White Spots on Tomato Leaves: What They Mean and How To Prevent

Are you tomato growers and you are seeing white spots on the leaves? Healthy tomato leaves are Pale Green to Dark Green and look glossy. But what if your tomato leaves look yellow, brown or purple? I have often seen white spots on my tomato plant leaves. This is the symptom which alarms that tomato leaves are not healthy and they need immediate treatment. 

So, what causes white spots on tomato leaves? In short, the white spots on tomato leaves or stems are due to fungal diseases; if you don’t prevent this, your tomato leaves will turn yellow and then brown. Powdery mildew, Sun Scalding and Late Blight are the common causes of white spots in tomatoes.

Proper care and ideal growing conditions never let this situation arise. However, you already have infected plants, do not worry; I have explained certain ways to deal with it. 

Always choose a variety of tomatoes which are less prone to get infected, prune the infected leaves, maintain proper spacing while planting the tomatoes etc. 

In this article, I briefly discuss the causes and effects of white spots on tomato plants. If you want to prevent white spots on tomato plants, keep reading!

Why Do You See White Spots on Your Tomato Plants?

Mainly there are three main reasons for white spots on the tomato plants. You must know what causes these white spots to prevent this from happening again.

Powdery Mildew

Powdery mildew is an unavoidable tomato plant disease commonly seen in tomato plant leaves, and different fungi are responsible for the cause of the disease. 

Moist and dark places attract these fungi. When it is highly humid, with insufficient sunlight exposure and bad air flow facility, these fungi are attracted towards the tomato plants, resulting in Powdery Mildew fungal disease. 

It can be identified in powdery white color form and initially catches the underneath leaves of tomato plants which is very hard to trace initially. New leaves are the first to get affected by the disease, and it gradually spreads to buds and fruits. Newly fertilized plants are more prone to get infected due to the disease.

Though the fungus won’t destroy the plant, it harshly impacts fruit production, and the taste of tomato is also impacted because of insufficient photosynthesis. It also weakens the plants, and plants are more prone to other diseases. Gradually the leaves turn yellow as the plant starts losing its cells. 

It is important to keep an eye on the plant to track if you own tomato plants are going through any disease. Take immediate action if you discover the symptoms of Powdery Mildew, as early diagnosis can easily save your plant.  
You can also treat Powdery Mildew by using Neem oil, as it acts like an organic pesticide without any side effects. 

Commercial and Bio Fungicides can also be safely used to treat your plant. 

Pruning of affected leaves is also a good option. Repeat the process weekly until your plant is free from such disease. 

How To Prevent Powdery Mildew?

You can take various measures to prevent Powdery Mildew easily and rapidly. Please check out the points below.

1. Proper spacing: Powdery Mildew happens because of bad airflow facility. Try maintaining 18 – 24 inches spacing for adequate air circulation through the tomato plant leaves. Dense plantations of tomato plants encourage powdery mildew. (Check can you plant two tomato plants together)
2. Exposure to sunlight: Powdery Mildew happens when the plants do not get enough sunlight and face darkness most. Ensure your plants receive 6-8 hours of direct sunlight daily to avoid the disease. 
3. Pruning: Pruning is one of the best options to decrease the risk of Powdery Mildew, as pruning helps to improve air circulation. But never forget that over-pruning can easily destroy the plant. Only when the leaves are overgrown pruning methods are applied. Always ensure to sanitize your pruning tool before and after use. 
4. Choosing the right species of tomatoes: Always opt for the varieties which are more resistant to Powdery Mildew. I prefer planting ‘Geronimo’, ‘Imperial 643’, ‘Massada’ and ‘Panzer’ as they are more resistant to powdery mildew disease and the right variety. 
5. Avoid using Powdery Mildew infected plant compost. It may leave a negative impact on the plants, dispose of them.
6. Use of fertilizer in the right amount: Keep the habit of using the fertilizer in the right amount, enhancing the health and growth of your tomato plant. Avoid over-fertilizing your plant, as it increases the number of new leaves, which are more prone to get infected due to the disease.
7. Prevention is better than cure. So keep a habit of using sulfur dust or bio fungicides every week.

Sun Scalding (Insufficient or Too Much Exposure To Sunlight)

Sunlight is important for food and the growth of plants, but anything more than a limit is a matter of concern. 

When tomato plants get more than the ideal amount of sunlight, they have to go through sun scald, which turns their leaf white spotted and damaged. This can happen when you expose them directly to the sun and the outside world when transplanting your greenhouse plant and indoor plants. So avoid rushing the hardening of your tomato plants too early. 

The affected tomato plants leaves turn yellow, dry out and again brown and shade from the plants, resulting in damaged and unhealthy tomato plants. 

How To Prevent Sun Scalding?

1. While hardening off your tomato plants, arrange a comfortable environment for them for at least 7-10 days.
   • Keep the plant outside in the shade for only a few hours on the first day. Then expose the plants to direct sunlight slowly and gradually.
   • On the 10th day, keep the plant outside at night when the temperature is more than about 50F.
   • If your plant can survive in such a situation, it is ready for an outside environment.
   • If the condition is not yet up to the mark, stretch the process for a few more days.  
2. If you have already exposed your plant to the sun, arrange for shade with the help of clothes to prevent them from sun scalding. Over time, you can increase their exposure to sunlight. 

Late Blight

Late Blight is a disease which may destroy your tomato plant’s leaf. White fungal spots are visible on the infected leaves. It also spreads to the branches of tomato plants, and plants produce very bad quality, brown spotted tomatoes. 

The disease is mainly spread by phytophthora infestans, which spreads all over the plant and is enough to kill the plants in 2-3 days. It is better not to use them in compost; rather, disposing off is the only best option as it can ruin your garden. 

