The War on Christmas is coming from inside the house. Or rather, the ground. Or rather, the water mold Phytophthora, which lives in soil and makes it a hostile environment for Frasier firs, colloquially referred to as Christmas trees. It's also known as "root rot."

The Associated Press reports that the fungicide-resistant mold, if not contained, could cost the U.S. fir tree growers hundreds of millions of dollars each year:

One study estimated the potential losses to Oregon's nursery and Christmas tree industries of up to $304 million a year if Phytophthora is not properly contained. Douglas and Noble fir are the dominant holiday tree species in the Pacific Northwest. In North Carolina, the No. 2 producer, it costs farmers up to $6 million a year, said John Frampton, a Christmas tree geneticist at North Carolina State University in Raleigh.

One North Carolina grower said his trees were first affected by Phytophthora following Hurricane Fran in 1996. Hurricane Ivan, in 2004, exacerbated the problem. A solution — for now, the only solution — lies in foreign fir trees, which are able to combat the fatal mold:

Growers in Oregon, the nation's No. 1 Christmas tree producer, have been experimenting with the Turkish fir for more than 30 years. That species and the Nordmann fir, also native to Eurasia, have shown promising resistance to root rot.

American firs are not the only trees suffering this holiday season. According to The New York Times, an infestation of beetles is threatening New Jersey’s pines. Until recently, the beetles had been killed by winter frost, but rising temperatures have allowed the insects to flourish for the past few years. Pine beetles have already destroyed tens of millions of forest acres in the Western U.S. and Canada.