Heavy is the Rose that Wears the Crown Gall

Growing roses is all fun and games (and splinters) until one of your roses winds up with crown gall. It sounds almost exciting, or like something you’d want to get. Perhaps a prestigious award, or a badge of honor. But alas, crown gall is a mark of death.

I don’t mean to be dramatic, but there are a handful of rose diseases that I take a very fatalistic and stern approach to. Crown gall is one of them. Unlike many rose diseases, crown gall is caused by a bacteria and not a fungus. This bacteria is highly contagious and can travel through the soil, making other roses in your garden susceptible to catching it too.

What is crown gall?
Galls are undifferentiated plant cells, or essentially tumors. Many galls are harmless and just make a plant look like it has warts, or some odd bumps. In the case of crown gall, however, the gall is formed at the crown of the plant, or where the stems and the roots meet. Crown gall can effect more than just roses, as it also can infect other woody plants too. Ultimately, crown gall winds up girdling the plant. Girdling is when a plant is basically being strangled, which in our case means the water and nutrients cannot flow freely, resulting in the death of the plant. I know, it’s pretty grim stuff.

Crown gall won’t necessarily kill the plant within a season or two, it may take more time. Regardless, don’t let that lull you into a false sense of security. As the cauliflower-looking gall grows bigger, it begins to harden. As it hardens, it cracks, and more of the contagious bacteria is sent into the soil. There may be no use crying over spilled milk, but I’ll tell ya’, I definitely understand if you want to cry over spreading, nasty bacteria.

How does a rose become infected?
In an effort to not be a total downer, there’s some good news. Fortunately, roses are only going to be susceptible to crown gall bacteria if there is an injury at soil level for the bacteria to enter through. However, there’s still bad news - An injury could range from anything from removing a cane, or stem, at ground level, to a rabbit nibbling at a stem that touches the soil, to a deer hoof carelessly knocking into and nicking a stem in touch with the soil. Creating an access point, sadly, isn’t that hard (sorry, sorry, but I stand by the fact that I wasn’t exactly a total downer!). That being said, that doesn’t mean that if you have a plant with crown gall and find an injury on a rose five feet away, that the healthy rose will definitely get it too. But who really wants to roll the dice on that one?

The task at hand
You could probably tell this was coming: We found crown gall on one of our roses. It was a pretty hard blow to me and my volunteers, but we knew what we had to do.The rose needed to be removed, and with it about two wheelbarrow loads full of soil. Jason Flynn, a member of our Horticulture team, joined me as a non biased, emotionally unattached individual who would not let his feelings (or, thankfully for us, lack-thereof) for the rose cloud his, or my, judgement.

Together, Jason and I tackled the removal of the rose. Jason cut back the unruly stems, while I went to work digging. As it became looser, and its hold on the ground beneath began to weaken, Jason dealt the final blow. He tugged it right out of the ground.

I’ve always been interested in the macabre, and my poor severed rose was no exception. Jason and I took a moment to look at the large masses that had formed around the crown. An oddity of nature, even if it’s one that’s not helpful, or beneficial, is always worth investigating. While digging, part of the gall became loose, which allowed us a view of the inside of the mass, pictured below.

Once we finished conducting our examination of the rose and its gall, we dug up the soil, loading it into a wheelbarrow to be brought offsite. By removing the soil, it was our goal to have removed the bacteria as well, ideally before it had a chance to spread.

Since we were dealing with contaminated materials - both the rose and soil - that meant any tools that came into contact with either of them were also potentially contaminated. Cleanliness is an important part of horticulture, and absolutely so at a time like this! We washed out the wheelbarrow and the back of our work vehicle once the contaminated soil was discarded.

We returned back with our vehicle loaded up with fresh, clean soil and compost. However, before we could put it in our wheelbarrow, we rubbed our shovels and pruners down with rubbing alcohol to sanitize them as well.

With freshly cleaned tools, we set out to fill in the crater we had created. Jason, typically reaching about 5’11” in height, lost a few inches to demonstrate how much we dug out.

Thankfully, the gaping hole was only there a short while. We brought back our compost and soil and added it in, helping bring the landscape back to some sort of normality. Soon, we will replant with the same cultivar, or cultivated variety, as to not disrupt our design.

Fortunately, replanting with the same type of rose will not necessarily mean that the upcoming rose will get crown gall too. An important thing to remember about crown gall, is that most roses are susceptible to it, and it is not necessarily a sign of a rose that is a poor performer, just a victim of circumstance. However, if you find crown gall in your home garden, you may want to look into a different sort of plant for the location, to minimize your chance of planting something else that will potentially be infected. Since our infected plant was a rose within our rose garden, we are willing to be a little risky to keep up with our intended garden plan.

While no one wants to see crown gall, hopefully the only place you’ll ever have to see its ugly face is in the photos in this blog - and not in your (or our!) garden.

See you in the gardens!