Tomatoes are a great backyard-garden vegetable many gardeners grow. Harvesting fresh tomatoes right from the plant is satisfying and rewarding.
However, as they grow, you could discover white spots appear on the leaves of your tomato plant; the leaves, as well as the tomatoes themselves, could be under threat. You may panic and wonder, what are the white spots on tomato leaves?
White spots on tomato leaves can result from powdery mildew, caused by insufficient sunlight, poor air circulation and high humidity.
Although powdery mildew rarely kills tomatoes, it can reduce your yield and affect tomato taste. In our guide, you can learn more about tomato plant problems and how you can fix powdery mildew. (Read Can You Freeze Green Tomatoes)
How Do You Treat White Spots on Tomato Plants?
Powdery mildew is a fungal disease that stems from several types of fungi. Such fungi thrive in areas that are dark, stagnant, and overly moist.
When humidity is high or your tomatoes don’t receive enough sunlight or air circulation, the leaves are a natural place for these fungi to grow and reproduce.
As a result, you often see powdery mildew white spots forming on the leaves of tomato plants. Powdery mildew will target younger plant leaves compared to older established plants.
You can find over-fertilization may contribute to powdery mildew. When tomatoes receive excess fertilizer, growth accelerates at faster rates where tomatoes produce new leaves, ideal for powdery mildew.
While fertilizing tomatoes contribute to higher yields, over-fertilization is counterproductive.
Treating tomato problems such as powdery mildew isn’t always successful, but the sooner you treat, and your leaves may have a better chance. (Learn When To Fertilize Tomatoes)
The first steps in treating powdery mildew are to prune any affected leaves. Once you prune these affected leaves, it helps stop the spread of powdery mildew to other plant areas. Besides this, it increases the air circulation through the plant, which is vital for good health.
If you discover many tomato plant leaves have signs of powdery mildew, make sure you only prune the most affected leaves. If you prune too many, you could damage or kill your tomato plant. Once you have pruned your plant, you can use a fungicide. (Learn How Far Apart to Plant Tomatoes)
Here are a couple of sprays to use on your exposed plants to help prevent powdery mildew. You can dust sulfur or copper on the leaves, yet these are better options for your plant’s foliage.
Neem oil is an organic fungicide that is ideal for treating powdery mildew. Besides being a great fungicide, neem oil is also an organic insecticide that can repel many kinds of insects like aphids, mealybugs, and whiteflies. All these tomato pests are harmful to tomato plants.
Spray neem oil onto any infected tomato leaves once per week until you see the symptoms subside.
- If you can’t find neem oil, you can try another alternative as one of the best to treat powdery mildew on your tomato leaves. Mix 2 parts milk to 3 parts water. Spray infected tomato leaves with the milk spray.
- Apply this weekly until related symptoms fade.
What Are the Little White Specks on My Tomato Plants?
You can spot white leaf color on your tomatoes. It may not be powdery mildew yet something else. It may be sun damage, cold, or a fungal disease.
One of the most common causes of leaves turning white is from transplanted seedlings or exposure to intense sunlight. While tomatoes need around 8-hours of sunlight per day, if the weather gets too hot, the leaves could wither and fall off when the plants are young. (Find the Best Soil For Tomatoes)
Your tomato plant requires direct sunlight for full and healthy growth; changes in the location from indoors to outdoors can shock them and cause your tomato leaves to turn white. Typically, this kind of sunlight damage appears as a border of white on the leaves of your tomatoes.
You can also see the leaves are curling, breaking, and there is minimal foliage on the plant. Winds can also increase this condition. Mature tomato plants that suffer from sunscald have fruits that blister or are papery. (Read Squash Leaves Turning White)
The solution for tomato plants with white leaves is to let them spend several days in the shade to harden off before going into your garden. Fungal Reasons for Tomatoes with White Leaves is a fungal disease and comes from over-watering, where wet soil stimulates fungal spores and leads to root rot.
Alternaria or Septoria leaf spot, which has black spots on tomatoes leaf surfaces surrounding the white blotches. New transplants need watering deeply for the first three days; you can water once per week based on your climate or even once every two weeks.
Doing this promotes deep root development and helps avoid fungal spores taking hold. If you have a fungal disease, try a fungicide made for tomatoes. (Read About the Life Cycle of The Tomato Worm)
How Do You Treat Tomato Leaf Spots?
Here are methods to go along with treating leaf spots, yet these are preventative measures for future planting.
Preventing powdery mildew is better than applying any treatment, so a few effective preventative measures are advisable to treat powdery mildew and ensure your tomato plant develop as they should.
Follow these steps to minimize the chances of powdery mildew infecting your tomato plant.
Spacing and Pruning
Poor air circulation is a prime reason for powdery mildew. Thus, good plant spacing is vital for preventing powdery mildew.
Tomato plants need to be spaced 18 to 24 inches apart from each other.
Overcrowding in your garden and your plants stop air circulating through them and thus making conditions perfect for powdery mildew to form. Give your tomato plant space to develop where they can get lots of airflow through the growing season. (Learn How Much Bone Meal For Tomatoes)
Insufficient lighting is another reason for powdery mildew. Make sure your tomato plants receive enough sunlight as a means of stopping powdery mildew.
Tomatoes need 6 to 8 hours of full sunlight for healthy growth. Tomatoes are sun-loving plants and should be grown in areas of full sun.