ข้อเท็จจริงสำคัญ

• Caused by calcium deficiency at the leaf tip — calcium transport requires transpiration
• Common in fast-growing, densely headed lettuces: butterhead, romaine, Boston types
• Occurs even when reservoir calcium levels are adequate
• Triggered by low VPD, high humidity, and insufficient airflow across the canopy
• Prevention: increase airflow, reduce humidity, space plants wider, use oscillating fans
• Some lettuce varieties are genetically tip-burn resistant — choose these for dense systems