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Wednesday - May 11, 2011

From: Georgetown, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Need to identify white powdery substance on Wisteria in Georgetown, TX.
Answered by: Jimmy Mills


My wisteria shrub has a white powdery substance over the wood base. I have tried spraying a fungicide on it but have seen no improvement. Any suggestions?


Usually, having white powdery substance on a plant brings thoughts of powdery mildew. This link to Colorado State University Extension talks about identifying the pest and has several suggestions for treatment. The University of California Integrated Pest Management Program is also a good source of information. You can also get help from the folks at the Williamson County office of Texas AgriLife Extension.

You didn’t tell me the species of Wisteria that you have, but there are at least three possibilities here in Texas; two that are natives and one that is non-native. Since the mission of the Lady Bird Johnson Wildflower Center is to increase the sustainable use and conservation of native wildflowers, plants and landscapes, we are all about encouraging native plants.

The native species in Texas are American Wisteria Wisteria frutescens (American wisteria) and Texas Wisteria (W. macrostachys ). However there are those that consider them to be the same species.

Although it is widely planted from Texas eastward in the US, the non-native Chinese Wisteria ( Wisteria sinensis) is considered an invasive species in Texas and many other states. There is a Japanese wisteria (W. floribunda) that is also considered an invasive species.

Wisteria frutescens




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