HOA Newsletter – June

If You Love Roses, You Should Know About Rose Rosette

http://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/images/Pests/Rose_Rosette81.jpg

Photo courtesy of Missouri Botanical Garden

By Nancy Caldwell, Loudoun County VCE Master Gardener

Roses add undeniable beauty and interest to the garden. And the newer varieties promise disease resistance and long bloom times.

Sadly, disease resistance does not mean disease free. Even the popular Knock-Out roses are susceptible to a deadly virus known as Rose Rosette Disease, or RRD. Spread by tiny wind-born mites, RRD is popping up with increasing frequency in our communities and home landscapes.

How do you know if your roses have the disease? You may notice thicker canes with larger, more numerous thorns. There may be dark red foliage at the tips and discolored, multi-branched leaves, known as witch’s broom. Flowers and buds may be discolored, or disfigured.

Unfortunately, once a plant is infected it can’t be cured.  It usually dies within a few years; however, if left in the landscape a diseased rose can infect other healthy roses nearby.  While some gardeners believe that pruning out the diseased canes can possibly save the plant if caught early, this method hasn’t been proven. Virginia Tech and the Virginia Cooperative Extension recommend removing it completely, including all root material. The diseased plant should not be recycled or composted, since the virus will survive and could end up as mulch in someone else’s garden. Instead, dispose of it in the regular trash or burn it (if allowed in your community).

While RRD can’t be cured, it may be possible to prevent your roses from becoming infected by applying horticultural oil or insecticidal soap to plants once a week until July when mites are most active.  Watch your plants carefully—if you see signs of the disease act quickly to remove it from the garden and dispose of it properly. Then disinfect your pruning equipment with bleach or isopropyl alcohol.

It is possible to replace the diseased rose with another, but take care to remove any remaining roots or plant material from the area.  A safer bet is to find a different plant to take its place. The good news? Rose Rosette only affects roses, and will not harm other plants in your garden!

Learn more about Rose Rosette online at https://pubs.ext.vt.edu.