Early Tomato Blight

Early Tomato Blight

Early blight is one of the most common diseases affecting tomatoes in community gardens. It’s caused by the fungus Alternaria solani and can significantly reduce yield if not managed properly.

Identification

Early blight typically appears as:

  • Dark brown spots with concentric rings on older, lower leaves
  • Yellowing of leaves around the spots
  • Stem lesions that are dark and sunken
  • Fruit rot with dark, leathery spots near the stem end

The disease usually starts on the lower leaves and progresses upward through the plant.

Prevention

Cultural Practices

  • Crop rotation: Avoid planting tomatoes in the same location for 3-4 years
  • Proper spacing: Ensure good air circulation between plants
  • Mulching: Apply organic mulch to prevent soil splash onto leaves
  • Watering: Water at soil level, avoid wetting the foliage
  • Pruning: Remove lower branches to improve air circulation

Resistant Varieties

Choose tomato varieties with resistance to early blight when possible:

  • Mountain Fresh Plus
  • Iron Lady
  • Defiant PhR
  • Mountain Magic

Treatment

Organic Options

  1. Copper-based fungicides: Apply preventively before symptoms appear
  2. Baking soda spray: Mix 1 tsp per quart of water with a few drops of dish soap
  3. Neem oil: Apply in early morning or evening to avoid leaf burn
  4. Remove affected plant material: Dispose of in trash, not compost

Application Schedule

  • Begin treatments when plants are established (4-6 weeks after transplanting)
  • Apply preventive treatments every 7-14 days during humid conditions
  • Always follow label instructions for any fungicide

Garden Management

Sanitation

  • Remove and destroy infected plant debris at end of season
  • Clean tools between plants when working with infected material
  • Avoid working in the garden when plants are wet

Environmental Factors

  • Early blight thrives in warm, humid conditions
  • Most active when temperatures are 75-85°F with high humidity
  • Spores spread through wind, rain, and contaminated tools

When to Seek Help

Contact experienced gardeners or extension services if:

  • Disease spreads rapidly despite treatment
  • You’re unsure about proper identification
  • Multiple plants are severely affected

For questions about pest management in the Rosedale Community Garden, contact the Garden Teams through our member resources.