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?

Share

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
Not Yet Rated

Wednesday - August 20, 2008

From: Mount Gilead, OH
Region: Mid-Atlantic
Topic: Diseases and Disorders
Title: Fungus type problem on native blackeyed susans in Ohio
Answered by: Barbara Medford

QUESTION:

I have black eyed susans that have recently developed a black fungus type problem in the bottom and on the leaves. The flowers are now wilting and dying. What is this and how can I stop it from possibly spreading to the rest of my summer garden?

ANSWER:

The black stuff on your  Rudbeckia hirta (blackeyed Susan) is likely honeydew, excreted by aphids (most frequent culprit), whiteflies or mealy bugs. The honeydew is a sticky substance, usually on the underside of leaves. and it in turn becomes a host for sooty mold fungus. As with any fungus, the first line of defense is cultural. Don't use overhead watering on the plants. water early in the day so the leaves can dry out before sundown. Pick up and destroy infected leaves, both on the ground and on the plant. If the whole plant has been affected, even though the sooty mold will not probably kill it, you might consider destroying that whole plant to cut out one step in the infection of other plants.  Space your plants far enough apart for good air circulation, and make sure they are getting plenty of sun, both enemies of fungi.

Next, you want to get at the insects that cause the excretions. Don't use insecticides, because they will most likely kill the benign, natural predators of the insects, like ladybugs. Also, if your flowers are attracting butterflies or bees, you don't want to hurt them, either. This University of California Integrated Pest Management website Aphids covers some of the management practices for aphids, which will also apply to the other insects. A good hard spray of water (remember, early in the day) to the undersides of the leaves will usually dislodge the bugs and they won't be able to get back up.

One other possibility, somewhat more dire, is Verticillium Wilt. This University of Illinois explains that it is a soil-borne fungus, and there is no cure. If you determine that is the problem, we would suggest the immediate removal of the affected plant, especially since blackeyed Susans are usually annuals or biennials and easily replaced. And keep your eye out for any other plants exhibiting the same symptoms, removing them also.

 

From the Image Gallery


Clasping coneflower
Dracopis amplexicaulis

Black-eyed susan
Rudbeckia hirta

More Diseases and Disorders Questions

Sap oozing from non-native Chinese pistache in San Antonio
September 07, 2011 - I live in San Antonio, and my chinese pistache is exuding copious amounts of a sticky sap from old trim sites and from the trunk itself. The tree is about 12 years old and has been healthy up until no...
view the full question and answer

Care of Styphnolobium affine, Eves necklace
October 05, 2007 - I have an 18 yr old Eve's Necklace tree that is dying from the "bottom up". It has only a few leaves at the very top of the tree. I have, connected to the gutter, a rain barrel from which the exc...
view the full question and answer

Problems with Escarpment black cherry from Ponder TX
February 11, 2011 - I have an escarpment black cherry that is about three years old and about 9 feet tall. It was healthy until this last summer when its began to bark peel and sap run out at the base of the tree. The af...
view the full question and answer

Blackened leaves on purple sage in Utopia TX
December 08, 2010 - I live in Utopia Texas and have a 5-ft. Texas Purple Sage that has developed a black appearance on the leaves. What is this and what can I do about it?
view the full question and answer

Curling, Red Leaves on Gaura
July 18, 2013 - My gaura had most of its lower leaves turn red and then fall off. It is July now, I bought and planted it in May where it seemed to do really well growing several more inches tall and blooming nicely....
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 | STAFF
© 2015 Lady Bird Johnson Wildflower Center