is caused by several types of fungi and often appears as a white powdery residue on the leaves. Fungi are usually carried by air currents and insects, like aphids, making it challenging to avoid this problem. So, make sure to be observant and take preventative measures to protect your tomatoes from fungal diseases.

Environmental Factors

Environmental factors like humidity and temperature can also contribute to white spots on tomato leaves. High humidity levels can create a favorable environment for disease growth, while fluctuating temperatures may stress the plants, leading to sunburn, which can cause white spots on the leaves. To prevent these issues, ensure your tomato plants receive the appropriate amount of sunlight, maintain a suitable temperature, and monitor the humidity levels in your garden.

Aphids on tomato leaves

Pest Infestations

Lastly, pest infestations can be a significant cause of white spots on tomato leaves. Some insects, like aphids, can transmit diseases to the plants while feeding, resulting in the appearance of white spots. Additionally, some pests may cause direct damage to the leaves, leading to spotting. To combat these infestations, be sure to regularly check your tomato plants for any signs of pests and take appropriate action if you find any.

It’s essential to keep an eye on your tomato plants and react quickly to any changes in their appearance. By understanding the causes and contributing factors behind white spots on tomato leaves, you’ll be better equipped to maintain a healthy and bountiful garden.

Prevention and Treatment

White spots on tomato leaves can often be prevented, but if you’re reading this, you probably already have them, so let’s take a look at how to not only treat them but prevent them from happening in the future.  These cultural practices, fungicides and pesticides, and resistant varieties will ensure your tomatoes remain healthy and vibrant.

Cultural Practices

To prevent white spots on your tomato leaves, follow these simple yet effective steps:

  • Maintain good air circulation by spacing your plants properly and regularly pruning your plants.
  • Water your plants at the base, preferably in the mornings, to avoid wet foliage that can cause fungal growth.
  • Apply a layer of mulch around your plants to help regulate soil moisture and temperature.
  • Sanitize your gardening tools and remove any diseased plant debris from your garden area.
  • Avoid excessive use of nitrogen-rich fertilizers, as this can promote rapid growth and increase susceptibility to diseases.

Fungicides and Pesticides

Using fungicides and pesticides can help control white spots on tomato leaves. Here are a few options:

  • Apply neem oil to your plants as a natural, organic option to combat fungal infections.
  • Use copper fungicides for added protection against disease in your garden.
  • Consider a milk spray, which has been shown to be effective against powdery mildew, a common cause of white spots on tomato leaves.
  • Follow the label instructions carefully, and reapply your chosen treatment weekly until the issue is resolved.

Resistant Varieties

If you have a history of white spots on tomato leaves in your garden, you might want to consider planting resistant varieties:

  • Look for tomato varieties that are labeled as resistant to various diseases, including early blight, late blight, and powdery mildew.
  • Consult your local plant nursery or cooperative extension service for advice on the best-suited resistant varieties for your region.
  • Keep in mind that, even with resistant tomato varieties, it’s essential to maintain healthy cultural practices and preventative measures.

By following these preventative measures and treatment options, you can keep your tomato plants healthy and free of white spots on their leaves. Remember to monitor your plants regularly and take action as soon as you notice any signs of disease or pest infestation.

Managing Garden Conditions

The best to deal with white spots on tomato leaves is to not get them in the first place, and the best way to do that is through good garden management.  

Spacing and Pruning

Proper spacing and pruning can help prevent white spots on your tomato leaves. Ensure that your tomato plants have enough space for air circulation and light penetration. Typically, a distance of 18 to 24 inches between plants is ideal, depending on the variety. Wider spacing allows for better air circulation, reducing the chance of fungal infections.

Prune your tomato plants to maintain a good balance between growth and airflow. Remove any dead or damaged leaves, as well as lower leaves that are too close to the soil. This will help prevent the spread of diseases like powdery mildew and improve overall plant health.

Soil and Fertilization

The quality of the soil impacts your tomato plants’ overall health. Use a well-draining soil mix with organic matter to improve the soil structure and provide essential nutrients. Adding compost or well-rotted manure can also enrich the soil and promote healthy plant growth.

When it comes to fertilization, avoid overdoing it. Excessive nitrogen can cause your tomato plants to produce lush foliage, making them more susceptible to diseases like white spots. Stick to a balanced fertilizer, and apply according to the package instructions.

Light and Temperature

Tomato plants thrive in full sun and require at least 6 to 8 hours of direct sunlight per day for optimal growth. However, during periods of intense heat or prolonged high temperatures, it’s essential to provide some shade to prevent sun scalding, which can result in white spots on the leaves.

