En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Black Sooty Mold on Bay Tree

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

Monday - February 25, 2013

From: Plum, TX
Region: Southwest
Topic: Non-Natives, Diseases and Disorders
Title: Black Sooty Mold on Bay Tree
Answered by: Anne Van Nest

QUESTION:

I have a large bay tree and all the leaves are covered with a black mold-like substance on the top part of the leaf. Under each leaf are some black/brown spots. I have washed the leaves with soap and water using a wash cloth. This cleans the leaves some but this stuff is stubborn. I really do not want to hand wash 1000+ leaves. I have tried fungus sprays, mold spray, and high pressure washing with just water. Nothing seems to help. All the new growth is getting the same gunk. Help!

ANSWER:

Sorry, bay laurel trees (Laurus nobilis) are a little out of our line since they are native to the Mediterranean. The Lady Bird Johnson Wildflower Center, home of Mr. Smarty Plants, is committed to the growth, protection and propagation of plants native not only to North America but to the area in which they are being grown. In Texas, this is Texas A&M. Below though are links to several websites which we believe have the information you are looking for. Look at the Texas A&M AgriLIFE Extension web page on bay laurels.

Your plant symptoms though are similar to what sooty mold does when it attacks some native plants. The sooty mold grows on the honeydew that is excreted by small soft-bodied aphids or scales that suck sap from plants. In your case there is a laurel aphid that attacks bay laurel trees and excretes a sticky, sugary substance that drips down onto the tops of lower leaves. Soon thereafter, a black, mold grows on the sugar. The sooty mold blocks the light to the leaf and weakens the plant.

Look for small pale green insects (aphids) on the new growth or small round bumps (scale) to find the ultimate culprit of the problem.  Once you have determined the honeydew cause (and solved this problem), you will be able to get your mold under control. For more information look at this ehow article on bay laurel tree problems.

 

More Non-Natives Questions

Invasive plants in native plant area from Austin
May 15, 2012 - Why do invasive plants grow in native plant territory?
view the full question and answer

Competition between Horseherb and Chickweed
July 04, 2014 - Ok, sorry I did it wrong the 1st time!? I live in Houston, and I have chickens! I also have mass amounts of Horseherb, and I want to buy some chickweed seeds and plant it for my chickens! My question ...
view the full question and answer

What about Asian Jasmine and scrub oaks?
September 01, 2010 - Dear Mr. Smarty Plants, I have several clusters of native scrub oaks in my yard. I planted Asian jasmine under them many years ago. The trees look fine, but an arborist has told me that the Asian ...
view the full question and answer

Controlling pumpkin vine in British Columbia
July 15, 2008 - I have never grown pumpkins before but decided to try one plant this year. It seems to be taking over my small garden space. Can I prune it back? I only want one or two pumpkins for my grandchildre...
view the full question and answer

Brown spots in St. Augustine grass
July 05, 2008 - Mr. Smarty Plants, My husband and I are in the Air Force and were recently moved to Cibolo Texas. We built a home and hired a landscaper to finish the yard May 07 (with irrigation system). We laid d...
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