Calcium deficiency
A shortage of calcium reaching new growth and fruit, causing distorted young leaves, brown leaf tips on lettuce and cabbage, and sunken spots on fruit.
Also known as: Tip burn, Bitter pit
Symptoms and identification
New leaves are small, crinkled, cupped or have brown dead edges, and growing tips may die. Lettuce and cabbage show brown, dry inner leaf edges called tip burn. Apples develop small sunken spots, called bitter pit, and tomatoes and peppers get blossom end rot.
Causes
Calcium moves only in the water stream, so the problem is usually uneven watering, fast growth, drought, root damage or too much nitrogen, potassium or magnesium, not a lack of calcium in the soil. Very acidic soil can also be low in calcium.
Organic treatment
Water evenly and deeply. If a soil test shows low calcium, add lime or gypsum before planting. Calcium sprays on leaves and fruit give limited help and work best as a preventive.
Prevention
Keep soil evenly moist with mulch and regular watering, do not overfeed with nitrogen, test soil pH and lime acidic soil. Choose varieties that are less prone to tip burn.
Chemical treatment (use with care)
A foliar calcium spray, such as calcium chloride or calcium nitrate, applied as the label directs, can help prevent problems in susceptible crops but does not cure existing damage.