Flagging (dead branch tips) on jack pine and red pine may be caused by insects, diseases, or mechanical damage. In the Lake States, flagging is often the result of mechanical damage, sometimes girdling, caused when the cones are torn off by red squirrels.
Up to a three-year portion of the branch may be killed depending on where the cone was located. Drops of pitch can often be seen around the scar where the cone was torn off.
Damage caused by squirrels is most common in years when foods other than pine seeds are scarce and in areas where squirrel populations are greatest. The impact of this damage is usually insignificant and its occurrence need not be reported.