What accounts for these rare, odd branches in Ponderosa pines?
About 1 in 3,000 of the Ponderosa pines in Shevlin Park (Bend, OR) have one or more bizarre branches (see photos). The branches emerge from the tree trunk about 6 to 15 feet from the ground, and have a large diameter. They quickly ramify into many small contorted sub-branches. Could this be a mutation? A response to environmental stress? Something else?
Deschutes County Oregon
hello, that is likely caused by western dwarf mistletoe, a parasitic plant that is common in Ponderosa pine.
I've attached some photos that represent the deformation that can occur, with one picture of the aerial shoots of the mistletoe
Scientific name is Arceuthobium campylopodum
The branches are infected by the sticky seed of the dwarf mistletoe when young, and they may slowly deform over many years.
Here is a document:
Thank you! I will look for the mistletoe next time I am there.
Yes, the aerial shoots will only be on the living branches, so look on deformations that are still alive.
PS. The USFS has a great forest pathologist in Bend, Brent Oblinger.