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Wednesday - April 16, 2008

From: Georgetown, TX
Region: Southwest
Topic: Non-Natives
Title: Disease on non-native French hollyhocks
Answered by:

QUESTION:

I live in Georgetown, Texas. I have some French hollyhocks that have some kind of disease on the leaves - I would like to know what to spray them with to get rid of it. It looks like brown blemishes all over the leaf and the blemishes are small and round. It really looks gross. One of our local nurseries said it might be a bacteria of some kind but they weren't that helpful. I pulled off the infected leaves and the new growth eventually got the same thing. Please help! The plants have been hearty and a dark green until about a month ago.

ANSWER:

The French hollyhock is a lovely old garden flower; in fact, legend has it that Thomas Jefferson grew it at Monticello. That does not mean, however, that it is native to North America, indeed, it is native to Europe, north to Scandinavia and east to Russia and the Caucasus. The Lady Bird Johnson Wildflower Center is dedicated to the care and propagation of plants native to North America, so this is a little out of our field of expertise. However, we are always glad to help out, if we can, with problems gardeners are having with their plants. We hunted around for information on Malva sylvestris, French hollyhock, and mostly found that it had no serious insect or disease problems, although Japanes beetles can be a problem, where present. We did find one reference with said that the Malva sylvestris can be prone to rust fungus. Not having a clue what that was, we searched some more and found this website on rust fungus that is probably going to tell you more than you ever wanted to know, but there are a lot of pictures you can compare to the blemishes on your flowers. If you feel that is the problem, ask your nursery to recommend a good fungicide, and apply it exactly as instructed. Good luck!

 

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