Christmas Tree Pests and Weeds - Insects

Insects

The conifer species used and cultivated as Christmas trees are vulnerable to dozens of different pests, most of which cause cosmetic damage to the trees, important in the Christmas tree industry. The Balsam woolly adelgid (Adelges picae) are small soft-bodied insects which attack the Fraser Fir. The insects appear as white, woolly spots on the tree and are fatal to the fir if left untreated. The woolly adeligid was native to central Europe where it affected the silver fir; it was introduced to the United States, where it has no known native predators, before 1900.

Balsam twig aphids (Mindarus abietnus) are another type of tree pest which affects fir and spruce trees in the spring. The aphids can cause stunted growth in trees with heavy infestations rendering badly damaged trees unsellable. Other species of adelgids also infest fir trees, those include the pine bark adelgid, the Cooley spruce gall adelgid (Adelges cooleyi), and the Eastern spruce gall adelgid. Another serious pest are bagworms. These pests can defoliate a tree completely if present in large enough numbers. Additionally, the damage caused by the silk of bagworms can last years.

Invasive insect species such as the pine shoot beetle and the gypsy moth also threaten Christmas tree crops. Gypsy moth infestations in Canada required restrictions and requirements to be placed upon Christmas tree growers with plantations in "gypsy moth regulated areas". The restrictions and requirements included ongoing site monitoring, active moth eradication by the grower, accurate record keeping, and government directed moth eradication programs. Failure to abide by the rules could result in revocation of the "approved grower" status from the Canadian Food Inspection Agency.

The major types of conifers cultivated, pines, Douglas-firs, true firs, and spruce trees, are all affected by some types of insect pests. Douglas-firs are most vulnerable to the Cooley spruce gall adelgid. The true firs are most susceptible to insects such as the Balsam gall midge (Paradiplosis tumifex), and the Balsam twig aphid. Species of spruce trees face assault from insects such as the White pine weevil (Pissodes strobi), Cooley spruce gall adelgid, and the Pine needle scale (Chionaspis pinifoliae). The final category of Christmas trees, pines, are commonly susceptible to insect infestation and damage from the Pine root collar weevil (Hylobius radicis), Zimmerman pine moth (Dioryctria zimmermani), pine needle scale, and white pine weevil.