Battling Hollyhock Rust!


“The last few years my hollyhocks get yellow spots on the leaves. They are mustard colored. What is causing it?

V Clarkin”

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Hi V,

Thanks for your question regarding your hollyhocks. Sounds like you have Hollyhock Rust!

Hollyhock Rust

Hollyhock Rust often occurs on the underside of the leaves and looks like someone peppered the plants with dry mustard.  As the fungal rust develops, the upper side of the leaf will have beige to yellow blotches on it.  If left untreated, the entire plant will become infected, with the leaves dropping, the stem becoming spongy, and the plant eventually dying.

If you believe in using chemicals to control disease, you can douse the plants in an all-purpose systemic action fungicide every two weeks from early spring through the end of the season.  Keep in mind that these types of fungicides will affect the pollen and nectar of the plant and poison bees that visit the flowers.

If you wish to treat it organically, you should remove the leaves as soon as they become infected.  When late fall/winter comes and the plant has died back, remove all debris from the plant — if left behind, it will infect your plants next year.  If you have other Mallow family members in your garden (Hibiscus, Marshmallow, Lavatera, Common Mallow, and Mallow family weeds), remove the plant debris from these too as they will also harbor the fungal spores through winter.  Put this debris in a garbage bag and send it to the dump or burn it.

I hope this information helps you out. If you have any other questions, please feel free to ask.

 

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One thought on “Battling Hollyhock Rust!

  1. I know a lot of people say that bees are not killed by systemics, but it is true. I used to work at a farm that grew pumpkins and squashes that were treated with systemics throughout the seasons. The bees would start to come in as soon as the plants began to flower and would be dead soon after. The guy I worked for said it was just that they were old bees. I guess only old bees visited the patch. If the bees die from it, you know it is in the squash and pumpkins too. These days so many people have cancer, autism, etc. Makes you wonder if some of it is due to the pesticides that are on our food or inside it from the growing process. I will be following the organic method you mentioned. First was worried that you were going to tell me to spray them but then was glad to read further and see the organic method. Thank you for answering the question. I really like your blog and always find good articles on it so thought it’d be great to see if you could help me out too. Thanks for your help and hope you have a good 2014 gardening year.

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