What is this ?

[CrazyEd]

My brother in law sent me these pics? Anyone know what this is ?

 

[White Oak]

burr knot I think

 

[Prof.Kent]

Roots.
Burr knots develop when adventitious roots start to form on the aerial parts of the tree. At first only a single root initial may form, but over time more and more root initials develop in the affected area and the burr knot increases in size. It may take a year or two before the adventitious roots rupture the bark.
Also, avoid the use of tree guards that fit around the trunk as they provide shade and increase humidity, which promote burr knot growth. When burr knots are visible, the root initials can be cut out using a knife, file, or rasp if only a few apple trees are affected.

 

[Prof.Kent]

Getting to the Root of Burr Knots on Apple Trees (Michele Warmund)

ipm.missouri.edu

 

[CrazyEd]

Thanks !