June 25, 2014

Bad News for Princeton’s Rose Lovers, Rose Rosette is Here and Spreading

O ROSE THOU ART SICK: William Blake may not have meant his words to be taken so literally, but it’s hard to avoid his line when looking at these before and after images. Eriophyid mites, although tiny, can cause dramatic plant deformities such as the “witches broom” shown here.(Photograph by L. Arntzenius)

O ROSE THOU ART SICK: William Blake may not have meant his words to be taken so literally, but it’s hard to avoid his line when looking at these before and after images. Eriophyid mites, although tiny, can cause dramatic plant deformities such as the “witches broom” shown here. (Photograph by L. Arntzenius)

Princeton’s rose growers are struggling to come to terms with Rose Rosette Disease (RRD) a very nasty infection that is spreading through the region’s rose bushes. If you haven’t seen much about it in print, that might be because those affected are in denial when it comes to the possible demise of their beloved rosebushes.

“It’s a viral disease transferred from plant to plant by an eriophyid mite and there’s nothing you can do about it,” said horticulturist Barbara Bromley of the Cooperative Extension of Mercer County at Rutgers, the State University of New Jersey.

Ms. Bromley was responding to a call Monday about the sickness that has affected a fragrant floribunda in this reporter’s garden.

“Almost anyone who grows roses in Princeton will have this” she said, adding that she has responded to numerous calls from locals about destroyed leaves and blooms on prized ornamentals. “I’ve even seen this disease on Knockout roses too,” she said referencing the popular rose variety that is a favorite of garden supply sections in big box stores.

I first noticed the problem when a beautiful peachy-colored rose that has bloomed all summer long since it was planted some six years ago began showing foliage that was twisted in on itself. The leaves were reddish in color and the roses that ultimately formed were clearly not normal. When I described the growth to a fellow gardener, her immediate response was: “witches broom.” That did not sound good.

That was two summers ago. Last year, it got worse; this year, in spite of hopes that the recent hard winter might somehow have ameliorated its spread, there are even more signs. There is no magic bullet when it comes to dealing with RRD.

Known widely for her gardening advice through the Master Gardeners of Mercer County program, Ms. Bromley advised drastic action. Remove the entire plant including every bit of root. Although the virus will not be in the soil, she also advised resisting the temptation to replace the diseased rose with a healthy one. “If you got it once in that spot, chances are you will get it again,” she said. “And, ‘witches broom’ is a symptom of the disease rather than a name for the disease itself,” she clarified.

If you have wild multiflora roses nearby, you should do your best to get rid of them, she told me. But the best way to avoid problems such as this is, “not to plant too many of any one plant.”

Ms. Bromley explained that the airborne infected mites inject the RRD virus into the rose as they feed. Non-infected mites can pick up the disease from an infected rose and spread it to another plant courtesy of a gust of wind.

One Gardener’s Experience

It took a week for local rose cultivator Liz Hosny to discover that one of her roses had RRD. She sent a photograph to the well known Philadelphia gardener Judy Perry who identified the problem immediately. “This rose was in its own bed but three others elsewhere were showing signs of it; I pulled them out and carefully removed every piece of root,” said Ms. Hosny, who lives on the border between Princeton and Lawrenceville, where she has about 100 rose bushes in her garden including a bank of David Austen’s that are not grafted.

“Now I am feeding my roses with lots of natural feed like seaweed,” said the avid rose-grower, who is modeling her method of dealing with the virus on the survival history of former basketball player Magic Johnson. If the athlete can stave off full blown AIDS by maintaining a healthy lifestyle, perhaps, reasons Ms. Hosny, her roses will survive if she keeps them fit and healthy too.

In spite of the disease she is not taking out any of them until she absolutely has to, but she is on constant alert. “If I see any deformed branches, I remove them immediately,” she said.

“So far so good,” she said. Ms. Hosny has developed a philosophical attitude to gardening over many years. “If you are a gardener, you can’t always do what you want to do, sometimes you have to do what the land will allow you to do. If I have to live without roses, so be it,” she said.

Numerous online sources offer advice on RRD. One garden blogger, Ann Peck (see: www.rosegeek.com/index.htm), claims to have “cleaned” and saved a rose by cutting out and removing the infected parts. Ms. Peck is a member of the Asheville Blue Ridge Rose Society and a retired organic geochemist. Like Ms. Hosny, she suggests that removal of the infected parts might slow down the demise of an infected plant.

But beware of online misinformation, said Ms. Bromley. To be sure to get to a reliable source, she offers a handy trick: add the word “extension” to any search engine query. “That way you will get information from a university extension rather than from a chat room or from someone trying to sell you ‘a cure,’” she said. “There is no cure.”

As for substitutions for roses, Ms. Bromley suggests that if you want flowers, consider perennial plants instead.

If in doubt, Ms. Bromley suggests, gardeners should check with an expert like those in the County Extension system.

The Master Gardeners of Mercer County answers home horticulture questions through the helpline, (609) 989-6853, Monday through Friday, 9 a.m. to 3 p.m. (March through October) and 10 a.m. to 2 p.m. (November through February). For more information, visit www.mgofmc.org.