Christmas tree pests and weeds The pathogen often makes Douglas fir trees unsalable as Christmas trees and affects the Christmas tree farming industry. Douglas firs are also affected by "Phaeocryptopus gaumanni" which causes Swiss needlecast. Red band needle blight is a fungal disease which affects coniferous trees, particularly pine, with a worldwide distribution. The disease is caused by the fungi "Dothistroma septosporum". Since the late 1990s its appearance in the United Kingdom has increased, among the most affected species is Corsican pine and the disease has been a significant problem in Thetford Forest. Though the disease spread rapidly during September 2007 Christmas tree growers remained
Medium tree finch same. This reflects the fact that the two species feed on the same type and size of insect. The beak of the medium tree finch is intermediate in size between the small tree finch and large tree finch. All three species are found in the same habitat. The medium tree finch is threatened by introduced predators such as rats, mice, cats, and the smooth-billed ani, as well as habitat loss, which has occurred through clearance for agriculture. The introduced fly "Philornis downsi" is a significant threat to the survival of this species. Parasitic larvae of this fly live in the