Diseases of lettuce(
Tipburn of lettuce is not caused by a pathogen but is thought to be a calcium deficiency. Factors that contribute to rapid growth of lettuce such as warm temperature, excessive nutrients, and increased light enhance tipburn in lettuce. Symptoms are dark brown spots near the leaf margin followed by marginal necrosis of leaves (photo 1) and of inner leaves (photo 2).
Applications of calcium are not effective for control in crisphead lettuce because of slow uptake in the plant, but may reduce tipburn in leafy varieties. Tolerant varieties of lettuce are available and should be planted in warm temperatures. Cultural practices that do not support rapid growth also reduce tipburn.
February 20, 2013