Some species of pine, such as the Scots pine, are susceptible to dormant season "yellowing", which is generally countered with a green dye or paint.
The Christmas tree market burgeoned through the 1960s and 1970s, but from the late 1980s onward prices and the market for natural Christmas trees declined.
In the early 21st century, nearly 98 percent of all natural (non-artificial) Christmas trees sold worldwide were grown on tree farms.
Certain species of birds are also considered pests, including the pine grosbeak, which feeds on conifer buds, The Department of Agriculture's United States Standards for Grades of Christmas Trees took effect on October 30, 1989, covering "sheared or unsheared trees of the coniferous species which are normally marketed as Christmas trees".
Christmas trees can be harvested and marketed in different ways.