Diseases of Douglas fir (Pseudotsuga spp.)

Abstract

Species of Pseudotsuga occur in North America south to Mexico, and in China and Japan. The only species extensively grown in Britain (and in the rest of northwest Europe) is the Douglas fir, P. menziesii, a native of western North America. P. menziesii exists in three main forms or varieties, sometimes separated (though intermediates may be found), as var. menziesii (the coastal or green Douglas fir), var. caesia (the Fraser River, intermediate or grey Douglas fir) and var. glauca (the Colorado or blue Douglas fir). The green Douglas fir is a fairly important forest species, which grows well on suitable sites. The blue Douglas fir is grown in some parks and gardens, but is not extensively planted because of its slower growth and susceptibility to the needle-cast fungus Rhabdocline pseudotsugae.