Learn what Septoria leaf spot is and how to identify, treat, and prevent it whengrowing tomatoes.
What Is Septoria Leaf Spot?
The disease becomes more prevalent when the garden has warm, humid conditions.
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Symptoms of Septoria leaf spot are often confused withearly blight.
Septoria leaf spot appears as lesions on older leaves dotted with tiny brown-black dots.
Early blight shows as larger, slightly sunken lesions embedded with concentric rings.
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A yellow halo may surround the spot.
As the disease develops, the spots will get larger and may merge.
This is one of the symptoms that distinguishes Septoria leaf spot from other leaf-spotting diseases.
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The good news is that it rarely affects the fruits.
If untreated, Septoria leaf spot causes the leaves to turn yellow and eventually dry out and fall off.
Without leaves, the plant will not continue producing and maturing tomatoes.
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They can travel great distances in hopes of finding those conditions.
If caught early, it can be controlled.
But note that Septoria leaf spot spreads rapidly.
Wash your hands and cutting tools thoroughly before youprune tomato plantsthat are not infected.
Begin spraying as soon as the first symptoms appear and follow the label directions for continued management.
One of the least toxic and most effective is chlorothalonil (sold as Fungonil and Daconil).
Given the ideal conditions, it is prevalent and will venture to take hold in your garden.
Keep plants strong and improve your plant’s growth by using the correcttomato fertilizer.
Thoroughly processingthe tomato seedsyou are saving will also help rid the seeds of lingering diseases.
Start With a Clean Garden
Dispose of all affected plants.
Avoid Overhead Watering
Water aids the spread of Septoria leaf spot.
Water the plant at the base only to keep it off the leaves as much as possible.
Of course, keeping the rain off your plants is impossible, but every little bit helps.
Provide Room For Air Circulation
Leaveproper spacingbetween your tomato plants so there is good airflow.
Stake them so they are not touching the ground and not all bunched together.
Good air circulation is essential during damp and rainy periods.
Reapply weekly, in the morning or evening, to help your plants stay healthy.
But if possible, plant your next crop in a different area of your garden.
Septoria leaf spot is not the only problem that produces discolorations on tomato leaves.
Other culprits could be anthracnose, fusarium wilt, verticillium wilt, canker, orpests like thripsand hornworms.
To treat it, you’ll need to determine which problem you have causing the black or brown spots.
Leaf spot does not go away on its own.
Neem oil is another option to control Septoria leaf spot.
These fungicides and neem oil can only prevent the spread of the disease, not cure it.
University of Maryland Extension.
Early Blight and Septoria Leaf Spot on Tomatoes.University of Kentucky.
Septoria Leaf Spot.West Virginia University Extension.
Tomato Plant Diseases and How to Stop Them.USDA.
