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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Friday - May 30, 2008

From: Austin, TX
Region: Southwest
Topic: Pests, Shrubs
Title: Sap drips from Sophora secundiflora
Answered by: Barbara Medford

QUESTION:

We have an old Mountain Laurel (sophora secundiflora) about 20 ft tall. It blooms pretty well and seems healthy. We are wondering why it drizzles a non-sticky sap in tiny drops. Hold out your hand and you think it's starting to rain. We hope it's a sign of good health, and we are very curious why the plant does this.

ANSWER:

That sounds an awful lot like aphids. Anyone who has ever had to park their car under a tree that has aphids can talk to you about the mess it makes. And every reference to Sophora secundiflora (Texas mountain-laurel) that we found said that it was not threatened by any serious pests and diseases. Don't you hate when they say that and you KNOW there is a problem?

Getting back to the possibility of aphids. The University of California Integrated Pest Management has an excellent website on aphids. In the article, you'll find ways to identify the presence of the little bugs, when they may be more or less numerous, and non-chemical ways to treat them without damaging the beneficial bugs that eat aphids. One note you will particularly appreciate is that aphids do not do well in very hot temperatures. So, since it looks like this is going to be a really hot summer, maybe that's a good thing.

We found another critter that targets Mountain laurel, but is not considered serious except in very young, new trees. The Maricopa (Arizona) County Extension Service has published an article on the Sophora worms, Uresiphita reversalis.

 

 

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