Tipburn on lettuce
A physiological disorder caused by calcium running short in the youngest leaves when the plant grows faster than it can move calcium around. It is not infectious and does not spread to other plants.
Symptom photos
Symptoms
- Brown, dried edges on the youngest leaves in the heart of the rosette
- A glassy, water-soaked leaf margin just before it browns
- Symptoms only on young leaves, with older ones staying healthy
- No fungal bloom and no unpleasant smell
- Secondary rotting of the damaged margins
What it does to the crop
- Unmarketable heads where symptoms are severe
- The need to trim off damaged leaves
- Secondary bacterial infection and gray mold in the damage
- Shorter shelf life after cutting
What encourages it
- Rapid growth in high temperature and high humidity
- Uneven watering and swings in soil moisture
- Too much nitrogen and potassium
- High humidity limiting transpiration
Prevention
- Water evenly and avoid swings in moisture
- Keep nitrogen feeding moderate
- Ventilate the tunnel to bring humidity down
- Grow tolerant varieties, especially in summer
- Foliar feed with calcium as the head starts to form
⚠️ Before you reach for a spray
This atlas is informational and still growing — different diseases can look almost identical. Confirm the diagnosis and read the product label before applying any plant protection product. If you are unsure, ask your local extension or advisory service.
Keep the disease atlas with you in the garden
In the app you can identify a disease from photos, work out the spray dose for your own bed and log the treatment in your task calendar. Free, no sign-up, works offline.
Open the atlas in the app →