Identifying and Treating Tomato Blight in August

Tomato blight is a gardener’s nightmare—especially in humid, wet August weather. It can destroy plants and fruit fast, even after months of hard work. Early identification and fast action are the keys to saving your crop. Here’s how to spot blight on tomatoes, what to do if you find it, and the best ways to minimize damage during August’s peak risk.

What is Tomato Blight?

• Late blight (Phytophthora infestans) is the most serious, often arriving on humid air or after summer storms.
• It affects leaves, stems, and fruit—rapidly causing brown, greasy patches, wilting, and fruit rot.
• Early blight (Alternaria solani) causes brown spots with concentric rings, mostly on the lower leaves.

How to Identify Blight in August

• Leaves: Pale green, water-soaked or greasy patches that quickly turn brown or black. Leaf edges curl and blacken, often with a wire-thin border between healthy and dying tissue.
• Stems: Brown or black streaks or rot.
• Fruit: Firm, dark, sunken patches that spread and soften in rain or humidity.
• Rapid Spread: Whole plants can collapse in a few days during wet, warm weather.

What to Do If You Find Blight

1. Act Fast:
   • Remove and bag all affected leaves and stems. Do NOT compost—put in household waste or burn if permitted.
2. Pick Healthy Fruit:
   • Harvest all undamaged tomatoes, even if green. Ripen indoors on a sunny windowsill.
3. Improve Airflow:
   • Remove lower leaves and side shoots to let air around the base and fruit trusses. Space plants if growing in pots.
4. Water at Soil Level:
   • Avoid wetting leaves. Mulch to keep splashes off foliage.
5. Remove Entire Plants if Necessary:
   • If infection is severe, pull and destroy the whole plant to protect the rest of your crop.
6. Clean Tools:
   • Disinfect scissors, canes, and gloves after contact with sick plants.

Prevention and Future Protection

• Water only in the morning and only at the base.
• Mulch well to stop soil splashing onto leaves.
• Grow resistant varieties and rotate beds each year.
• Use copper-based sprays or organic fungicides as a preventative (check local organic regulations).

Final Tip

• Blight spreads fastest in damp, still air. Prune and space for ventilation, and check your plants daily during high-risk August weather.