Tomato Leaf Problems: Overwatering, Nitrogen Excess, and Disease Diagnosis

Follow-up to giant seed query: Tomato plants fruit well but leaves appear dehydrated—withered, shrunk, folded—yet feel fresh. Grower suspects over-fertilization, excessive sun, or disease.

Primary Suspects

1. Overwatering: Soggy soil reduces root oxygen, causing leaf curl/wilting despite moisture.
2. Excess nitrogen: Lush foliage, poor fruit set, leaf curling. Use fertilizer ratio ~10-30-20 (high P, low N).
3. Sun scald: Only if plants recently moved to full sun without hardening off (ruled out at 10+ days).

Diagnostic Steps

• Check soil moisture 2 inches down—should be moist, not wet.
• Review fertilizer: Switch to high-phosphorus tomato formula.
• Inspect for disease: Most tomato diseases affect fruit too. If fruit is clean, disease unlikely.
• Test soil for pH and nutrients if problems persist.

Corrective Actions

• Water deeply 1 inch/week (more in >90°F), not daily shallow watering.
• Apply water-soluble high-P fertilizer every 2 weeks.
• Mulch to stabilize moisture/temperature.
• Remove lowest leaves for airflow.

When to Seek Help

If plants decline despite corrections, take a sample to local nursery for lab diagnosis. Fungicides only if fungal disease confirmed.