Garden Q&A: Rust can take away from your hollyhock's beauty
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 www.jessicawalliser.com.
Send your gardening or landscaping questions to email@example.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- Penguins trade for Toronto’s Kessel
- Pirates notebook: Cole cool about hostile comment
- Saudi prince will donate all wealth, $32B worth
- Ligonier Township officer’s widow to file civil suit
- Three seek to serve four-year term in seat of deceased county council member
- Steelers submit application to host Super Bowl
- Leading on race: Communities, not elites
- Second Blair County friar commits suicide in province under sex abuse investigation
- Famine nears in Yemen; deadly blasts continue
- Donora-Webster Bridge plunges into Mon River after 106 years
- FBI searching for Homestead man indicted for sex trafficking in children