Description
Oedema, also known as edema, affects houseplants and some outdoor herbaceous plants. This condition is not caused by an insect or disease, but by a buildup of water in the plant. Oedema usually develops in plants that are overwatered and growing in a cool, humid atmosphere. Under these conditions, water is absorbed rapidly from the soil, and lost slowly through the leaves. The excess water that builds up in the plant causes cells to burst. Water-soaked spots or pale green blisters or bumps form on the leaves and stems. Eventually these bumps and spots develop into reddish brown corky ridges and spots. Some of the badly affected leaves may turn yellow and drop off.
Control
Oedema is not a serious condition in itself, but often indicates an overwatering problem. Eliminate oedema by planting in well-drained soil and watering properly. (For information on proper watering, see About Watering; for information on improving soil drainage, see Soil Types, Soil Structure, Groundwater.)
