A hobby I really love is gardening. Roses, In particular. My place has at least forty rose bushes of many different colors and sizes. From the fragrant Julia Child to the red Lincoln rose, my yard is the home of all sorts from early Spring until late Autumn. But also my property, which includes several acres of pasture land and a forest, also hosts a great many wild roses that cling to trees and grow in bunches everywhere around the farm.
In short, I live in a rose gardener’s haven.
Please note that I do not say that I live in a rose gardener’s paradise. Because anyone who’s ever dealt with roses (even the extremely hardy knockout rose variety that was introduced in a few years back) know that roses require constant care. Removing old blooms (called “dead-heading”) to encourage more blooms, keeping the rose pruned, and fighting off various pests like Japanese Beetles (the thorn in my side) requires dedication and effort.
I was so sad and aggravated when several years ago, I found a few of my rose bushes had been infected with Rose Rosette, otherwise known as witches broom.
To those of you who don’t garden or work with roses, it is quite difficult to describe exactly what witches broom is. Basically, witches broom is a virus that is fatal to the rose bush. A rose that contracts witches broom may survive up to twenty-two months after infection, but it’ll eventually succumb to the virus. Sadly, there is no cure. Also, the virus is really contagious to other roses as well, so the longer you leave an infected rose bush, the more likely you’ll probably lose the rest of your rose bushes. The effect it has upon the foliage brings about its other name of witches broom. The disease causes vigorous growth in the cane or canes infected by the virus. The foliage becomes distorted and looks frazzled. Also it turns a deep red to almost purple in color and then changing to a more distinct and brighter red. The new leaf buds fail to open and look a bit like rosettes, thus the name Rose Rosette.
Below is a list of some of symptoms to look for:
- Excessive thorniness, small red or brown colored thorns
- The appearance of dwarfed or stunted growth
- Elongated and/or thickened canes
- Bright red leaves** and stems
- Stem bunching or clustering, witches broom appearance
- Distorted or aborted blooms
- Under-developed or narrow leaves
- Perhaps some distorted canes
- Dead or dying canes, yellow or brown foliage
- A combination of the above
**Note: Deep red colored leaves may be totally normal, as the new growth on many rose bushes start out with a deep red coloration and then turns to green. The difference is that the virus infected foliage keeps its color and can also become smeared with different colors, along with vigorous but unusual growth. A normal red shoot will eventually bloom into a new rose as well, but a shoot infected by witches broom will not.
Cause of Witches Broom in Roses?
The virus that causes witches broom is believed to be spread by tiny mites named Phyllocoptes fructiphilus. They are not like the spider mite most of us are familiar with, as they are far smaller. So while Miticides can be used effectively against spider mites, don’t expect them to be effective against this tiny mite. These little pests can travel easily with the wind, so mites on an infected rose can spread more mites to other roses in a simple breeze.
How to Treat Witches Broom on Roses
Once you’ve determined that a rose bush has become infected with witches broom, the first thing you need to do is to find out how badly the rose bush is effected. Several years ago, I discovered two rose bushes that had witches broom. One bush had only one branch with evidence of witches broom, while the other rose bush had over half of its branches infected. I noticed that these two particular rose bushes were near my fence, just beside the pasture. I walked through the field and discovered eight wild rose bushes were also infected with witches broom. Most of these bushes were small, but two in the field had been there for years had this terrible growth over half of the branches.
Once I learned how much of the infected area there was, I got to work immediately. As a great amount of the rose bushes just described were badly infected, I had no choice but to uproot them completely. I covered each individual rose bush with a trash bag (TIP: use trash bags that are designed for lawn care. The stronger the bag, the better the chance that the virus won’t spread while you are in the process of digging the rose up. Even accidentally shaking the rose bush while digging it up can spread these mites. I made sure to cover all the infected roses with the trash bags first before even starting to dig them up. I’m glad I took that precaution, because a summer storm showed up while I was barely half-way through the process of removing the infected roses. If I had left the roses uncovered, the winds from the storm would have definitely spread the disease to other rose bushes.
After the roses are covered and secured in the trash bags, I dug the rose bushes up using a shovel and trowel. Preferably, you may wish to treat clean your tools thoroughly after using them on roses infected with witches broom. I watched mine off and then soaked them for a few minutes in bleach, just for good measure. Again, the best thing to do when you are certain a rose bush has the Rose Rosette virus is to remove the bush and destroy it along with the soil immediately around the infected bush, which could harbor or allow overwintering of the mites. Again, I dug up the dirt directly around each infected rose bush and disposed of it accordingly before spraying the remaining soil with a spray bottle of bleach to ensure that any mites still hiding in the soul are destroyed. (TIP: Don’t add any of the infected plant material to your compost pile! You’ll just spread the witches broom to the compost and thus eventually to the rose bushes in the area.)
However, there is a way to save a rose bush if it’s only partially infected with witches broom, just like I did with two of my rose bushes that only had one or two branches infected. For those rose bushes, I covered the infected branch with a trash bag (again, to prevent the mites from spreading). Then, I cut the infected branch off at the base (or root) of the rose bush using cutters pre-soaked in bleach. I then removed the infected branches and watched the two rose bushes very closely for any sign that the witches broom would reappear. If it had, then I would have been forced to dig up the whole bush. But, much to my delight those two roses I treated were no longer bothered by witches broom. The infected branches that were cut off eventually grew back without the witches broom, and they continue to bloom to this day.
Thankfully, my first encounter with witches broom was my last so far. Every week when my roses are in bloom, I make a point to look each of them over for any pests and/or disease, including witches broom. As I learned from my own experiences, you have to be vigilant in identifying the cause of any affliction your roses may suffer from and then treat the problem quickly and decisively to ensure the continuing health of your rose garden. It seems like a lot of work going around checking your roses for signs of witches broom, but believe me when I tell you that it’s even harder work to replace your roses to this virus. Keep your eyes open and remember that spotting and identifying the problem early on will save you a lot of trouble in the future. Take your time to literally “stop and smell the roses!” This step, more than any other, will help you stop witches broom before it starts!
My name is Chessia Cox, Attorney at Law. Practicing law in Southeastern Tennessee. By the way, did I mention I love my roses?