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



operation, and research can do much to slow down or even to prevent 

 more catastrophes like that caused by chestnut blight in America. 



Summary 



1. A directory of critical diseases in each country is needed. For 

 example, in the United States Spaulding lists 33 diseases potentially 

 dangerous for other countries (USDA Handbook No. 139). 



2. A list of key men is essential. At least one man per country 

 should assemble and distribute information. 



3. Strengthening quarantines is imperative, but interference with 

 commerce should be minimal. 



4. Existing organizations are adequate. 



5. International researches essential for effective operations in- 

 clude : (a) improved methods for diagnosing diseases and the prepara- 

 tion of authoritative host ranges of dangerous fungi; (b) under- 

 standing of alternate hosts of rusts; (c) the critical importance of 

 environment (e.g., temperature, moisture, light, and mineral nutri- 

 tion), of seasonal development, and of microclimate to epidemic out- 

 breaks; (d) the characterization of agents disseminating pathogens, 

 especially insects; (e) the unmasking of seemingly innocuous patho- 

 gens (e.g., chestnut blight) by suitable foreign plantings; (f) im- 

 proved eradication procedures to be developed where the diseases are 

 rampant; and (g) the development of elite and resistant varieties. 



6. Improved cooperation between agricultural experiment stations 

 and forestry research stations would be mutually beneficial. 



DISCUSSION AND RECOMMENDATIONS 



There was general concurrence with Professor Hiker's appraisal 

 of the need for international cooperation to lessen the intercontinental 

 spread of forest pathogens and with his suggestions for future ac- 

 tions to that end. 



The Working Group agreed unanimously to this plan of action: 



1. To stimulate the preparation of annotated lists of dangerou? 

 forest diseases in all continents. 



2. To draft a roster of leading pathologists in all continents 

 to whom may be sent inquiries about local forest diseases and 

 information on threatening diseases. 



3. To advise existing plant quarantine organizations of the 

 potential hazard of forest diseases in other countries and con- 

 tinents. 



4. To emphasize the need for increased research on forest dis- 

 ease prevention and control in all continents. 



The Working Group approved a proposal that an international 

 symposium should be organized to consider the particularly danger- 

 ous forest diseases of all continents and to recommend measures to 

 lessen or prevent their intercontinental spread. It was also recom- 

 mended that the Union should be requested to ask FAO to sponsor 

 such a symposium at an appropriate time and place. The Working 

 Group will assume all responsibilities for arranging for the tech- 

 nical subject matter coverage at the symposium. 



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