Edema/Oedema
Description Edema (oedema) is identified by watery blisters (swellings) that form along the leaf veins and typically occur on the undersides of leaves. Under severe cases, edema can cause leaf drop, spindly stems, and eventually halt plant growth. Edema is induced by high relative humidity, overwatering, and/or low light quality, causing the plant to take up more water than it can transpire. Because of this, edema is most commonly observed in greenhouses during prolonged cloudy weather.
Management To avoid edema, vent the greenhouse to reduce humidity and space plants apart to improve air flow and light penetration. Other methods include using of supplemental lighting during winter or prolonged overcast days and avoiding overwatering.
Timing
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Edema most commonly occurs in late winter in greenhouse production or during prolonged cloudy and humid weather.
