Host an Event Volunteer Join Tickets

Support the plant database you love!

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

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

Monday - March 28, 2005

From: SF, CA
Region: California
Topic: Diseases and Disorders
Title: Pustules on geranium
Answered by: Joe Marcus

QUESTION:

I have a geranium that has developed oblong red/brown pustules/raised bumps on the undersides of the lower leaves. The foliage around the bumps is stil green but everything else has yellowed

ANSWER:

Thank you for writing! The problem you describe sounds like oedema (sometimes spelled: edema; pronounced: ed-ee'-ma). Oedema is not a disease, but a physiological disorder. It is a problem with many plants, but is an absolute disaster for geraniums (Pelargonium X hortorum) -- especially ivy geraniums (P. peltatum). Native geraniums are not as affected by the condition. Oedema is a result of ruptured cells, usually on the underside of a leaf, caused by a complex of issues involving water availability, humidity, temperature, air movement, and plant nutrient levels. In severe cases, the plant will drop the injured foliage, sometimes denuding the plant. The University of Georgia Cooperative Extension website has a nice article on Geranium Diseases including a section on oedema.
 

More Diseases and Disorders Questions

Non-fruiting squash
July 25, 2007 - With all this rain in Dallas why would our Zuchinni and Yellow squash be beautiful and green but not produce any squash?
view the full question and answer

Grubworms in Austin Flower Bed
March 09, 2011 - How do I get rid of grubworms in my flower beds?
view the full question and answer

Native Grass is Falling Over
November 09, 2011 - Hi Mr. Smarty Plants, I've tried to find this answer but am stumped as to the cause. We live in Fredericksburg, TX and have several different tall grasses, Yellow Indian grass, Little Bluestem, wire...
view the full question and answer

Oak bark problems from Stillwater OK
May 14, 2012 - In my clients large oak tree there is bark stripped from the limbs in small pieces. No piece is larger than 1 inch by 1 inch and occurs on limbs high in the canopy. It does not look like squirrel doin...
view the full question and answer

Small oak tree with powdery mildew in San Antonio, TX.
May 09, 2012 - I have a small oak tree with powdery mildew. Is there anything I can do about? Will it kill the tree?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.