What is the white residue I am finding on White Pine trees? Is there anything I can do to rid the trees of it?
On the trunk, syrupy substance and on the branches is a cottony looking subtance which is also at the site of the damage on the trunk.
Answer
It sounds like you may have Pine Bark Adelgid.
Here is a description of the damage from the Michigan State Extension:
Infested trees can be recognized by the presence of patches of this white, cottony material on the smooth bark of the trunks and limbs and at the bases of needles or buds. Heavily infested trees may appear whitewashed. The insect uses its long, needle-like mouthparts to pierce the tree bark and feed on the sap. Feeding is limited to the bark of the tree.
Both websites linked above have great information about how to control this pest. Dormant oil sprays are a popular method, because they allow for pest control without harming beneficial insects. If you have other pines on your property you should also treat them, even if they do not show signs of white residue.
Courtesy of NYBG Plant Information
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