Ask a Consulting Arborist Q&A: Tree Planting Tips and Species Recommendations

Q: Any suggestions for gall-resistant trees?

Thursday, December 31, 2015  

Q: I live in East Jewett, New York, and my house is at an elevation of 2,500 ft. The surrounding hills go to 4,000 ft. We're in the northern Catskill mountain range, so it's a bit cooler up here than down the mountain. We plant for Zone 4-5 depending on the site.

Regrettably, I think my mystery growths are crown gall. I've been searching online and they look just like the crown gall pictures. The nursery that sold us the tree two weeks ago has a good reputation and we've purchased other plants there with no problems. We called them, but the owner is on vacation until next week. After my own research on crown gall, it appears infected trees have to be removed and destroyed and the planting site remains contaminated for years. If my diagnosis is right, this is obviously a big disappointment.

If you have any suggestions for gall-resistant trees or shrubs that might do well in the weeping willow site (clay soil, high water table, full sun, near a runoff), I'd appreciate it. I don't want to kill another tree, but I'd like to replant as soon as it's safe to do so.

A: From your description, the issue with your willow does indeed sound like crown gall. However, it would be a good idea to contact your local cooperative extension agent for instructions on how to submit a tissue sample for confirmation. A list of New York (Cornell Cooperative Extension) offices can be found here: http://www.cce.cornell.edu/learnAbout/Pages/Local_Offices.aspx

That said, below is a short list of suitable trees based on your soil, site, and hardiness zone description. Additionally, I have added notes where trees have been specifically listed as resistant to the disease by various universities.

Devil’s maple (Acer diabolicum) listed as “occasional/rare” occurrence
Ohio buckeye (Aesculus glabra)
Black alder (Alnus glutinosa)
River birch (Betula nigra) listed as resistant or immune
Bitternut hickory (Carya cordiformis)
Common hackberry (Celtis occidentalis)
Black ash (Fraxinus nigra)
Golden raintree (Koelreuteria paniculata) listed as resistant or immune
American larch (Larix laricina) listed as resistant or immune
Sweetbay magnolia (Magnolia virginiana) listed as resistant or immune
Tupelo (Nyssa sylvatica) listed as resistant or immune
Pond cypress (Taxodium ascendens)
Scotch elm (Ulmus glabra)
Cherrybark elm (Ulmus villosa)

Responder: Jason Miller, RCA #526, Cinnaminson, NJ