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Hollyhock trouble: weird spots/bumps

Posted by sahoyaref Alberta z3a (My Page) on
Mon, Jul 11, 05 at 19:40

Visited my mom yesterday, and her perennial garden (that I mostly planted and designed) is doing well, except for this large white hollyhock. My mom bought it from a neighbourhood lady who has a perennial sale every year. I believe it's a two year old division, and it gets white flowers. It grew very large this year, and it just coming into bloom, but the large leaves are COVERED in these strange spots. From the top of the leaf, they look yellow, but if you look under the leaf, you see that they are actually white bumps with a brown 'head'. A little like pimples, if you will, and just as gross-looking. The bottom leaves have actually been almost completely eaten away, with only the leaf viens remaining. It is extremely unsightly, though the plant appears to be in otherwise good health. It has not spread to the surrounding plants at all. I know that there is something that Hollyhocks are prone to, but I can't remember if this is it or not. What are they? Fungus? Bug eggs? And how can I get rid of them in an environmentally friendly way? (No strong chemicals). If this will be a never-ending battle, please let me know, so that we can just grow something else in that spot.

Follow-Up Postings:

RE: Hollyhock trouble: weird spots/bumps

Could be hollyhock rust? (which won't spread to other plants - it's something inherent to hollyhock leaves) Raised fungal bumps on the back of the hollyhock leaves are a typical sign of hollyhock rust - my neighbours hollyhocks were infected this way and she simply removed the affected leaves and enjoyed her hollyhocks on leafless tall stocks - not sure if she composted those leaves as that might contribute to re-infestation?

RE: Hollyhock trouble: weird spots/bumps

You are right to question whether or not to compost. Throw it in regular or city compost garbage if you do cold composting. I do hot composting and baby the piles to 60C so any rust is killed as well as weed seeds. So unless you are doing this, throw them out.
I have had a hard time growing these beauties, but am finally winning the battle. Mine are now growing in compost amended soil which is also mulched with compost. The soil is rich but this has been a three year process. I also add corn meal to the soil in and around the HH. This invites good nematodes and combats such things as HH rust.
Three years ago, I had to take all my plants out - they were dying of the rust. Coudn't even let them bloom. They were really bad. Last year a couple came up quite nice. This year (cross your fingers) they are all doing nicely.

The disease affects HH doubles the worse. The single fig-leaf HH can be affected but most times are not. And then the other native mallows such as the Marshmallow plant (Alcea ?) is not affected at all. Having grown all of these, this line of thought has proven to be very true in our gardens.

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