I have a number of euonymus with crown gall. I have sent photos to a number...

Asked September 17, 2013, 4:04 PM EDT

I have a number of euonymus with crown gall. I have sent photos to a number of nurseries in the area and have taken branches with galls to the staff at Sun Nurseries for diagnosis. I have a specimen paperbark maple growing about 4 feet from the closest infected bush and a Knock Out rose much closer on 3 sides. Several questions--Is the 15 foot paperbark maple in jeopardy? There was a paperbark seedling nestled in the euonymus that had a marble sized lump when I cut it our yesterday, but I don't know if it was crown gall. When I cut the Knock Out back this year, won't it most likely get it? I thought of removing the infected plants, but I gather the soil would still be a problem for 2-3 years and I would have to get every speck of soil too. I've been told that water carries it to other plants with breaks in the bark too . Suggestions?

Montgomery County Maryland shrubs crown gall on euonymous euonymous galls galls on shrub galls on euonymus crown gall on euonymus

3 Responses

Euonymus often get crown gall. Crown galls should be consistently pruned out or they will spread to a number of plants, including roses (though Knockouts seem to be pretty resistant.) If there are only a few galls on a few stems, cut the stems to the ground if you can and eliminate it entirely. Heavily infected plants should be removed. The bacterium is always around in soil, so that should not stop you from removing infected plants. The bacterium is also identified as a problem on maples.

When you prune, you should clean off the pruning blade with 70 % denatured alcohol from time to time, and you especially would want to do this between plants so you do not spread the disease.

ECN

We have one grouping of about 5 euonymus. When I noticed them this spring, the galls ranged from golf ball to baseball size. There were many on 3 of the plants, some on the branches and others had to partially dug from the ground. The least infected of the 5 now has marble size galls on several. Instead of digging them out, could I instead cut the ends to ground level and brush on woody growth killer? Several of them are most surely surrounded by the root system of the paperbark maple, I thought applying brush killer to the actual euonymus cut might cause less injury and possible infection to the maple than digging them out.

Your suggestion about using a brush killer on the cut stump is a good one. Either Glyphosate (Roundup/Kleenup) or Triclopyr, would work. Glyphosate may be the better choice since it doesn't move through the soil, and has more systemic properties than does triclopyr. The trick, however, is to paint the cut stump immediately with the chemical since the stump will form a callus very quickly and deny the chemical from going down into the roots.
LS