En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Powdery mildew hits Rock Rose in Round Rock Texas

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.

Need help with plant identification, visit the plant identification page.
 
rate this answer
Not Yet Rated

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


Rock rose
Pavonia lasiopetala

Rock rose
Pavonia lasiopetala

More Shrubs Questions

Why are the leaves on my Laurel hedge turning brown in Everett, WA?
February 22, 2010 - Our laurel hedge seems to have brown leaves on the top of the bush. We haven't had a freezing winter so we are trying to figure out why some of the leaves are brown.
view the full question and answer

Need shrubs to plant alongside a swimming pool in Tampa, FL.
September 05, 2011 - I Have a 3 1/2 foot gap between my pool screen and back fence. This gap runs about 30 ft. long. I would like to place small trees to look beautiful and to grow 6-8 ft. high to screen out my neighbor...
view the full question and answer

Salt tolerant plants for Long Beach
May 12, 2013 - When Hurricane Sandy hit Long Beach, it has killed all my plants and now almost all of Long Beach is left with dead dried brown vegetation. I want to replant front with bushes and flowers. What woul...
view the full question and answer

Plants for a sunny, dry slope in NY
March 01, 2010 - Looking for plants, native to area, that are quick growing to a height of approximately 6" to 12" for a steep slope comprised of shale in a sunny location.
view the full question and answer

Young yaupon trunks bending in Houston
April 26, 2010 - I have new yaupon in this their second summer which are bending over about half-way up their trunk, at around two feet - do I trim them or stake them?
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center