| Table 1: Key to the identification of tomato problems. |
| LEAVES |
| Purple leaves: |
| Leaves with purple veins and overall purplish tint. Early season, cool temperatures. No Insects present |
Phosphorus deficiency |
| Leaflets roll upward and develop a purplish color, especially along the veins |
Curly top virus |
| Yellowed leaves: |
| Slight distortion, purpling of veins. Zigzag stem and branching pattern. Check underside of leaves for Insects |
Psyllids |
| Infected plants turn yellow and soon stop growing |
Curly top virus |
| Small holes, approximately 0.5 mm |
Flea beetle |
| Chewing injury on leaves. |
Tomato/tobacco hornworm |
| Black or dark brown spots. Lesions have margins or concentric rings. Lower leaves commonly affected |
Early blight (Alternaria) |
| Spots on leaves with white or gray centers surrounded by dark black or brown margins |
Septoria leaf spot |
Honeydew produced and
white Insects fly away
black, rosy or green Insects present |
Whiteflies
Aphids |
| Leaf scorching. Check watering, ambient temperature, salts, etc. |
| No signs of insect or disease present. Check stems, roots and vascular system. |
| Vascular system discolored. See wilting section. |
| Distorted leaves: |
Curling, shoestringing, cupping and
herbicides applied recently
plants stunted, no herbicides applied |
Herbicide injury
Cucumber mosaic virus |
| Wilted leaves: (Check roots for rot and cut the stem to look inside the stem tissue.) |
| Vascular streaking evident along entire length of stem |
Fusarium wilt |
| Vascular streaking evident only in the crown (first 12 inches of stem) |
Fusarium crown rot |
| Lower leaves turn down, leaf edges brown |
Bacterial canker |
| Leaf spotting, concentric rings and margins may or may not be present, leaf tissue stiff, not flaccid |
Tomato spotted wilt virus/impatiens necrotic spot virus |
| No vascular streaking. Check roots and soil moisture. |
| Roots discolored, mushy. See root section. |
| STEMS |
| Black or dark cankers on stem. (Submit samples to a diagnostic clinic for confirmation) |
Early blight (Alternaria), tomato spotted wilt virus/impatiens necrotic spot virus, bacterial canker |
| ROOTS |
| Roots discolored, mushy. Check soil moisture and watering |
Root rot |
| FRUIT |
| Spots, circles or blotches: |
| Ring spots on fruit |
Tomato spotted wilt virus/impatiens necrotic spot virus |
| Dark pinpricks surrounded by a light, discolored
area on green fruit. These areas turn yellow or remain green on ripe
fruit. The tissue under the spots is white and spongy and remains firm
as the fruit ripens |
Stink bugs |
| White, leathery areas |
Sunscald |
| Blotches on the shoulder of the fruit |
Green/yellow shoulders |
| Small, white to yellow, raised blotches on fruit, often called bird's eye |
Bacterial canker |
| Distorted: |
| Yellowing or not, with necrotic areas or not |
Catfacing |
| Blossom end flattened and black |
Blossom end rot |
| Yellowing |
Psyllids |
| Ring spots on fruit |
Tomato spotted wilt virus/impatiens necrotic spot virus |
| Contact your Colorado State University
Cooperative Extension county office for more information or for help
identifying problems. |
