Early Blight

• Dark brown to black spots with concentric rings (target-board or bull's-eye pattern) on leaves
• Spots usually begin on older, lower leaves and move upward
• Yellow halo around the dark lesions
• Infected leaves yellow completely and drop, starting from the bottom of the plant
• Dark, sunken lesions may also appear on stems and fruit near the stem end

Alternaria solani overwinters in infected plant debris and soil. Spores are spread by wind, rain splash, and irrigation water. Infection tends to start on older foliage when plants are under any stress — drought, high nitrogen, or crowding. Warm temperatures (75-85°F) and wet periods favor rapid spread. The fungus is endemic in most vegetable gardens and will recur whenever conditions are favorable.

1. 01Mulch around plants at planting to prevent soil splash onto lower foliage — two to three inches of straw works well
2. 02Water at the base of plants, not overhead, and water in the morning so foliage dries quickly
3. 03Remove infected leaves as soon as they appear and dispose of them — do not compost
4. 04Stake or cage plants to improve airflow through the canopy
5. 05Apply copper-based fungicide or chlorothalonil preventively when conditions favor disease — before symptoms spread to upper leaves
6. 06Rotate solanaceous crops to a different bed each season
7. 07Plant disease-tolerant varieties (look for 'A' in disease-resistance codes)

If this keeps happening in your garden, the single most effective change is often the seed packet. These varieties carry documented resistance.

If early blight is defoliating plants completely before fruit matures despite fungicide applications, an extension plant pathologist can confirm whether Alternaria alternata or another species is involved and advise on a more targeted spray schedule.

• Early Blight of Tomato— University of Minnesota Extension
• Early Blight— Ohio State University Extension