You need to actively take care of your plant, especially in summer, autumn and wet weather, as Late Blight only spreads more during these times. 

Infected leaves will have pale green spots that become brown and sometimes black. Brown spots with white fungus develop in Green tomatoes too. 

How To Prevent Late Blight?

You can take care of late Blight in the following ways:

• Applying copper fungicide or bio fungicide every week helps reduce Late Blight, and your plant can eliminate the disease.
• Potato and tomato plants come from the same nightshade family. They require the same type of soil and nutrients to grow and are susceptible to the same kind of viruses and diseases. Planting them in the same place makes the plants compete for nutrients, leaving both plants unhealthy and getting Late Blight. So I never chose to grow both plants in the same place.
• As Late Blight is a very dangerous disease which destroys plants, always follow USA Blight to check the outbreak of the disease in the whole country. In this way, you would easily identify if the disease is spread in your area and take preventive measures to save the life of your tomato plants. 

Other Reasons For White Spots on Tomato Plants?

Apart from Powdery mildew, Sun Scalding and Late Blight, I have found some more reasons that can cause this problem.

Poor Air Circulation

Poor Air circulation is one of the reasons that can bring white spots or even powdery mildew to your tomato leaves. 

You can prevent this by pruning your tomato plant and encouraging growth. Pruning improves air circulation; therefore, you only need to remove the leaves with white specks. 

Tomato Psyllids

Tomato Psyllids are whitish or yellowish plant lice which are too small to be identified. They are just 0.12 inches or 3 MM.

They damage the plant by injecting a toxin while feeding on the leaves, which results in leaf curling and makes the plant inefficient in producing fruits and produces white spots on the plants.

Whiteflies

We are often tricked into recognizing the presence of whiteflies as they look like white spots when present in large numbers on the leaves.

They live underneath the leaves, which leads to the curling of leaves and later, the leaves are totally destroyed.

Spider Mites

According to Kansas State University Horticulturist, spider Mites create more problems for tomato plants. They create a white web which looks like white fungus.

“The tiny insects feed on the underside of the plant leaves and suck the juices out of the plant, causing the leaves to turn yellow and ultimately die,” said Rebecca McMahon, Kansas State University Research and Extension horticulture agent in Sedgwick County, Kan. 

How Do You Treat White Spots on Tomato Plants?

It is tough but not impossible to get rid of white spots on tomato plants. Be proactive in taking care of your tomato plants, so they never catch any disease. 

But if they are already infected, please follow the steps below, as they were helpful and successful for my infected tomato plants. I am sure it would also benefit you. 

Remove the damaged leaves:

It is very hard to get back the infected leaves of tomato plants. So the best option is to remove the damaged leaves by pruning.

I use this Pruning Garden Clipper, which gives the best result. Please keep the following points noted for removing the damaged leaves:

• Avoid clipping the less damaged leaves.
• Thoroughly clean your pruning clipper before using it.
• Don’t forget to disinfect your clipper with alcohol or bleach each time after completing the pruning process.
• Dispose of the plant’s waste and do not use it as compost as they are already infected and cause health issues and fungal spores in your new or existing tomato plants if used as compost.

Spritz your tomato plants with Neem Oil

You can treat white spots on tomato plants by spraying Neem Oil on the plant. Neem has antiseptic properties, which are enough to kill insects, germs and pests and hence used to treat white spots on tomato plants too. 

Certain points to be remembered before its spritz on your infected tomato plants:

• Strictly avoid using neem oil during day time and exposure to sunlight. There are high chances of getting other leaves damaged.
• You can only use it in the evening. Spread the oil all over the tomato plant and beneath the leaves to get rid of the white spots issue.
• In the absence of ready-to-use neem oil, you can mix neem leaf powder with water and apply it to the plant. This also helps recover the tomato plant spot issues and acts as an organic pest controller. 

Monitor Your Tomato Plant

After the treatment, monitoring your plant’s health is very important, as it helps us understand whether the treatment was effective or not.

Due to Neem’s antiseptic properties, it acts as an organic pesticide and fungicide. It helps the tomato plant to get rid of spots soon. Regularly monitor the plant to see any increase in white spots and insects.

If you notice any growth in fungus and insects, repeat the process after a week and continue this process until the issue gets resolved. You could get your precious tomato plants back in healthy and disease-free condition. 

Summary

Though white spot on tomato plants is a serious issue, if the proper measures are taken, you can get rid of the disease. Try to identify the problem at the initial stage, and it will be easy for you to save your plant from diseases.

If you always look closely and keep an eye on your tomato plants, you will never face the problem of disease, and at the same time, plants reward you with many quality fruits. 

Frequently Asked Questions about White spots on tomato leaves

How to treat light spots on tomato leaves?

You can follow the below steps to treat light spots on tomato leaves. (1)

1. Pluck the leaves that has spots and put them into compost pile.
2. Remove all the leaves that has catched disease.
3. It is recommended not to remove more than one third of the plant leaves.
4. Always try to keep the leaves dry to prevent spreading of the disease.

Do white spots on Tomato leaves mean the plant will die?

When you see white spots on your tomato plant leaves, it doesn’t mean that the plant will die. Mostly the spots apeear due to sun scalding, when they are exposed to intense sunlight, they begin to turn white.

Are white-spotted tomato safe to consume?

The white spot on your tomato fruit is caused due to stink bugs, the fruit remains safe to consume. But, when you pick these fruits, they spoil fasted as compared to fruits with no spots.

Can I eat cherry tomatoes with white spots?

When you remove the skin, you see a exposed a spongy fibrous tissue that is white (sometimes yellow). According to researchers at Auburn University, it is possible to cut out any affected areas and still use the rest of the fruit for fresh consumption or canning.”