Edema
Water imbalance (physiological disorder, not pathogenic)
Overview
A physiological disorder caused by excess water uptake relative to transpiration, resulting in raised, blister-like bumps on leaves and stems that may burst and become corky.
Symptoms
Raised, blister-like bumps on leaf undersides and stems. Bumps may burst and become tan, corky, or scab-like. Most common on lower leaves. Does not spread to other plants. Often occurs in cloudy, humid conditions.
Environmental Conditions
Humid
Prevention
Avoid overwatering, especially in cloudy weather. Ensure good air circulation. Increase light levels. Reduce humidity. Space plants adequately.
Management
Reduce watering frequency. Improve air circulation and ventilation. Increase light exposure. Affected leaves will not recover but new growth should be normal. Not contagious.