Native Plants

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Friday - June 27, 2008

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Pruning, Shrubs
Title: What about the brown dots on my Silver sage?
Answered by: Jimmy Mills

QUESTION:

During the past year, the leaves on my silver sage bushes around the perimeter of the front of my house have turned yellow in places and there are tiny brown dots on virtually all of the leaves. If I shake the bushes, the leaves easily fall off. They haven't flowered in ages and look incredibly sickly. What can I do to save them? Part of one has already died and I trimmed it off, but this has spread to all my sage which are 8 years old. Everyone keeps telling me they are disease resistant, but there is something definitely wrong with them. Please help! Jody in Shady Hollow

ANSWER:

When I look for Silver Sage in our Plant Database I am referred to two species of Artemisia, A. cana, and A. filifolia, neither of which are usually used as landscape plants in this area. I'm guessing that you have Cenizo (Leucophyllum frutescens (Texas barometer bush) which is also called Texas Silver Leaf and Texas Sage, and is seen in yards throughout Austin.

Cenizo is generally described as being resistant to fungal diseases and tolerant of drought conditons, but this can be altered by environmental stress. Three important environmental factors that effect plants are light, water, and mineral nutrition. Since you say the plants have been growing for eight years, and presumably flowering, one approach is to look at what has changed in the past year. Has the amount of sunlight they receive been changed by encroachment of other shrubs or trees? Are they receiving too much water from your lawn sprinklers? What about fertilizer? The fertilizer that you might use on your lawn probably has a nitrogen: phosphorus ratio that is too high to promote flowering in Cenizo. Are they having to compete with other plants for nutrients? Getting back to the growth conditions of previous years may help your problems.

The brown dot could be one of the fungal leaf spot diseases which are inherently difficult to diagnose via email. I am going to refer you to the Travis County Extension Service's sick plants web site for advice with that problem.

From the Image Gallery

Cenizo
Leucophyllum frutescens