Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Observations on Forest Pathology in Great Britain and Denmark.

Abstract

The most serious injury to Pseudotsuga taxifolio, (douglasi) observed by the author in 1925 during a visit to Britain to investigate the diseases of forest trees was caused by Chermes cooleyi, Gill., originally introduced from North America. While this Aphid rarely, if ever, kills the trees, they become stunted and weak. In North America, where it also attacks Sitka spruce [Picea sitchensis], it is practically innocuous, and the introduction of its parasites into Britain might be of value. Chermes (Dreyfusia) nüsslini, Börner, which attacks silver fir [Abies] was apparently introduced into Britain from the Continent, where it is widely distributed, but not very injurious. In 1925 it was widespread in Britain, the damage being so severe that the further planting of silver fir may have to be discontinued.