Native Plants

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Friday - January 14, 2011

From: Spring Branch, TX
Region: Southwest
Topic: Cacti and Succulents
Title: Lesions on Agave Leaves in Spring Branch, Texas
Answered by: Mike Tomme

QUESTION:

I have a giant Agave americana that was beautiful until recently. Several of the leaves have lesions, some of them quite drastic, on the last third of the leaf. What is causing this?

ANSWER:

Boy, am I glad you only asked what the problem is rather than what to do about it, because that would have been a really hard question.

Agave americana (American century plant) is normally resistant to most diseases, but this previous Mr. Smarty Plants answer gives some information on the anthracnose fungus which seems to be the most likely culprit in your situation. This fungus thrives in wet conditions which, I suspect, has been the situation where you live over the last year. Shade can also contribute to the problem.

Ok, what to do about it (hard questions don't scare Mr. Smarty Plants). Here is an article from the University of Arizona that (briefly) discusses the issue on page 7. This article, which was also cited in the previous Mr. Smarty Plants answer mentioned above, recommends removal of the affected foliage and also mentions a fungicide that can be used if that is your preference.