3 Most Common Reasons For White Spots On Tomato Leaves (And If It Can Be Fixed)

While growing tomatoes isn’t very hard on its own, making them the best they can be in terms of quality is much harder, especially if you don’t know what certain physical signs mean such as white spots that will occasionally pop up on the leaves of a growing tomato. 

3 Most Common Reasons For White Spots On Tomato Leaves (And If It Can Be Fixed)

While this is actually a very common occurrence, it also needs to be dealt with as soon as possible since it signifies a much bigger issue that can affect the plant’s overall well-being along with its growth and development. 

With that being said, if you do happen to find a few small and peculiar-looking white spots propping up on the leaves of your tomatoes, we’re here to tell you why, along with how deadly they actually are and how to fix them (Also check out Reasons Your Tomato Leaves Are Turning Purple). 

Why Do White Spots Appear On Tomato Leaves?

1. Sunscald

White spots can begin to appear on tomato leaves when it is suffering from sunscald, which is when the tomato is exposed to too much sun and is having a hard time trying to adjust to its environment. 

The heavy exposure to the sun causes the plant’s foliage to turn white with the leaves then curling up and eventually breaking off.

This takes the form of small and rough white blisters that run across the leaves of the tomato, and while they are commonly found around the edges of the leaf, they will also go through the middle in some cases. 

While the sun is the main problem, heavy wind will also exacerbate the conditions, blowing more hot air toward the plant and damaging the plant’s foliage, leading to these small and annoying spots.

These spots initially take on a white appearance, but they eventually become a clear white when the condition is left untreated for a prolonged period.

2. Late Blight

Late blight is a fungal disease that is highly contagious and can kill a plant in just a few days.

The spots that appear are usually a lot larger than those that appear due to sunscald, and they can also be brown instead of white in many instances.

The fungus that causes late blight is called Phytophthora Infestans, and while it can be hard to prevent, the spots of the infection will start to appear immediately.

If you suspect that your tomato is suffering from late blight, it’s important to destroy the plant and don’t add it to your compost, otherwise, you put it at risk of infecting your entire garden. 

3. Powdery Mildew

Unfortunately, powdery mildew is a very common disease that afflicts many tomatoes, making it a real nuisance to deal with for many gardeners.

The reason it can be so difficult to detect is because it is caused by aphid insects and air currents, meaning there aren’t too many reliable methods of protecting against it. 

However, with that being said, powdery mildew most commonly occurs in dry and hot climates, and similar to sunscald, it can be much more prone to catching the disease when left out in the sun for too long. 

The white and gray dust that appears as a result of powdery mildew takes the form of spots which will first begin appearing on the underside of the leaves before then growing to the top, which is why it’s always vital to check every inch of your tomato leaves when exposing them to sunlight for a few hours at a time. 

Unlike late blight which is deadly to the tomato, powdery mildew is not deadly and it is very unlikely it will kill the plant, though it can reduce the yields and overall quality of the crop by ruining the taste of the tomato. 

Can You Cure A Tomato Once It Has White Spots?

While a tomato can become cured if it has contracted powdery mildew, sunscald cannot be cured completely and can only be slowed down, while powdery mildew acts so fast that it is virtually impossible to cure. 

Because of this, it’s important to detect the type of spots that appear, specifically how big they are, and their color, to determine what is affecting the tomato and if it should be destroyed and thrown away to prevent the disease from spreading. 

How To Cure Powdery Mildew

As mentioned previously, powdery mildew is the only white-spot infection that can be completely cured, and the good news is that there is a high chance your tomato will be back to full health and not put in any danger of further damage, as long as you take the necessary steps before it’s too late. 

Start by picking up a commercial fungicide. These are specially designed to treat plant infections without using any harmful chemicals which could be dangerous to the plant’s well-being.

You will then need to cut away any leaves, or disease spots on the tomato before then spraying the rest of the plant every few days, at least twice a week. 

The fungicide will ensure that the infection has not continued spreading in the tomato so that it can’t re-emerge, which is always a nightmare to deal with for gardeners. 

3 Most Common Reasons For White Spots On Tomato Leaves (And If It Can Be Fixed) (1)

How To Slow Down Sunscald

Once a tomato has become impacted by sunscald, the effects are irreversible on the leaves that it has infected, however, you can help to slow its spread to protect the plant from further damage so that it can still be of decent quality once it’s fully grown and ready to harvest. 

Simply leave exposed fruit around the vines and then cover it with a shade cloth or lightweight screen so the leaves aren’t too overexposed to the sun. 

Ways To Prevent White Spots From Appearing On Tomato Leaves

There are a few ways you can prevent any of these three infections from affecting your tomatoes.

Here are a few protective measures that you should always keep in mind:

  • Only leave tomatoes in direct sunlight for six to eight hours each day. 
  • Make use of shade cloths as an easy way to protect against sun exposure. 
  • Regularly apply bio-fungicide or copper fungicide at least once a week.
  • Check USA Blight to see if there are any late blight infections near your growing area.
  • Make sure to fertilize your tomatoes regularly to help protect them against diseases.
  • Avoid getting the leaves wet when watering since this can attract fungus and disease. 
  • Try to space the tomatoes out 18 inches apart so that they have good airflow. 
  • Avoid planting tomatoes near potatoes since they will both compete for the same nutrients which can lead to disease and infections. 


There are multiple reasons why small white spots might be appearing on your tomato leaves, however, no matter what the tomato has been infected by, it’s always important to cut off the leaves to avoid it spreading, and take the necessary steps to help save the planet and protect it if it has been struck by sunscald or powdery mildew. 

If you suspect the plant has picked up a case of late blight however, it’s worth throwing it away completely since it is very contagious and deadly, so you’ll want it nowhere near your compost. 

Amelia Haslehurt
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