Q: What are these growths on my ligustrum and viburnum?

A: The growths on your plants appeared to be Oedema. This condition occurs when roots take up water faster than it can be used by the plant or transpired through the leaves. Water pressure then builds up in the internal cells of the leaf causing them to enlarge and form tiny swollen blister­like areas.

Oedema appears as small, sometimes corky blisters which will eventually harden to form white, tan, or brown wart­like corky bumps on the lower leaf surface. In severely affected plants these corky growths also form on petals, petioles, and stems. As injury continues, leaves turn yellow, droop, and fall off. Plants may become spindly and growth ceases.

This condition most often occurs on drought tolerant plants when we receive large amounts of water (rain) during short periods of time. In addition to the rain we received with the hurricane Fay we also had several rain showers in which did the water not drain quickly. There is no chemical spray to correct the damage on the leaves. Some light pruning to damaged areas might help the appearance of the shrubs or trees. However, as long as the leaves remain green they continue to produce carbohydrates for the plant and are therefore useful. Be careful not to remove too much of the plant canopy as this will cause further stress.

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Posted: July 9, 2017


Category: Home Landscapes
Tags: Oedema


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