Black Rot on Dianthus Seedlings: Cause and Cure

Black, crispy leaf tips on 4-day-old dianthus = black spot fungus, triggered by high humidity (saran wrap) + heat mat.

Treatment

• Spray sulfur-based fungicide every 7–10 days.
• Remove affected leaves promptly.
• Increase airflow: use vented dome, remove wrap after germination.
• Consider dropping heat mat; room temp often sufficient.

Prevention

• Use sterile soilless mix (peat/vermiculite/perlite).
• Clean containers.
• Ventilated dome > plastic wrap.

Restart if severe; conditions favor disease.