What's Wrong With My Tomato Plant? A Visual Symptom Guide
Yellow leaves, brown spots, and drooping stems can point to different tomato problems. Start with four clues: which leaves changed first, what the damage looks like, how fast it spread, and whether the soil is wet or dry. Then check the leaves, stems, and fruit for more evidence.
Step 1: Find where the problem started
| First place you see damage | What to check next |
|---|---|
| Lower, older leaves | Leaf spots, yellowing between veins, soil splash, and normal aging. |
| New growth | Distorted leaves, insects, recent spray drift, and stunted growth. |
| One side or one branch | Stem damage, root problems, and wilt diseases. |
| The whole plant | Soil moisture, heat, root health, and recent changes in care. |
| Fruit | Dark ends, dark spots, cracks, and insect damage. |
Location is a clue, not a diagnosis. More than one problem can affect the same plant.
Step 2: Match the symptom
Why are my tomato leaves turning yellow?
A few old leaves can yellow as a plant grows. If yellowing spreads, look at the pattern before you add fertilizer.
| What you see | Useful next check |
|---|---|
| Lower leaves turn yellow and develop dark spots | Compare early blight, Septoria leaf spot, and bacterial spot. |
| Yellow areas form between green veins on older leaves | Check for a possible magnesium shortage, then review soil and feeding history. |
| Many leaves yellow while the soil stays wet | Check drainage and roots before watering again. |
| Leaves yellow and wilt while the soil is dry | Water the root zone and watch for recovery. |
Leaf color alone cannot tell you which nutrient a tomato plant lacks. See the University of Minnesota’s guide to tomato leaf spots for photos of common lookalikes.
What causes brown spots on tomato leaves?
| What you see | Possible cause | What to look for |
|---|---|---|
| Larger dark spots with rings, often on older leaves | Early blight | Yellow tissue around spots and damage that moves up the plant. |
| Many small spots with pale centers and dark edges | Septoria leaf spot | Tiny dark dots inside older spots. |
| Small dark spots without a clear ring pattern | Bacterial spot or speck | Spots on fruit, recent wet weather, and nearby affected plants. |
| Fine pale specks that turn bronze | Spider mites | Tiny mites or webbing under leaves. |
Early leaf spots can look alike. University of Minnesota’s tomato spot guide shows the details. A local plant clinic can test a sample when the answer changes what you need to do.
Why are my tomato leaves curling?
Older leaves sometimes roll upward during heat or other stress while the plant keeps growing. This is called physiological leaf roll. Check the soil and new growth before you treat it. UC IPM’s leaf roll guide explains this pattern.
Small, twisted new leaves with yellowing or stunted growth need closer attention. Insects, herbicide drift, and viruses can produce overlapping signs. UC IPM’s tomato yellow leaf curl guide describes one possible viral cause. A curled leaf by itself does not prove a virus.
Why is my tomato plant wilting?
Feel the soil a few inches below the surface. Dry soil points to a water shortage. Wet soil can point to poor drainage or damaged roots. A plant can also wilt during strong heat while its soil remains moist. If one side stays wilted after the heat passes, ask a local extension service about a stem or root problem.
Why do my tomatoes have black bottoms?
A dark, sunken patch at the blossom end of a tomato is often blossom-end rot. Uneven water supply can limit calcium movement into the fruit, even when the soil contains calcium. Keep watering steady and avoid adding calcium without evidence of a soil shortage. See University of Minnesota’s tomato disorders guide.
Step 3: Check under the leaves
Turn over several affected leaves. Look for insects, eggs, pale feeding marks, and fine webbing. UC IPM’s spider mite guide shows the signs of mite damage. Also check stems and fruit. A close photo of the leaf underside can help you or a local expert find pests that a full-plant photo misses.
Take photos that help
Take one photo of the whole plant and one close photo of each symptom. Include healthy and damaged leaves when you can. Record when the problem started, recent weather, watering, and any spray or fertilizer use. These details help separate problems that look alike in one image.
Do not treat a photo match as proof. Early blight, Septoria leaf spot, and bacterial spot can overlap. Wilt can start in roots that the camera cannot see. If damage spreads fast, affects many plants, or changes your treatment choice, contact a local extension service or plant clinic.
Where PlantLab fits
PlantLab’s tomato model is in internal testing and is nearing live production. Tomato diagnosis is not available to the public yet. Read the earlier tomato development update for background, or visit PlantLab for product updates.