DANGEROUS INTERNATIONAL FOREST TREE DISEASES 23 



are pleased to have Dr. B. K. Bakshi of India making a detailed study 

 tour of forest disease research establishments throughout Canada. 



Consultations between Canadian and American pathologists is fre- 

 quent and three international conferences held annually in the eastern, 

 central, and western regions of Canada and the United States provide 

 excellent opportunities for informal discussions of problems. At the 

 first meeting of the newly formed North American Forestry Commis- 

 sion scheduled for Mexico City, July 24 to July 29, 1961, forest diseases 

 constitute an important part of the agenda of business. This new 

 commission will provide increased opportunities for the mutual ex- 

 change of information between pathologists in Canada, the United 

 States, and Mexico and should strengthen the contacts of scientists in 

 North America with those of other countries. 



Forest Disease Surveys 



The Forest Entomology and Pathology Branch maintains a per- 

 manent national organization for continuing surveys of forest diseases 

 and insects. The primary objectives of the forest disease survey are 

 to detect, identify, record, and interpret the significance of tree diseases 

 in Canada. 



This survey establishment includes some 75 forest ranger technicians 

 located in the various regions of the country whose duties are to collect 

 and appraise the damage caused by forest diseases and insects. Forest 

 personnel of provincial governments, industries, and other agencies 

 are active cooperators in this program. These activities are coordi- 

 nated and directed at regional and national levels by research officers. 

 The published results of 10 years (1951-60) work have verified the 

 usefulness of this methodical appraisal of diseases. The results have 

 proved valuable in developing control procedures, in preventing the 

 establishment and spread of new diseases, and in providing a founda- 

 tion for the planning and development of the disease research program. 



Typical of the regional disease survey contributions included in the 

 Annual Report of the Forest Insect and Disease Survey for 1960 (3) is 

 the report from British Columbia (6). A total of 2,049 disease col- 

 lections were made from more than 40 tree species. Under "Important 

 Diseases,"' the following are discussed : weather injury ; foliage diseases 

 caused by Hypoderma deformans, H. laricis, and Rhabdocline pseu- 

 dotsagae: two new diseases introduced from Europe, pine twist rust 

 (Melampsora pinitorqua) and pear-juniper rust (Gymnosporangium 

 fuscum) ; willow blight; dying of weeping willow; Mel am psora rust 

 of Douglas-fir and poplar; diseases of exotic trees: and disease con- 

 ditions in forest nurseries. Under the title of "Other Noteworthy 

 Diseases,'' 20 additional diseases are tabulated according to host, or- 

 ganism, locality, and remarks. It is evident that the results obtained 

 from the survey are of interest to pathologists in other countries be- 

 cause many of the pathogens reported have worldwide distribution. 



During recent years detailed surveys of native and introduced dis- 

 eases have included the Dutch elm disease, white pine blister rust, 

 root rots caused by Fomes aimorns and Arm Maria mellea. willow 

 blight, the beech-bark disease, various decay fungi, needle cast and 

 rust fungi, poplar canker fungi, dwarfmistletoes and their parasites, 

 and many others. 



Special surveys and appraisal studies of diseases of Douglas-fir 

 plantations have been underway for the past few years (4)- In 



