Plant Problem Diagnosis Key / Growing conditions
Blossom-end rot
A calcium shortage in the fruit, not usually in the soil. Fruit gets calcium only with the water it draws, so uneven watering, root damage, salty soil and heavy ammonium or potassium feeding cut the supply.
Signs
- A dark, sunken, leathery patch on the bottom (blossom end) of tomato, pepper, squash or watermelon.
- The first fruit of the season most often.
- No fuzz or ooze unless secondary rot moves in.
What favors it
Uneven watering, drought then flood, root damage, high ammonium or potassium feeding, salty soil, and fast early growth.
Prevention
- Water evenly and mulch.
- Lime acidic soil per a soil test; most soils hold enough calcium.
- Avoid heavy ammonium, urea or potassium feeding.
Crops it shows up on
Tomato, pepper & eggplant; Cucumber, squash & melon.
Often confused with
Sources
- Blossom End Rot on VegetablesUniversity of Maryland Extension
- Blossom-End Rot of Tomato, Pepper, and WatermelonNC State Extension
- Tomato disordersUniversity of Minnesota Extension
Treatment by crop
Cultural, biological and chemical options in the order to use them, and notes written for each crop.
Identification is free. Treatment is on the Home and Pro plans.
Questions in the key that lead here
- Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
No, only damage or discoloration - Where is the problem?
Fruit, flowers or buds - What is wrong with the fruit or flowers?
Dark, sunken, leathery patch on the bottom of the fruit
Not a match? Start the key or describe what you see.
More photos
More from university Extension: search Extension pages on blossom-end rot, or find a plant diagnostic lab through your state's Extension.
Other growing conditions
- Blossom drop
- Cold and frost injury
- Construction and root damage
- Drought stress (underwatering)
- Edema (oedema)
- Fruit cracking
- Girdling roots and a buried root flare
- Heat and light stress
- Herbicide injury
- Leaf scorch and drought stress
- Light bleaching
- Mower, trimmer and animal injury
- Normal fall needle drop
- Not enough light (stretching)
- Overwatering (low root oxygen)
- Road salt injury
- Southwest injury (winter sunscald and frost cracks)
- Sunscald
- Transplant shock
- Winter burn of evergreens