bore

Can anyone help answer what evil pest is doing this to my tree and how I can help it from dying? Is it too late? Seems to be only in the branches, not the trunk. Located in Northern California rural land, tree is a fruitless mulberry - about 15 years old.

Asking $45 shipped

newb here ... what are the design differences between a low kickback bar, and a not-so-low kickback bar ? nose diameter ? and on a related note, what is the most important factor when making a boring cut ( in terms of chain type, bar type, etc) is it easier to bore with semi-chisel ?