En EspaŅol

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.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

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
2 ratings

Friday - June 22, 2007

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Saprophytic fungus on mulch
Answered by: Joe Marcus


I just did some major landscaping in my west Austin, TX backyard. I added many native plants and mulched all of the new beds. I did this just before the heavy rains in the past two weeks. I now notice a powdery white substance in the mulch (not on the plants). Is this powdery mildew? Whatever it is, do you have any suggestions regarding what to do about it? Thank you.


Chances are the white powdery substance you describe is a saprophytic fungus growing on the mulch. Saprophytic fungi are those that live strictly on decaying organic matter. Most such fungi are incapable of doing harm to plants. It is very common to see blooms of fungal growth on shredded bark and other mulches after rainy spells.

More Diseases and Disorders Questions

Red-backed bugs on mountain laurel (Sophoro secundiflora)
May 12, 2010 - I found red-backed bugs (in fact two end-to-end like the east Texas love bugs) on my mountain laurel which has been losing leaves. Are these bugs the culprit?
view the full question and answer

Advisability of trimming oak trees in August
July 13, 2007 - In general,what is your opinion on pruning oak trees in August? If it is positive, should the extreme moisture of this year affect the timing?
view the full question and answer

October 19, 2015 - A couple of weeks ago the leaves on my decade old cherry laurel began to turn brown. Now they are entirely brown. I have not changed the way in which I cared for it, but about three days ago I noticed...
view the full question and answer

Gaura Plants Dying In PA
July 16, 2014 - I had six gaura plants. They were beautiful last year. Now I have one that is doing well and the others are dying slowly one at a time. I don't understand this. They are on a slight slope and have ...
view the full question and answer

Damage to native elm in Texas
August 20, 2008 - We had a major landscape renovation done over the winter. One of the trees, an elm about 10 yrs old, remained in the bed although plants around it were removed. The tree has suddenly started turning...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center