Oddities of gall

I tried to send this to Dr David Zlesak via email a couple of times, but being I never heard from him, it probably ended up in a spam file somewhere. So hopefully he will see it here.

He wrote an article titled “Behind the Scenes Efforts” that was published in the September/October issue of the American Rose. A very well article filled with a lot of good information.

In the article he mentioned that “the bacteria that leads to crown gall can become systemic”. I had those same thoughts when I saw this rose bush and wondered if the gall bacteria from the soil could be taken up along with the nutrients thru the cambium layer to the leaf axils where it appears, on the photo, that it grows and produces all those small galls. In other words, I know that systemic chemicals can move up into the plant, so can bacteria move up as well?

Is what I am seeing on this photo, a systemic outburst of crown gall? I cut these from most every stem at the same time from ‘Liverpool Echo’, one of my floribundas. I know that there is crown gall in that bed as I have seen gall on the bushes a number of times, but never to this extent. Now I know that I have at times had infected pruners, but I know that I would never make this many cuts on each cane!

John Moe

John, I have frequently seen infection as you have photographed particularly on the 4’ weeping standards of Meilland “landscape” shrubs we used to obtain from Otto & Sons. It has also been VERY common on Ballerina, The Fairy and all the Flower Carpets I dealt with for years in the Los Angeles area. It’s the strongest reason I completely avoid any breeding line containing Ballerina and The Fairy (Carpets, Drifts, etc.) as those galls appear almost over night.

Any guesses as to why?

Not that it’s an issue here, but always interesting to know of potential issues of things I’ve picked up (Carpets in an attempt to recreate something akin to Raspberry Rugostar since that’s never coming here…until I get a fixed line of juvenile blooming rugosa I’m going to explore every demonstrated potential pathway)


Of the varieties you mention that have had this infection, have you propagated any cuttings from them? If so, would this “gall?” appear in them?

No sir. Once I see gall, I don’t mess with the plant. The most I would do with them was remove and trash them.

Hi John!

I’m sorry I didn’t see your email! This is sad to see so many aerial galls… At a National Clean Plant Network meeting one year we had a crown gall expert (his main crop is grapes) come and speak with us about the life cycle and spread of Agrobacterium tumefaciens. It sounded like the bacteria containing the plasmid that leads to crown gall can live in plants, but not cause galls until something triggers it, so roses that look normal can also be positive for Agrobacterium. On the plasmid are three key genes (an auxin, cytokinin, and opine gene) that can get transferred into the plant DNA to lead to the gall formation. The two hormones (cytokinin and auxin genes) lead to cell division and enlargement for the tumor and opine is a preferred food source for the bacteria. Those genetically altered cells are basically triggered to continue to make tumor tissue the rest of their existence and existence of their subsequent daughter cells.

From my understanding some of the leading rose nurseries have tried to proactively combat it by having their key cultivars clean in tissue culture (tested clean of key viruses and the bacterium) to use as elite stock plants they take out of culture periodically. It seemed in the 1970’s there were big outbreaks and at times since. Some of the more recent outbreaks from my understanding have related to some propagators recycling their water for water conservation and then the Agrobacterium spread through the trays of young liners. The liners were used as stock for more cuttings before they went out the door and were brought to bareroot fields (impacting that soil), sometimes to container nurseries to grow them to sale, etc.

In the past a good friend bought some roses from a pretty reputable smaller sized own root nursery. Soon after buying a rose and having it in its original container yet, saw galls at the base of the plant (they couldn’t get to that size in the limited time she had the plant). The nursery was testy with her and said it must of gotten it once at her place. It was sad to hear about the lack of taking it seriously and minimizing the customer’s concerns. My friend was most interested in letting them know to protect themselves and fix the issue than fight for what she paid for the single plant. Sometimes people are so self focused and defensive they can’t take constructive feedback and cause themselves more harm… Perhaps it is in the soil where the stock plants were and they took cuttings and some was triggered to make galls as a young plant in the media they used??

Perhaps it would be valuable to test for Agrobacterium in plant tissue proactively in nursery production before galls are seen. I suspect without seeing a big outbreak of galls it is easy to not think about it and not consider the pathogen could be present systemically.

Pictured are some galls at nodes of a rose trained as a climber 4-5’ off the ground. That’s interesting how nodes with axillary buds seems to be a favorite place for galls to start. Perhaps there is something unique about the biochemistry of those cells that triggers the process??
6 09 08 crown gall on rose stem alba meidiland.jpg

I think that this is the article that Dave is referring to:

Thanks Henry for the link to this article.