This month we present a repeat of a past column because the topic is so timely. In June 2010 I was shown a rose bush with “witch’s broom” sprouts. This is a sign of a deadly wind-borne virus that can wipe out every rose bush in the region. Now another instance has popped up in our neighborhood and others within a few miles. Please see below for what to look for and what to do. The photo above shows the telltale twisted foliage, on the lower sprig.
Dear Miss Floribunda,
Enclosed you will find a sprig from my favorite shrub rose. It is weird looking, with twisted leaves and sprouts whirling out of other sprouts. Last year the same thing happened but it flowered. Nonetheless, I think something is the matter. Could this be a result of it being planted too close to a white hawthorn? I really love both of them and don’t want to lose either. What do you think?
[street name withheld]
I too was perplexed, having never seen anything even remotely like this except a condition called “witch’s broom” that sometimes appears on trees. It seemed to require a disease expert, so I took it to my Cousin Moribunda.
She took one look, and said, “This is serious. This is rose rosette disease, blown in from the west. It’s deadly and it’s contagious. Tell her to leave the hawthorn alone but dig up the rose bush and burn it. If the city doesn’t allow that, she should bag it and throw it in the trash.”
A rose-lover myself, I asked if there weren’t some way to cut back the diseased part and save the bush, but Moribunda told me not to be sentimental: “Remember those old movies, Old Yeller and The Yearling? Like them, this plant has become dangerous and it’s got to go!”
Next I took it to my friend in the American Rose Society, Citizen Cane, and then to an expert at the National Arboretum, Racine Greenfrond. They agreed with Moribunda, but gave me more information.
Rose Rosette Disease (RRD) is a virus carried by a microscopic wingless mite (eriophyte). It was introduced into the western United States by the USDA in the 1930s to control invasive multiflora roses, but because it’s wind-borne it came east with tornadoes. It was not supposed to affect any other rose, but obviously it has ─ sometimes in epidemic proportions.
The experts confirm that your rose bush will not live more than a few more years, though it will flower. The mite carries a vector that, once established, is fatal. The fact that it lingers makes it a menace to every rose bush in your neighborhood, so speedy removal is imperative. Once you dig up the diseased rose bush, carefully removing any pieces of root, you must not plant another rose in its place for two years.
Citizen Cane regrets to say there is no organic control, and the only miticide that works is Avid. Avid is for prevention only ─ there is no cure. He urges you to spray all your other roses with Avid. I’m sincerely sorry, but Moribunda is right. I am withholding the name of your street so rose growers won’t come looking for you with torches and pitchforks.
The Hyattsville Horticultural Society will next meet at 10 a.m. on July 21 at the home of Jeff and Marsha Moulton, 6122 42nd Avenue.