Answer: Have a look at other trees in your neighborhood. Are they all doing the same thing? Pines do drop their old needles this time of year, so if the new growth looks healthy and green, then it's probably just the ususal pattern. (If I remember correctly from botany class, the needles on white pines last only 2 years before they drop.) If your trees look significantly different, or are more yellow overall, than the ones around you, then you may have cause for worry.
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