Rose Rosette disease in the Knockout Rose is very common viral disease here in SE Virginia now (and I know it is common in other states as well). It is a disease that affects many other roses such as the multifloral, climbing, and even hybrid roses. I have had first hand experience with this rose disease and its spread and I can tell you – THERE IS NO CURE OR SAVING THE PLANTS.
I tried. Many young roses will die within a season or two. My climbing rose started to decline rapidly and the rose buds shriveled up as the disease took over. Knockouts, however, will live for at least 3-4 years blooming and growing and displaying the beautiful burgundy new growth and witches broom (thorns).
I dug up and removed the diseases roses, however, I have neighbors who refuse to remove their diseases Knockouts because they still grow and bloom. I tried to explain to them that this disease affects the soil and is transmitted to other roses in the vicinity and not just in their yard. What you are going to be shocked at is that a few of these homeowners received them FREE from our Homeowners Association and the maintenance team who was digging them up because I had told them months before the roses were diseased!
Ironic, huh?
The supervisor or manager of the maintenance team has been a landscaper for years and he and I have butted heads. I simply tell him I am not a landscaper – I am a naturescaper and I work with nature. I no longer go to my Homeowners Association or to the maintenance department any more because they do not care that the deer eat the native plants to survive, that Round UP should not be sprayed in native areas, and that diseased roses and plants should not be given away!
Oh shoot I digressed, sorry.
In these videos, I share with you what to look for and how to spot Rose Rosette disease. Knockouts are very hardy plants and even when consumed by this disease they will bloom and grow. The new growth of deep burgundy on Knockouts is gorgeous but it is deadly to other roses and to the soil. Wherever the diseased roses grow, the soil is no longer viable for roses in the future. So you will have to find a new location for any rose bushes in the future.
If you Google Rose Rosette Disease you will find information about the very small Eriophyid Mite that spreads this viral disease. This disease can wipe out a row of roses in one season so if you see the signs early you may be able to save other roses before it spreads. The female Eriophyid mites will be hard to see and they hide near new growth shoots and in the bud at the end of the stem (or terminal bud/apex) where they lay one egg per day for a month. It is interesting to note that the male Eriophyid mites do not have wings but are carried throughout the garden by the wind, garden tools, and even your clothes.
You can use organic horticultural oils and insecticidal soaps in May- July on non affected roses to try and stop the spread. However, once a rose has the disease you must take immediate action to removed them and dispose of them properly (as seen in this video) 
A tip if you want to grow roses, do not plant them too close together. This can be a precaution to help you keep Rose Rosette disease from spreading in the garden.
Good luck and I hope this post help. I know it is sad when you have to dig up and destroy a plant. However, it must be done to avoid any future spread and destruction of nature’s beauty. Thanks for stopping by!
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