IT’S IN THE GENES
Some kinds of trees, like the noble fir or Fraser fir, are better than others at maintaining moisture and keeping their needles once they’re in your house, says Gary Chastagner of Washington State University. But even within a given species, some trees are better than others, he said. Needle retention is an inherited trait: if a tree does well, so will the offspring that grow from the seeds in its cones.
SEEKING THE CHAMPS
At a research station in Puyallup, Washington, Chastagner works to identify individual trees that hold onto their needles best. He tests branches cut early in the fall, which encourages needle loss because they haven’t experienced cold weather. He lets them dry out and his team evaluates them after about 10 days, looking for branches that do not shed any needles. Needles start to fall off branches from some trees within three to five days when the branch is gently rubbed, even if they aren’t dry and brittle. A poor performer may lose all of them within a week.
GOOD BRANCH IS GOOD SIGN
If a branch does well, it means the tree has good genetics for keeping needles. So growers can seek out seeds from those trees to produce seedlings for future planting. These progeny should do well, too. With a federal grant, Chastagner is also working with others to identify genetic markers that indicate whether a tree will resist needle shedding. That would make the tree-screening process much faster and perhaps lead to breeding experiments to produce superior trees.
ANOTHER GLOBAL WARMING WORRY
Trees that experience warm autumns tend to have more needle loss later, Chastagner said. So if global warming leads to warmer falls in the future, it could be bad news for Christmas trees, he said. But since his studies focus on tree branches harvested before cold autumn weather sets in, they may identify trees that will do well in a warming world, he said.