One of our Photinina Red Robin- X Fraseri, has two or three unusual growths at the base of the branches as they go into the soil. Look like ‘barnacles’ but quite big about half a tennis ball size. They are ‘stuck’ to the brances and when we try to pull off no luck at all. The plant itself is ok does not show any sign of growth retardation. We have several of the same shrub on our boundary and no others are affected at all.
Nothing can be done, except to reduce competition of weeds or other plants and do not mulch around the neck of the tree.