01Yellowing leaves
| Possible cause | Colorado State | Clemson |
|---|---|---|
| Early blight | Colorado State University Extension says as early blight advances, the affected foliage fades to yellow, then browns and drops from the plant. Source: Tomato Early Blight · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
| Septoria leaf spot | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says when septoria spotting is heavy, the whole leaf yellows, dies, and falls away, usually starting with the lower foliage. Source: Tomato Diseases & Disorders · checked 2026-09-27 |
| Fusarium wilt | Colorado State University Extension says both fusarium wilt and fusarium crown rot on tomato start out the same way, with the older leaves turning yellow first. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | Clemson Cooperative Extension says leaves on just one side of the stem often go golden yellow first. Source: Tomato Diseases & Disorders · checked 2026-09-27 |
| Whiteflies and aphids | Colorado State University Extension says both of these insects turn leaves yellow and leave sticky honeydew behind. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
| Psyllids | Colorado State University Extension says psyllid feeding turns the foliage yellow while the veins take on a purple tint. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
02Spots on leaves
| Possible cause | Colorado State | Clemson | Wisconsin |
|---|---|---|---|
| Early blight | Colorado State University Extension says older leaves get brown to black spots with a target-like look. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | Clemson Cooperative Extension says early lesions show up as small brown spots scattered mostly on the plant's oldest leaves. Source: Tomato Diseases & Disorders · checked 2026-09-27 | No matching line in the Wisconsin pages we checked. |
| Septoria leaf spot | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says each spot has tiny black dots in its middle, which is where the fungus makes its spores. Source: Tomato Diseases & Disorders · checked 2026-09-27 | University of Wisconsin–Madison Extension says each septoria lesion develops a pale, whitish middle ringed by a noticeably darker edge. Source: Septoria Leaf Spot · checked 2026-09-27 |
| Bacterial spot | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says bacterial spot shows up as many small, oddly shaped, water-soaked marks scattered across the leaf. Source: Tomato Diseases & Disorders · checked 2026-09-27 | University of Wisconsin–Madison Extension says the spots can start out as small, round, wet-looking areas on the leaf. Source: Bacterial Spot of Tomato · checked 2026-09-27 |
03Curled or distorted leaves
| Possible cause | Colorado State | Clemson |
|---|---|---|
| Physiological leaf roll | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says this non-disease roll begins with leaflets cupping upward, then rolling lengthwise in toward the midrib. Source: Tomato Leaves Rolling? · checked 2026-09-27 |
| Tomato yellow leaf curl virus | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says leaves curl upward and come in small with yellow edges, the plant is stunted, and flowers drop. Source: Tomato Diseases & Disorders · checked 2026-09-27 |
| Curly top virus | Colorado State University Extension says curly top makes leaves roll and curl with a crinkled texture, and the whole plant looks stunted and dwarfed. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
| Weed-killer drift | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says drift from a nearby weed killer can leave tomato leaves rolling downward with twisted, distorted growth. Source: Tomato Leaves Rolling? · checked 2026-09-27 |
04Holes and chewed leaves
| Possible cause | Colorado State | Clemson |
|---|---|---|
| Tomato/tobacco hornworm | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says hornworms feed by stripping the leaves off tomato vines. Source: Tomato Insect Pests · checked 2026-09-27 |
| Flea beetle | Colorado State University Extension says flea beetles leave a scatter of tiny chewed holes or pits across the leaf surface. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
05Wilting or dying back
| Possible cause | Colorado State | Clemson |
|---|---|---|
| Fusarium wilt | Colorado State University Extension says cut the stem and you can see streaking in the water-carrying tissue along its whole length. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
| Bacterial wilt | No matching line in the Colorado State pages we checked. | Clemson Cooperative Extension says the plant wilts fast while its leaves are still green. Source: Tomato Diseases & Disorders · checked 2026-09-27 |
| Tomato spotted wilt virus | Colorado State University Extension says with spotted wilt virus the plant droops over time, but unlike other wilts the leaf tissue stays stiff rather than going limp. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
06Fruit, pods and tubers
| Possible cause | Colorado State | Clemson |
|---|---|---|
| Blossom end rot | Colorado State University Extension says blossom end rot first appears as pale tan, water-soaked spots right at the fruit's blossom end. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | Clemson Cooperative Extension says the first sign is a water-soaked patch on the blossom end of the fruit. Source: Tomato Diseases & Disorders · checked 2026-09-27 |
| Sunscald | Colorado State University Extension says sunscald shows up on fruit that has been left out in too much direct sun. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
| Catfacing | Colorado State University Extension says catfaced fruit comes out misshapen, with scars and holes at the blossom end. Source: Recognizing Common Tomato Pests, Pathogens, and Problems · checked 2026-09-27 | No matching line in the Clemson pages we checked. |
What to do about it. This site only covers how to recognize a problem. For what to do next, open the Extension page linked in the row: their advice is written for their region and is kept up to date by them.
Pages compared on this chart
- Tomato Early Blight, Colorado State University Extension (checked 2026-09-27)
- Recognizing Common Tomato Pests, Pathogens, and Problems, Colorado State University Extension (checked 2026-09-27)
- Tomato Diseases & Disorders, Clemson Cooperative Extension (checked 2026-09-27)
- Septoria Leaf Spot, University of Wisconsin–Madison Extension (checked 2026-09-27)
- Bacterial Spot of Tomato, University of Wisconsin–Madison Extension (checked 2026-09-27)
- Tomato Leaves Rolling?, Clemson Cooperative Extension (checked 2026-09-27)
- Tomato Insect Pests, Clemson Cooperative Extension (checked 2026-09-27)