NEW YORK - With Christmas over, it's time for another Yuletide tradition: Cleaning up the needles that are falling off the tree. Consumers consistently cite messiness as one of the most common reasons they don't have a real tree, says the National Christmas Tree Association.

Keeping a tree well-watered goes a long way toward minimizing the needle problem. But scientists are trying to find ways to make trees less messy and keep them fresh longer.

Some kinds of trees, like the noble fir or Fraser fir, are better at maintaining moisture and keeping their needles, says Gary Chastagner of Washington State University. But needle retention is an inherited trait.

At a research station in Puyallup, Wash., 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. If a branch does well, it means the tree has good genetics for keeping needles. Growers can seek seeds from those trees to produce seedlings for future planting. The 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 tree screening faster and perhaps lead to breeding experiments to produce superior trees.