Native Plants

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer

Not Yet Rated

Tuesday - May 26, 2009

From: Philadelphia, PA
Region: Mid-Atlantic
Topic: Diseases and Disorders
Title: Problems with Blackeyed Susans in Philadelphia
Answered by: Barbara Medford

QUESTION:

For 8 years I successfully grew Black Eyed Susans in a fairly large area in my garden. For the last two years,almost immediately upon pushing through the ground they develop black spots and then appear to be eaten away. They continue to grow but the blooms are not vivid and the leaves are ugly. I have tried a variety of bug sprays - 3 in one,and copper dust. I just recently sprayed with Bayer Advanced-Insect control (3-in 1). I plan to spray weekly. Will that work?

ANSWER:

First, stop spraying pesticides. They are contaminating the soil and the air, and killing beneficial insects. Without knowing what the problem is, you can't hope to cure it with pesticides. Have you actually seen any insects? This sounds more like a soil problem, if they are showing symptoms as soon as they come up. Another strong possibility is mold. Although a number of different plants sometimes carry the common name "blackeyed susan," Rudbeckia hirta var. pulcherrima (blackeyed Susan) is native to Pennsylvania. It is a biennial, which will continue to reseed itself if it is in good conditions. It requires full sun, which we consider to be 6 hours or more a day of sun, and dry sandy soil. If conditions have changed in your garden, some other plants may be shading your flowers. You need to always clean up the debris in the garden on a regular basis, to help prevent mold or over-wintering insects from thrivng. Over-mulching, over-watering, over-shading, over-crowding all could be causing this problem.

Read this Purdue University website on Septoria Leaf Spot of Rudbeckia.

University of Florida Cooperative Extension Service Rudbeckia hirta names several diseases and insects that may be causing the problem.

You can't treat a disease without knowing what it is. Your spraying is very likely not only not helping, but may be encouraging the decline of your plants.

Rudbeckia hirta var. pulcherrima