What Causes White Spots On Tomatoes?

You spend hours in the garden ensuring your plants stay healthy and happy so you can harvest a bunch of tasty tomatoes. But wait, what are the spots on my tomatoes? Nothing is worse than pests and diseases reducing your yield and trying to identify how to get rid of the problem. This guide will give you a good idea about what causes white spots on tomatoes.

Most Common Issues

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Small white spots on tomatoes can be caused by a few different pests or diseases. The good news is that most of them don’t mean you have to throw away all the tomatoes. The bad news is that all of these problems can look similar and can be hard to solve.

1. Stink Bugs

White spots on green tomatoes can be caused by stink bugs or other insects feeding on the inside of the tomato. They insert their needle-like mouths to be able to suck out the juices. This leaves behind a yellowish-white spot on the tomato skin and the inside of the tomato to the depth of their insertion. This is the most common cause of white spots on tomatoes.

The Brown Marmorated Stink bug is a particularly tough pest to deal with, which you can learn more about here.

2. Nutrient Deficiency

Nutrient deficiencies can cause a multitude of problems, including blossom end rot. This problem is the easiest one to solve, however. Simply applying a balanced organic fertilizer to your tomatoes regularly will reduce all risk for nutrient deficiencies.

3. Sunscald

What does Sunscald look like on tomatoes? It causes a discolored spot on the tomato skin when too much sun exposure has reached a ripening tomato. Too much pruning is usually the culprit.

How do you treat Sunscald on tomatoes? Once it happens, the affected tomatoes can’t be cured, but you can simply cut out the bad spot before eating or preserving. You can solve this issue by pruning less and providing shade cloth if necessary.

4. Cotton Spot

Hot and humid conditions that are persistent through the beginning of tomato development can cause Cotton Spot. Ensuring that your soil drains well and you have ample amounts of calcium in your soil by adding amendments like bone meal or eggshells will help reduce the risk for this disease.

5. Bacterial Canker

This disease looks a lot like the damage caused by stink bugs feeding on your tomatoes. If you pull out a magnifying glass and look at the spots, Bacterial Canker will have a dark perimeter around the spot. This disease is typically caused by exposing your tomatoes to the bacteria with dirty garden tools that haven’t been sterilized.

Treatments

If the problem is pests, be patient and work to exterminate all you can find. Stink bugs can be particularly hard to remove.

Instead of trying pesticides, you can manually search on the plants for bugs and eggs. Eggs are typically found hiding on the underside of leaves. Kill all that you find.

As for disease issues, it’s best to just remove the affected plants from the garden and throw them away. Don’t compost them as it increases the risk of disease transfer when you use the compost.

The best treatment, however, is optimal growing conditions. Keep your soil healthy, sterilize all garden tools regularly, and apply organic fertilizers to keep your crops healthy. Keep the spacing between plants far enough to allow ample airflow.

As for the affected tomatoes that have white spots, you can simply cut off the white area before eating or preserving. None of these issues will affect you if you consume them, but they can affect the flavor of the tomato. Cut it out and throw it away. It’s as simple as that!

Frequently Asked Questions

1. Is It Safe To Eat Tomatoes With White Spots?

Yes, but the best idea is to cut off the affected area so the flavor isn’t affected. None of the common causes of white spots on tomatoes will harm you if you eat them.

2. How Do You Stop White Spots On Tomatoes?

It depends on the cause of the white spots. Go through the list above and find out which fits your symptoms. When it doubt, remove the affected tomatoes or the whole plant if it is widespread.

3. What Does Sunburn Look Like On A Tomato Plant?

Sunscald is a discolored spot on the tomato skin that appears yellowish-white. It is seen on the exposed side of the tomato where the sun reaches. E

Reduce pruning or use shade cloth if the issue is recurring.

4. Can You Eat Tomatoes With Sunscald?

Yes, simply cut out the affected area before eating and it’ll be just fine!

5. How can you evaluate and manage fungal disease in tomato plants?

To accurately evaluate and identify fungal disease in your tomato patch, you must first familiarize yourself with the types of fungus that typically attack tomatoes. Knowing how these fungi spread( e.g. through wind and rain) and develop will help you recognize and prevent conditions that promote fungal growth. Providing just the right environment for your tomato plants and taking steps to mitigate potential fungal infections can go far toward preventing loss of plants and fruits.

6. How can understanding fungal spread and reproduction help with mitigation of tomato plant disease?

When you understand that fungus is very likely to spread through inclement weather, you can take steps to protect your tomato patch before big storms. Knowing how fungus spreads and replicates can also inform your decisions about plant placement and pruning, watering schedules, preventative treatments and even plant choice. For example, if you live in an area that is particularly prone to a specific type of fungus, you can choose varieties that have been developed to resist that fungus.

