DiseaseOther
Oedema
Small blisters and corky bumps on leaf undersides, caused when roots take up water faster than the leaves can release it.
Also known as: Edema, Corky leaf bumps
Symptoms and identification
Tiny water-soaked blisters appear on the undersides of leaves, then turn brown, corky and rough. Leaves may yellow and drop. It is common on geraniums, jade plants, peppers, tomatoes and ivy.
Causes
Warm, wet soil combined with cool, humid air and low light, for example overwatering during cloudy weather.
Organic treatment
Reduce watering and move the plant to a brighter, airier spot. Affected leaves will not recover, but new leaves will be normal.
Prevention
Water only when the soil needs it, improve airflow and light, and avoid watering in the evening during cool, cloudy spells.
Chemical treatment (use with care)
Not needed.