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 page, read 2026-09-27: Tomato Early Blight | 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 page, read 2026-09-27: Tomato Diseases & Disorders |
| 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | Clemson Cooperative Extension says leaves on just one side of the stem often go golden yellow first. Source page, read 2026-09-27: Tomato Diseases & Disorders |
| Whiteflies and aphids | Colorado State University Extension says both of these insects turn leaves yellow and leave sticky honeydew behind. Source page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | Clemson Cooperative Extension says early lesions show up as small brown spots scattered mostly on the plant's oldest leaves. Source page, read 2026-09-27: Tomato Diseases & Disorders | 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 page, read 2026-09-27: Tomato Diseases & Disorders | University of Wisconsin–Madison Extension says each septoria lesion develops a pale, whitish middle ringed by a noticeably darker edge. Source page, read 2026-09-27: Septoria Leaf Spot |
| 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 page, read 2026-09-27: Tomato Diseases & Disorders | University of Wisconsin–Madison Extension says the spots can start out as small, round, wet-looking areas on the leaf. Source page, read 2026-09-27: Bacterial Spot of Tomato |
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 page, read 2026-09-27: Tomato Leaves Rolling? |
| 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 page, read 2026-09-27: Tomato Diseases & Disorders |
| 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Tomato Leaves Rolling? |
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 page, read 2026-09-27: Tomato Insect Pests |
| Flea beetle | Colorado State University Extension says flea beetles leave a scatter of tiny chewed holes or pits across the leaf surface. Source page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Tomato Diseases & Disorders |
| 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | Clemson Cooperative Extension says the first sign is a water-soaked patch on the blossom end of the fruit. Source page, read 2026-09-27: Tomato Diseases & Disorders |
| Sunscald | Colorado State University Extension says sunscald shows up on fruit that has been left out in too much direct sun. Source page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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 page, read 2026-09-27: Recognizing Common Tomato Pests, Pathogens, and Problems | 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
- 2026-09-27 · Tomato Early Blight, Colorado State University Extension
- 2026-09-27 · Recognizing Common Tomato Pests, Pathogens, and Problems, Colorado State University Extension
- 2026-09-27 · Tomato Diseases & Disorders, Clemson Cooperative Extension
- 2026-09-27 · Septoria Leaf Spot, University of Wisconsin–Madison Extension
- 2026-09-27 · Bacterial Spot of Tomato, University of Wisconsin–Madison Extension
- 2026-09-27 · Tomato Leaves Rolling?, Clemson Cooperative Extension
- 2026-09-27 · Tomato Insect Pests, Clemson Cooperative Extension