Native Plants

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Monday - September 22, 2014

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Why are my Rock Roses dying?
Answered by: Joe Marcus

QUESTION:

I planted several rock roses last fall. This spring they have grown wonderfully, but all of a sudden, one shriveled and died. I took it out and replaced it. Now, another is starting to shrivel. It starts in one branch, then spreads across the plant. The plants on either side are thriving. What is happening?

ANSWER:

Several unrelated plant species are known in various places as Rock Rose. Because of your location in Austin, TX, we're going to assume that you're are referring to Pavonia lasiopetala.

Except in very rare cases, it is not possible to positively diagnose most plant diseases and disorders sight unseen. We recommend contacting your county's AgriLife Extension Service office for details on submitting a plant sample for disease testing. However, if the cause of your plants' problems are not disease-related, the test will only be able to rule out a pathogenic cause.

Our first thought, though, is that the most likely malady besetting your Rock Roses is Cotton Root Rot. Cotton Root Rot -- caused by the fungus, Phymatotrichum omnivorum -- is probably most serious disease of ornamental plants in Texas.

Plant species susceptible to this disease should not be planted in soil that previously held Cotton Root Rot-infected plants as the pathogen remains in the soil and can infect new plants long after dead plants have been removed.

From the Image Gallery

Rock rose
Pavonia lasiopetala