Cause This is a physiological disorder. High fertility and high temperatures aggravate the disorder. Research indicates it is caused by an imbalance of calcium. Water stress followed by a period of excessive growth and dry soil conditions favors development of tip burn.
Symptoms The margins or tips of leaves turn a light to dark brown. Symptoms can extend from a few small, brown spots on interior leaf edges to large areas of the leaf margin turning brown and eventually decaying. External symptoms usually are absent; inner whorls of leaves are usually affected.
Cultural control No completely effective controls are known.
- Soil samples should show adequate base saturation and adequate levels of calcium.
- Use adequate irrigation to avoid water stress conditions that would interfere with calcium movement to inner leaves.
- Applying nitrogen at levels as low as possible commensurate with adequate yields is helpful.
- Foliar applications of calcium may be of benefit.
Reference Koike, S.T., Gladders, P., and Paulus, A.O. 2007 Vegetable Diseases: A Color Handbook. St. Paul. MN: APS Press.