Oedema is a physiological problem. Symptoms are usually seen on the lower side of leaves, but may occur on any part of the plant. Watery blisters or gall-like structures form, and later turn dark brown or yellow. They may become somewhat corky in appearance. The later stages may resemble rust diseases. Oedema often occurs when soil temperatures are higher than air temperatures and soil moisture and relative humidity are high. Mechanical injury to leaves, such as that caused by insect feeding, windblown soil, or chemical injury, may also result in oedema.

Management Options

Non-Chemical Management

Control insects (especially aphids) which feed on leaves.
Provide proper culture, taking particular care to avoid overwatering.
Protect young plants from windblown soil by sprinkling during high winds.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

None recommended

Images

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Caption: Oedema on geranium Photo by: R.S. Byther

WSU Extension

Hortsense