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Monday - November 09, 2009

From: Comfort, TX
Region: Southwest
Topic: Cacti and Succulents
Title: Problems with Agave americana in Comfort TX
Answered by: Barbara Medford

QUESTION:

We have lost a huge agave americana and are not able to find out what to do for our others. The one we lost was rotted or eaten (beetles?) at the base and the whole thing just fell over. We have a lot of very big ones and don't want to lose any more. Is there some treatment we should use? We cannot find any information or help with this.

ANSWER:

Agave americana (American century plant) is a tough desert plant; ordinarily information on it contains the phrase "no pests or diseases of any major concern." However, a little more research found several things that could be causing your problem.

Fungal lesions on agave are caused by soil-borne pathogens, including the fungus Fusarium, which can cause root and crown rot. A bacteria called colletotriachum causes anthracnose in the agave. It tends to occur in moist conditions, when the agave is in too much shade or is being irrigated from overhead. This is usually in concert with infestation by agave snout weevils. The agave snout weevil feeding on the agave enables these pathogens to enter. Once the microbes have entered the plant, there is no reliable control for the bacterial and fungal infections. From Centralarizonacactus.org Treating Agaves to Prevent Agave Snout Weevil Infestation by Tom Gatz, you can get more information on these problems.

For future problems, first avoid overhead watering, or just overwatering. If there is rainfall, you don't need to water agaves. During a dry period, watering them once a month suffices. Agave needs very good drainage. If water from irrigation or rainfall is puddling around the base of the agave, that will surely cause the fungal problems to be worse. Do not try to use transplants of "pups" from the affected agave, as they may already have the infection in their system. When a plant starts to show symptoms of these problems, remove it quickly to prevent spreading the disease to other plants. Located in Kendall County as you are, you shouldn't have that much trouble with damp, but apparently you have been. This is really one of those situation in which prevention is the only way to avoid losing more plants. See this article from HGTV.com on Agave meltdown.

From Google, images of Agave americana (American century plant)