Native Plants
![](../_images/smarty_plants.gif)
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.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
![](../_images/mr_smarty_plants_logo_web_200w.jpg)
rate this answer
![](../_images/star_43.gif)
Thursday - May 05, 2011
From: Round Rock, TX
Region: Southwest
Topic: Diseases and Disorders, Watering, Shrubs
Title: Powdery mildew hits Rock Rose in Round Rock Texas
Answered by: Lleslie Uppinghouse
QUESTION:
My beautiful Rock Roses have gotten spots of white fuzzy "fur" on their leaves in the past month. This is not something they have ever had before and I'm worried its some kind of disease. Is it something I should worry about and if so is there some way to treat it? I love my Rock Roses they are one of the few plants that survived Austin's two weeks of freezing temperatures this last winter. I dont want to lose them. I bought them from the LBJ Wildflower Center Spring plant sale two years ago. Sigh.ANSWER:
Powdery mildew is almost unavoidable with Pavonia lasiopetala (Rock rose). Many plants with woody stems and fuzzy leaves struggle with this nuisance. Powdery mildew is a common fungal infection. Hot sun helps reduce the chance of mildew forming so if your Rock Rose is not in the full sun you might want to think about moving it. Also it is important to make sure that this plant has good drainage. Although poor drainage isn't the cause of mildew, the combination of soggy roots with mildew can stress out the plant enough to kill it. Pavonia also likes to be cut back every year, keeping it from becoming leggy. Some theorize that if you do this twice a year rather than once, it helps keep the mildew away.
We are suspecting that it is the cloudy days combined with early hot temperatures that is exacerbating the situation. Once mildew develops you may find that it returns again and again, even in the hot sun of summer.
The good news is that powdery mildew can be beat with household ingredients. Use one half tablespoon of baking soda and a couple of drops of dishwashing soap (something natural if you can) mix it up with one half gallon of water in a spray bottle and spray the leaves. This changes the PH on the leaves slightly making it tough for mildew to form and spread. You might have to do this every now and then to keep the mildew away. Other than being susceptible to powdery mildew, Rock Rose is a tough little plant. Well, worth fighting for.
From the Image Gallery
More Shrubs Questions
Evergreen shrubs for urns at entryway in Midland, Texas
November 16, 2009 - I am looking for plants for large urns at my entry .. prefer something evergreen. The urns are about 3' tall with an opening of 10-12" .. also prefer a plant that is not too bushy or whose roots wi...
view the full question and answer
Native trees and shrubs for Austin
June 11, 2008 - Hello,
I'm searching for a small or medium-sized endemic or native tree (or tree-like shrub) to feature in the front yard of my South Austin bungalow. I want something that provides dappled shade so...
view the full question and answer
Transplanting and germination of Pride of Barbados in Adkins, TX
April 02, 2012 - What is the root system like of the Pride of Barbados? I have a lot of new plants coming up in my beds from seeds. Can these be transplanted to a new location easily without damaging the plants? If...
view the full question and answer
Propagation of possumhaw from Austin
May 22, 2014 - I planted a possumhaw holly plant about 3 months ago and am really excited to watch it grow from its current 3-foot height. It is starting to berry right now. My question is about those berries: (Cle...
view the full question and answer
Floristic Quality Assessment program in Texas?
January 19, 2009 - Do you have knowledge of a Floristic Quality Assessment program for Texas such as the ones used in Indiana and Illinois?
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |