"Alan Sung" wrote:

A local nursery said they use a systemic such as Merit. They sprinkle around
their white pines. Then these white pine borers (of which there are a bunch)
die as they attempt to eat the wood.

It is too late to treat the infestation. The best procedure is a
prophylactic treatment to prevent the infestation and removing and
destroying infested material such as the previous poster mentioned:

"Mike LaMana" fake@MikeatHeartwoodConsultingdotnet wrote:

Your white pines are infested with White pine weevil - a beetle that lays
eggs on the terminal branch. The eggs hatch and the larvae bore into the
wood of the terminal branch in spring. Symptoms you see express in the
summer when the damage is done.

Depending on state law the way to go about this is to treat with a
repellent insecticide in early spring. Things like Talstar, Lindane,.
permethrin, etc have been used for this in the past.
best to prune out the dead terminal, and trim the remaining live laterals
to establish a new leader.

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