120 U.S. DEPT. OF AGRICULTURE MISC. PUB. 939 



a number of places. From such lists, distribution maps can be made. 

 At the same time, the maps may show the distribution of reporting 

 pathologists rather than that of the disease. Negative reports may 

 be significant only if a qualified person has made a diligent search. 



Such lists may not disclose diseases which appear innocuous in 

 one country but which might be dangerous in others (such as the chest- 

 nut blight in east Asia). However, research, as discussed later, may 

 bring these to light. An example of such an annotated list is given 

 for the United States by Spaulding in USDA Agricultural Handbook 

 No. 139 where 33 diseases come under the heading "American Forest 

 Diseases Potentially Dangerous to Forests of Foreign Countries." 



Much can be learned by a study of surviving exotic trees in planta- 

 tions already made, as Spaulding has done. 



List of Key Men in Each Country. — A list is being prepared of 

 one or more men from each country active in forest pathology. These 

 men will exchange critical information, arrange for research on an 

 international basis between suitable individuals, and advise in case of 

 an outbreak. 



Strengthening Quarantines. — Plant quarantines are the accepted 

 bulwark against the entry of dangerous tree diseases into a country. 

 Modern air travel greatly increases the chances for distributing patho- 

 gens from one country to another. Many foresters are concerned about 

 the effectiveness of quarantines because, no matter how well they are 

 administered, dangerous pathogens may get through. Forest patholo- 

 gists have an obligation to supply to quarantine officials a list of the 

 most dangerous pathogens and to describe the diagnostic symptoms by 

 which they may be recognized. At the same time interferences with 

 commerce, travel, and the exchange of scientific materials need to be 

 held to a minimum compatible with protection. More research is 

 needed if quarantines are to achieve maximum dependability. 



Organizations Now Operating. — Various organizations deal in 

 one way or another with certain aspects of these foreign tree disease 

 problems. The names of some important ones follow : European and 

 Mediterranean Plant Protection Organization ; Moscow-Peking Con- 

 vention: Plant Protection Committee for the South East Asia and 

 Pacific Region ; Inter- Africa Phytosanitary Commission ; Organismo 

 International Regional de Sanidad Agropecuaria (Central America) ; 

 Plant Quarantine Division, ARS, U.S. Department of Agriculture; 

 and Division of Plant Protection, Canada Department of Agriculture. 

 In addition, the Food and Agriculture Organization of the United 

 Nations in Rome is interested in reducing the spread of forest patho- 

 gens from one continent to another and can supply the name and 

 address of the quarantine services in all member countries. 



Cooperative International Research. — For a number of critical 

 problems no one knows the answers. To secure them, cooperative re- 

 search is essential between men in different countries. Obviously, one 

 cannot move either the pathogens or the living trees that might carry 

 them from one country to another except with extensive precautions. 

 However, disease-free selected or treated seed can go from one country 

 to a suitable place in another country with relatively little danger. 



Some important topics for research follow: 



(a) Host ranges. The different kinds of trees attacked by critical 

 pathogens need exploration. In some cases related ornamentals carry 



