Edema
Edema is a physiological disorder where plants develop small, water-soaked blisters on leaves and stems due to excessive water uptake. This condition is often seen when environmental conditions favor rapid water absorption but slow transpiration.
What you see
Edema occurs when a plant absorbs water faster than it can transpire it, leading to cells bursting and forming blisters or bumps on the leaves and stems. This is typically a cosmetic issue and does not usually affect the overall health of the plant. The condition is more common in indoor plants or those in greenhouses where humidity levels are high and air circulation is poor. The blisters may initially appear translucent and water-soaked, but they can turn corky and brown as they age. This can be mistaken for a fungal or bacterial infection, but unlike these diseases, edema does not spread from plant to plant. Identifying edema involves observing the environmental conditions and the pattern of damage. Unlike diseases, edema is not contagious and will not spread through a garden or greenhouse. It is crucial to differentiate it from pathogen-induced issues to avoid unnecessary treatments.
Symptoms
- Water-soaked blisters on leaves
- Corky or scabby patches on stems
- Brown or rust-colored spots
- Blisters turning corky over time
Why it happens
Excessive water uptake combined with slow transpiration rates.
Conditions that favour it
- High humidity environments
- Poor air circulation
- Overwatering
- Rapid changes in temperature
- Low light conditions
Plants most affected
- Begonia
- Geranium
- Tomato
- Pepper
- Succulents
- Jade plant
How to correct it
Educational information only, and not a substitute for professional diagnosis. Identify the problem before treating it, and check that any product is registered for this plant and this use where you live.
Cultural control
- Improve air circulation
- Reduce watering frequency
- Increase light exposure
- Maintain consistent temperatures
Prevention
- Avoid overwatering
- Ensure proper drainage
- Use fans for air movement
- Monitor humidity levels
- Gradually acclimate plants to new environments