Rose Rosette is a fungal disease that affects roses. Rose rosette is currently found in almost all parts of our country. As a professional in the field for more than 20 years, identifying rose rosette disease (RRD) has become easier, but is still easily overlooked by the untrained eye. Most recently, RRD has been spotted on Knock Out Roses. Action must be taken now in order to prevent the spread of RRD to all of the susceptible roses in our area.
In the past, RRD was thought to only threaten the native multiflora roses (Rosa multifora) that grow in the United States. It was expected to kill off the native Rosa multiflora, but this didn’t happen. Rosa multiflora still thrives on fencerows and tree lines in our area. In recent years, researchers and horticulturalists are noticing the susceptibility of the Knock Out Rose to Rose rosette disease. Now these native roses are considered to be hosts or carriers of RRD.
Rose rosette disease is spread in three ways and is a lethal disease for roses. RRD is spread by wind gusts, root to root spread, or a mite that carries the disease. Wind gusts easily carry RRD and spread it from plant to plant. There is also a mite that eats the foliage of the roses, travels to other roses, and spreads the disease through contact by doing so. Once the rose contracts the disease, there is nothing that can be done to save it, but there are some things that should be done to prevent the spread. Upon identification, the roses should be completely removed from the sight, placed in bags, and disposed of or burned. Every root should be removed from the ground and destroyed.
Identifying rose rosette disease can be difficult, unless you know which characteristics are sure signs of the disease. Rose rosette can be identified by irregular growth or deformed growth on a rose. Sometimes the cane coming from the plant will be thicker than the normal growth on the plant. Also, it will give what we call a ‘witches broom’ look where the new growth on the end of the stem grows in a very tight, congested manner. It will look completely different from the rest of the plant. Another key trait is smaller leaves or discolored leaves. At times, the color of the leaves will be the same as those on the new growth, but will stay that color for a longer period of time instead of hardening off to green.
In recent years the popularity of the Knock Out Rose has risen incrementally. It was believed to be the most disease resistant of the roses and even a ‘fail proof’ plant for landscaping. Now, even more recently, knock out roses in our region (Southeastern United States) have been contracting and dying of RRD. Since knock out roses have become so popular and are in over 60% of landscapes, prevention of RRD is going to be crucial. The only way to identify and prevent rose rosette disease is by having a trained professional inspect your roses. We pride ourselves in being current in the horticultural world and having the best trained staff for identifying, diagnosing, and solving these types of problems.