| Lifestyles

Larger text Larger text Smaller text Smaller text | Order Photo Reprints

Garden Q&A: Rust can take away from your hollyhock's beauty

- If you look at the upturned leaf between two of the flowers on this old-fashioned hollyhock, you'll see signs of a rust infection -- orange pustules. Jessica Walliser
If you look at the upturned leaf between two of the flowers on this old-fashioned hollyhock, you'll see signs of a rust infection -- orange pustules.  Jessica Walliser

Email Newsletters

Sign up for one of our email newsletters.
Related .pdfs
Can't view the attachment? Then download the latest version of the free, Adobe Acrobat reader here:

Get Adobe Reader

Daily Photo Galleries

Friday, Jan. 4, 2013

Question: My old-fashioned hollyhocks were a complete disaster this year. By old-fashioned, I don't mean those new-age carnation types; I mean those single-petaled types we had as kids. This past spring, the leaves developed normally, but then a brown, ugly fungus took over. The stalks grew tall, but there were only puny buds and no flowers. Then the leaves and stalks died. What caused the fungus? What should I do in the spring to avoid this problem again?

Answer: Rust is a common fungal disease among hollyhocks, and the symptoms you describe are classic. There are thousands of different species of rust, some of which are major agricultural pests. The species of rust that attacks hollyhocks is Puccinia malvacearum and, unlike some other rusts, it needs only a member of the hollyhock family to complete its lifecycle. Other susceptible plants include mallows, rose-of-Sharon, lavatera, and flowering maples ( Abutilon sp.). The good news is that rust seldom kills hollyhock plants, but it does, as you discovered, make them look terrible. Here's what to do about it for next year.

The spores of hollyhock rust are spread from plant to plant primarily on the wind, though they can be spread by humans, animals or insects. Initial signs of rust are small, pale splotches on the upper leaf surface. They quickly turn into brilliant orange bumps on the lower leaf surface. These are the spore-producing bodies. They can also occur on the stems and even flower buds. In severe cases, as you discovered, affected leaves often shrivel up and drop off the plant entirely and the flowering is reduced.

As with all fungal diseases, wet leaf surfaces promote infection. Be sure to give your hollyhocks plenty of room to optimize air circulation around the plants. Always irrigate the root zone only and avoid wetting the leaves whenever possible. Since the spores easily survive winter on infected leaves and stems, right now you should head out to the garden and remove every piece of old foliage and all the stalks. Dispose of them in the trash or burn them. During the growing season, remove and throw away infected leaves as soon as possible.

You also can use an organic biofungicide such as Serenade to aid in the prevention of rust next spring. It must be applied at 10-day intervals to upper and lower leaf surfaces before the initial signs of infection occur.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212

Subscribe today! Click here for our subscription offers.



Show commenting policy

Most-Read Stories

  1. Steelers notebook: Tomlin not grooming successor to RB Williams
  2. 11 more artist-designed bike racks from Cultural Trust line Pittsburgh streets
  3. Penn State coach Franklin calls for patience
  4. Christmas comes to Westmoreland County in many ways
  5. McIntyre students hope Buddy Bench is beneficial to all
  6. ISIS claims hotel attack in Egypt
  7. North Hills businessman’s secretary pleads guilty, says she helped him hide $27M from IRS
  8. Obama pledges support for France against ISIS, wary of role for Russia
  9. Thanksgiving by the numbers
  10. House Republicans call for refugee limits in spending bill
  11. Bowl destination is at stake for Pitt football in regular-season finale