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Friday - September 11, 2009

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Caterpillars on Mountain laurel in Austin
Answered by: Barbara Medford

QUESTION:

One of our 18+ year old Texas Mountain Laurels seems to be in distress this year. We treated it for caterpillars this Spring but many of the new leaves had been eaten by then. I recently started watering it when it seemed "droopy" during the 100+ temps we were having here in Austin over the summer. It has not been fertilized in several years, if at all. Do you have any suggestions for helping it recover? Thank you.

ANSWER:

This is the second question in a few days about the caterpillars in Central Texas on the Mountain Laurel. We are going to take the liberty of simply quoting that answer. One extra note on your question, about fertilizing: this is a native plant in its native habitat and should not need fertilizer. It is already adapted to the soils and the climate in this area. Further, your plant is under stress, and no plant that is stressed should be fertilized. Hopefully, the little bit of rain we have had in Austin in the last few days is a forerunner of more to come. We can't say for sure that the severe heat and drought has contributed to the caterpillar infestation of the Mountain Laurels in our area, but it sure hasn't helped. Now, from our previous answer:

"Sophora secundiflora (Texas mountain-laurel) is ordinarily considered pretty pest and disease free. However, it can certainly be attacked by caterpillars, and prompt action helps the tree survive. Read this Landscape Integrated Pest Management article from Texas A&M AgriLIFE Extension Genista caterpillar on Texas Mountain Laurel. It explains the steps that need to be taken. You must try, since it is kind of late in the season, to get as many of the caterpillars off as you can. The treatment suggested in this article is really only effective early in the "chewing season" when the moth larvae are actively eating the leaves. The tree needs to be given the chance to revive and grow a few more leaves before it goes dormant, because the whole tree, and its roots, are dependent on the leaves to manufacture food for the plant through photosynthesis. In an active growing season, no leaves, no food, and the tree could easily die. And if the tree survives and comes back next Spring, start watching early for the eggs of the moth mother on the leaves. Getting them off before the caterpillars ever hatch is the best prevention, and the most chemical-free."