Early Blight Alternaria - Treatment For Tomato Plant Leaf Spots And Yellow Leaves

Tomato Plant Affected by Alternaria Leaf Spot Fungus
alternaria tomato
(Image credit: Rupert Anand Yumlembam, CAU, Imphal, Manipur, India, Bugwood.org)

If you have noticed tomato leaf spots and the lower leaves turning yellow, you may have tomato early blight alternaria. This common tomato disease causes damage to the leaves, stems, and even the fruit of the plant. Keep reading to learn more about what causes tomato early blight alternaria and how to treat leaf spot.

What Causes Tomato Leaf Spots?

Alternaria Alternata, or tomato early blight alternaria, is a fungus that can cause cankers and plant leaf spots on tomato plants. It normally occurs during hot weather when there has been a significant amount of rain and humidity. Plants that have been damaged are particularly susceptible to being infected by tomato early blight alternaria. When a plant is infected with Alternaria Alternata, it will normally appear first on the lower leaves of the plant in the form of plant leaf spots that are either brown or black. These tomato leaf spots will eventually migrate to the stem and even the fruit of the tomato. These spots are actually cankers and can eventually overtake a plant and kill it.

Treatment for Tomato Plant Leaf Spots Caused By Alternaria Alternata

Once a plant is infected with tomato early blight alternaria, a fungicide can be sprayed on the plant. This can help reduce the damage from the plant, but frequently this will only lessen, not eliminate the problem. The best way to treat leaf spot on tomatoes is to make sure it doesn't occur in the first place. For future plantings, make sure the tomato plants are far enough apart. Also, don't water the plants from overhead; use drip irrigation instead. If you find Alternaria Alternata in your garden, make sure not to plant any other plants from the nightshade family in that spot for at least a full year. Destroy any tomatoes that have tomato leaf spots. Do not compost tomato plants with plant leaf spots, as this can re-infest your garden next year with tomato early blight alternaria. Again, the best treatment for tomato plant leaf spots is to make sure that you don't get it in the first place. Proper care of your tomato plants will make sure you avoid the dreaded yellow leaves and leaf spots that come with Alternaria Alternata.

Heather Rhoades
Founder of Gardening Know How

Heather Rhoades founded Gardening Know How in 2007. She holds degrees from Cleveland State University and Northern Kentucky University. She is an avid gardener with a passion for community, and is a recipient of the Master Gardeners of Ohio Lifetime Achievement Award.

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