Rose Rosette

Johnson County Master Gardeners prepare a rose garden at Cleburne’s Hill College. A multi-year study is underway at the college to determine causes and preventions for Rose Rosette.



One threatens ash trees, the other rose bushes, Johnson County Agrilife Extension Agent Justin Hale said. Both warrant concern and monitoring though Johnson County appears safe from the first threat for the time being.

Such may not be the case in neighboring Tarrant County where an entomologist last week may possibly have  identified an emerald ash borer.

The emerald ash borer is a destructive, non-native, wood-boring pest of ash trees,” according to a Monday release from the Texas A&M Forest Service. 

The beetle was first discovered in North America in 2002 in Michigan and first detected in Texas — Harrison County to be exact — in 2016.

The beetles, which have spread to over half the 50 states, kill ash trees within two to five years of infestation, according to the release.

A photo submitted by a 10-year-old naturalist last week is believed to be an emerald ash borer, Texas A&M Forest Service officials said confirmation requires additional investigation.

“Since positive identification of an emerald ash borer cannot be confirmed by a photograph alone, the current investigation in Tarrant County is to locate an adult or larval specimen of the insect, according to the release.

Hale on Wednesday said he’s aware of the possibility of the emerald ash borer’s presence in Tarrant County and efforts ongoing to confirm or deny such suspicions.

“I know about it and I’ve heard talk about it,” Hale said. “At this point I’ve heard no reports of them being in Johnson County. It’s something we’ll continue to pay attention to though especially if it’s confirmed that they’re in Tarrant County.”

Johnson County Master Gardner Ben Oefinger said he’s heard of the troublesome beetle as well but knows of no reports of it in the area.

“I don’t have ash trees,” Oefinger said. “They’re not really recommended for this area and not that common around here. In fact, I couldn’t tell you of a single one in Cleburne. Of course, now that I’ve said that I’m sure a bunch of people will call to tell me they have them.”

More troubling for now and definitely here is Rose Rosette, Hale and Oefinger said.

“It’s been around a while and caused significant damage to the rose industry,” Hale said.

Fellow Johnson County Master Gardner Gary Wylie agrees.

“It’s a virus spread by mites that’s just been devastating to roses,” Wylie said. “They had to pull thousands of rose bushes out of the Fort Worth Botanic Garden and destroy them and we’ve seen it in Johnson County too. The disease is not curable at this time and they have not so far found any variety of rose that is resistant to it.

“It doesn’t seem to affect other flowers. But the rose is, of course, our national flower and like I said this has just had a devastating effect.”

The eriophyid mite, a microscopic insect, spreads the disease from rose bush to rose bush, Wylie said.

Rose Rosette was first detected in 1940 in Canada and the following year in America when it showed up in California and Wyoming. 

It was first detected in Fort Worth in 1998 and has since been detected in Johnson County.

“It started in Multifloria rootstock,” Wylie said. “Which you used to see planted along roadways to stop erosion problems. But it’s since spread to all varieties of roses.”

The disease alters the growing habits of rose bushes, Wylie said.

“There are real good indicators of the rose rosette virus,” Wylie said. “ All the sudden you’ll have a shoot come way up abnormal growth. Taller the normal rose bush. It will be red like all new growth. Secondly, on top of new growth especially the leaves will start to turn in and form what’s called a witch’s broom. They turn real gnarly and turn into each other and form a big ball top. And third, on a normal rose bush if you have stem will have 15, 16 thorns. If it’s infected with rose rosette you’re going to have hundreds of thorns in that same amount of space.

Much remains unknown about the disease, Wylie said.

“They have not decided if spread by pruning or to my knowledge by roots touching each other or the soil or anything like that,” Wylie said. “They did recommend, if you have an infected that you carefully remove and bag that rose and some of the soil too and burn it.”

Eriophyid mites may also be present but harmless, Wylie said.

“Not all the mites carry the disease,” Wylie said. 

Thousands of scientists across the country and several universities continue studying the problem in search of solutions.

Texas A&M University received a grant for such purposes part of which they used to establish a rose garden at Hill College’s Cleburne campus.

Wylie and other master gardeners in addition to Hill College students have monitored the rose garden for a little over a year now. 

“Our first confirmed case of Rose Rosette in Johnson County was Oct. 13, 2016,” Wylie said. “The Hill College rose garden, which has 20 varieties of rose bushes, went in April 21, 2017, as part of a two-year study.

“As of last week the rose bushes have not shown any signs of Rose Rosette and appear to be healthy. But we’ve seen it in other rose bushes in the county, know how much damage this has caused the rose industry and we’re a lot of us are working together hoping to find some answers on how to prevent or cure this stuff.”

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