Rose rosette virus is a disease that has become a prevalent threat to all ornamental roses in St. Louis.
History of Roses in St. Louis Landscapes
The knockout rose species has become a common flowering shrub in many St. Louis residential landscapes, and for good reason.
It’s a low maintenance, deer hardy, drought tolerant, black spot resistant species that the blooms throughout the whole summer.
As the most widely sold rose species in North America, it makes it easy for insects and disease to spread to mass groups of plantings.
How it spreads & what happens when roses become infected...
The Rose Rosette Virus is spread by a tiny (invisible to the naked eye), wingless mite that is often found on roses.
The mites feed on infected roses and are blown in the wind, transferring the pathogen, typically during the months of May through July.
Symptoms of Rose Rosette Virus may not appear for weeks after it’s been transmitted.
Viruses, like Rose Rosette Virus, enter cells and cause disease by replicating the cells and while they’re spreading the plants generally produce less chlorophyll and the hormones it needs for growth.
For the roses, this means stunted growth and odd growth patterns.
Identifying Rose Rosette Virus
Once infected, roses will display excessive, unexpected growth. Early symptoms include a red coloring on the underside of the leaf. Leaves will become brittle and deformed with yellow and red pigmentation.
As the disease progresses, the leaves get smaller, with intensely red shoots. Typically the Rose Rosette Virus will stunt the flowering of the plant and proliferation of thorns.
Towards the end of the life cycle for the rose, you can easily identify “witches brooms” on the ends of the canes which stemmed from explosive growth.
The disease causes the rose to be very susceptible to freeze damage, which we tend to see during early spring in St. Louis.
Early summer is the time that it is very easy to notice the disease at its infancy. Inspect your roses for symptoms as new growth appears.
Is there a cure?
Although the cause of the Rose Rosette Virus has been found, it has not led to finding a cure yet. Attempts to remove the infected canes when the disease is first sighted are often too late as the disease has spread into the roots. The use of pesticides and miticides are not practical or effective. There is no cure.
The good news is that the Rose Rosette Virus is host specific and only roses are susceptible to this disease. The bad news is that most rose species and cultivars are considered susceptible to this virus.
What are the solutions for Rose Rosette Virus in St. Louis?
Smaller roses will progress through the disease stages more quickly than larger plants. Small plants are usually destroyed in about 2 years, while a large plant may survive for five years in a deteriorated condition.
Dowco recommends removing the ornamental roses that show symptoms of Rose Rosette Virus. The entire plant should be removed including the roots.
There is some debate as to whether or not it is okay to plant another rose in the same spot. Some say the microscopic mite can still be in the soil and could strike again. At Dowco, we typically don’t bet on instant replay and when a species doesn’t thrive in a particular location, we try something else.
Arguably, an even bigger problem with installing another rose is the abundance of the Rose Rosette Disease in St. Louis and the lack of knowledge regarding it.
First, the disease can be spread by pruning. Dowco educates our pruning crews to sanitize their tools after each cut, but the majority of other companies do not take this care. Second, infested plants could be unknowingly purchased and introduced into the landscape, starting the process over again.
What can Dowco do?
Dowco can help you to identify the Rose Rosette Virus on your roses as well as come up with a plan to replace them. Other common, flowering shrubs that do well in St. Louis are Hydrangeas, Azaleas, Rhododendron, Crepe Myrtle, Peony, Spirea, Lilac, and more! Depending on your space, light and tolerance needs, there is a plant that will work for you!
