Q: What would cause these bumps on the trunk of a redbud tree?
A: My friend Bill Blum is a tree connoisseur. He notes that:
“the tree is a fairly significant size for an Eastern redbud. So it must be a significantly older tree. Most redbuds succumb to Botryosphaeria canker in these parts when they get older. The only thing I can think might be happening is epicormic branches (foot-long tufts of leaves, which eventually wither, die and fall off) or epicormic flowering. On redbuds the epicormic flowering is termed ‘cauliflory’. Michael Dirr has it in his “Manual of Woody Landscape Plants”. https://vnps.org/wildflowers-of-the-year/2013-woty-redbud/
Also, a pub from the VNPS: https://scholarship.richmond.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=1130&context=biology-faculty-publications
The knots might once have been a burst of leaves or flowers in the spring.”
Art Morris is a Board-Certified Master Arborist at New Urban Forestry. He says:
“I’ve seen those before and believe that they’re just a series of small burls. Depending on who you ask, they’re caused by bacteria, mechanical damage or virus. I tend to lean toward the idea of a virus for a couple of reasons. First, they’re located almost in a line that we could imaging follows the vascular pathway up the tree trunk. So if the tree was infected, I could imagine the virus could be transmitted up or down the trunk in that pattern. Second, the small burled areas remind me of other viral deformities like fasciation.”
There you have it: two different opinions.
I have no idea who is right but I am certain these two guys are smarter than me!