7. What are some of the worst fungal diseases that threaten tomato plants?

When dealing with white spots on tomatoes, you are very likely to be dealing with one or more of these fungal diseases:

• Anthracnose manifests as circular water-soaked depressions or dips on ripe tomatoes. They are typically about a quarter inch in diameter and have black fungal structures (microsclerotia) just below the skin surface.
• Septoria leaf spot causes small, round spots with dark centers and light borders on the leaves. These spots may also have tiny black specks (pycnidia) in the center.
• Buckeye rot is characterized by large, firm, dry, sunken lesions on the fruit with concentric rings, resembling a buckeye. These lesions can extend into the tomato flesh.
• Early blight appears as circular irregular black or brown spots on older leaves, forming a distinct target pattern. Severe infestations can lead to defoliation, reducing fruit yield and causing sunscald injury.
• Late blight symptoms include dark, water-soaked lesions on leaves, often with a white, fuzzy growth on the undersides during humid conditions. This disease can rapidly spread and affect the entire plant, leading to foliage collapse and fruit decay.

8. What are some varieties of tomato plants that are resistant to fungal infection?

When selecting tomato varieties with resistance to fungal infections, it’s a good idea to look for those labeled as “disease-resistant” or “resistant to common tomato diseases.” Here are some popular varieties known for their fungal resistance:

• Iron Lady is resistant to early blight, late blight, and some other diseases. This cultivar produces medium-sized, round, red tomatoes.
• Jasper is resistant to late blight and early blight. This cultivar produces small, cherry-sized tomatoes with excellent flavor.
• Mountain Magic resists early blight, late blight, and some other diseases. This cultivar produces small, round, red tomatoes.
• Mountain Merit is resistant to early blight and late blight. This cultivar produces large, round, red tomatoes.
• Defiant is known for its resistance to late blight. This cultivar produces medium-sized, round, red tomatoes.
• Legend is resistant to late blight. This determinate variety produces medium-sized, round, red tomatoes.

9. How can you provide the right environment to help prevent fungal infection in tomatoes?

In addition to choosing fungus resistant varieties of tomatoes, you must establish good cultural practices. These include:

• Avoiding overhead watering
• Practice proper sanitation
• Remove old plant debris
• Provide good ventilation
• Shelter from high winds
• Use cover crop mulches
• Provide ample sunlight
• Practice crop rotation
• Use proper spacing

Even with resistant varieties, an ideal environment is crucial for preventing fungal infections in tomatoes.

10. Why is crop rotation important in reducing tomato diseases?

Crop rotation helps reduce disease. By planting tomatoes in new locations away from areas where tomatoes, eggplant, potatoes, or peppers have previously grown, you can minimize the risk of soil-borne fungi establishing itself in the soil.

11. What does the term, “altering the microclimate” mean in regard to care of tomato plants?

This is another way of discussing providing the right environment for your plants. When you alter the microclimate in your garden you are providing the best environment to nurture your tomato plants. This term also encompasses practices such as staking or caging as needed to keep your plants off the soil and establishing a morning watering routine that allows plenty of drying time. All of these practices combine to create less favorable conditions for fungal growth. These practices, combined with disease-resistant varieties, might mitigate the need for fungicides.

12. Should fungicides be used proactively in tomato gardening?

Proactive use of fungicides can be part of an integrated pest management (IPM) strategy. If you’ve had issues with fungal diseases in the past or if your garden tends to be humid and warm, applying fungicides preventively can help protect your tomato plants. If you prefer organic gardening, there are organic fungicides available that can be used preventively. Copper-based fungicides are a common choice for organic gardeners. Remember that while fungicides can be a useful tool, an integrated approach that includes disease-resistant varieties and good gardening practices can often provide effective control.

13. What if you don’t have time to hand water your tomato plants in the morning?

Set up a soaker hose on a timer. Soaker hoses are excellent additions to any garden for several reasons. First, they save a great deal of water. When you use a sprinkler, or even hand water, quite a bit of water is lost to evaporation. Second, by slowly delivering just the right amount of water directly to the soil around your tomato plants, you eliminate the possibility of creating a friendly habitat for fungus on your plants’ leaves and stems.

14. How can cover crops or mulches help prevent fungal infections in tomato plants?

When you place a mulch material, such as straw or composted leaves over the soil around your plants, your growing tomatoes cannot come in contact with bare soil. This helps prevent soil borne fungi from migrating into your fruits. The same is true of low-growing cover crops, such as clover, which not only protect the soil, help preserve moisture and prevent fruit from coming in contact with bare soil, they also improve the nitrogen content of the soil.

Good Luck With Your Tomatoes

Treating white spots on your tomatoes shouldn’t be an issue season after season. Follow the tips laid out in this article and you can still harvest tomatoes with white spots to consume while reducing the risk for recurring issues in the coming growing seasons. Have you found foolproof ways to stop white spots in your tomatoes?