To help regulate temperature and protect your tomato plants from extreme fluctuations, consider using shade cloth, row covers, or planting in an area with partial shade from nearby trees or structures. It’s also essential to monitor the weather and adjust your care practices accordingly to ensure a healthy growing season for your tomatoes.

Common Tomato Diseases and Pests

Sometimes, white spots can’t be avoided and it’s important to know exactly what you’re dealing with so you can formulate the best treatment plan. 

tomato plant diseased with late blight

Late Blight

Late blight is a serious disease that affects tomato plants, caused by the fungus-like organism Phytophthora infestans. It begins as small, white spots on the leaves, which quickly turn into brown or black lesions. If left untreated, it can spread and eventually destroy your entire crop. To prevent late blight, it’s crucial to provide proper air circulation, avoid overhead watering, and remove any affected plant parts immediately. When transplanting your tomato seedlings, ensure they are well-spaced apart, and try to select disease-resistant varieties.

Alternaria Leaf Spot

Alternaria leaf spot is a common fungal disease that affects tomato plants. The first signs are small, dark brown spots on the leaves. These spots can grow larger and merge, causing the leaves to yellow and die. To manage this disease, make sure to water your tomato plants at the base to keep the foliage dry, remove and dispose of infected leaves, and provide adequate spacing between your plants. Treating the plants with a fungicide can also be helpful in controlling Alternaria leaf spot.

Tomato Aphids

Tomato aphids are small insects that feed on the sap of tomato plants. They can cause damage by introducing plant diseases and causing the leaves to curl, turn yellow, or develop black spots. To keep aphids at bay, regularly inspect the undersides of tomato leaves for these tiny pests and remove them with a strong stream of water. Additionally, you can introduce beneficial insects, such as ladybugs, to your garden, which will help control aphid populations. Limit the use of broad-spectrum insecticides that can also kill these helpful insects.

By keeping an eye out for these tomato diseases and pests, you’ll be able to take appropriate measures to protect your plants and their yields. Proper care and management can make a significant difference in maintaining the health of your tomato plants, ensuring delicious-tasting tomatoes for you to enjoy.

Frequently Asked Questions

How do you treat white spots on tomato leaves?

To treat white spots on tomato leaves, first, identify the cause. If it’s a fungal infection like powdery mildew, you can apply fungicide or a homemade solution like diluted milk or baking soda spray. Regular pruning, adequate use of fertilizers, and proper watering can also help keep your plants healthy and prevent the spread of diseases.

What causes white spots on my tomato leaves?

There are several potential causes for white spots on tomato leaves, such as powdery mildew, nutrient deficiencies, sun scalding, or even certain pests. Identifying the exact cause is important to provide the right treatment and keep your plants healthy.

Are white spots on leaves always mildew?

No, white spots on leaves are not always mildew. They can also be symptoms of nutrient deficiencies, sun scalding, or the presence of pests. Always inspect the affected leaves and look for the presence of powdery residue or tiny insects before concluding the cause.

Why are tomato plant leaves turning white and curling?

If your tomato plant leaves are turning white and curling, it could be due to a lack of nutrients, such as nitrogen or phosphorus. Proper fertilization, scheduled watering, and good soil drainage will help address nutrient deficiencies and prevent leaf problems.

How does sunscald affect tomato leaves?

Sunscald typically occurs on tomato leaves during hot and sunny days when plants receive intense sunlight. It can cause the leaves to develop white spots or patches, which can further progress to sunburned, brown, and dead tissue. To prevent sunscald, provide shade to your plants and ensure they are well-watered to maintain turgor pressure in the leaves.

What are common white bugs found on tomato leaves?

One of the common white bugs found on tomato leaves is aphids. These tiny insects can cause plant damage by sucking sap from the leaves, leading to white spots, yellowing, and leaf curl. Combat aphids by introducing natural predators like ladybugs or using insecticidal soaps or neem oil sprays for more severe infestations.

Final Thoughts

From nutrient deficiencies to pathogenic invasions, the causes can vary, but one thing remains the same: swift, informed action is key to preserving your bountiful tomato harvest.

We’ve explored numerous strategies to combat this issue, from adjusting your watering routine to using eco-friendly fungicides and even incorporating crop rotation. By taking these precautionary and corrective steps, you can effectively manage and even prevent the appearance of white spots on your tomato leaves.

So, the next time you’re out in your garden, and you notice the first signs of white spots on your leaves, don’t panic. You are now equipped with the knowledge and tools to effectively handle this situation. Start applying these solutions, and remember, consistency is crucial. The health of your tomato plants – and the promise of a rich, rewarding harvest – lies in your hands.

Until next time, happy gardening!