Native Plants

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Thursday - April 17, 2008

From: Round Rock, TX
Region: Southwest
Topic: Vines
Title: Red blister-like bumps on grapevine
Answered by: Barbara Medford and Joe Marcus

QUESTION:

I have just discovered red blister like bumps on a grapevine. It is on the leaves as well as the stems. What could this be? Will it harm only the grapevine or other plants as well? Thank you.

ANSWER:

We went to our Native Plant Database and found three vines that are native to Texas, and assume that you are growing one of these: Vitis mustangensis (mustang grape), Vitis monticola (sweet mountain grape), and Vitis rotundifolia (muscadine). Those red blisters are leaf galls. Common ones are called grape tomato gall, grape tumid gall, or grape tube gall. All of these are caused by midges (tiny flies). Minute wasps can also cause leaf galls on some plant species. This website from the Cornell University Integrated Pest Management Program on Grape Tumid Gallmaker has a great deal of information on the problem and solutions. If, as you read this article, it appears to you the dates of appearance of the galls are a little out of whack with your observations, remember that Cornell University is in New York - their Spring comes later and Fall comes earlier.

Although these galls are unsightly, they do not interfere with grape production unless they are numerous. We could find no indication that the infestation might spread to other types of plants. If you feel you might need some sort of advice on controls, go to this Texas Cooperative Extension website for Williamson County Home Horticulture. At the bottom of the webpage, you will find phone, fax and e-mail information for reaching their office. If the problem you are having is showing up in other gardens in your area, the Extension Office may have some literature or advice on how to handle it.

Vitis mustangensis

Vitis monticola