DANGEROUS INTERNATIONAL FOREST TREE DISEASES 29 



use available information on the cause, hosts, symptoms, distribution, 

 and control of the subject disease or insect. 



Quarantines 



In 1912 the Federal Plant Quarantine Act was enacted in the United 

 States to prevent the importation of plant pests. Under this Act there 

 are prohibitions and limitations regulating the importation of woody 

 plants — seed, seedlings, cuttings, or any plant part — that may result 

 in the entry into the United States of injurious plant diseases and in- 

 sects. The importation of 53 woody genera, including 22 genera of 

 forest trees, is prohibited except as seed or for experimental use under 

 rigid restrictions. No plant pest — "insects, nematodes, bacteria, fungi, 

 other parasitic plants or reproductive parts thereof, viruses, or any 

 similar organisms or infectious substances which can cause disease 

 or damage to plants or plant products" — may be imported from 

 abroad without authorization under a general or specific permit issued 

 by the Department of Agriculture. Under the provisions of this Act, 

 our inspectors, in 1960, intercepted and destroyed about 31,000 poten- 

 tially destructive plant pests, one every 17 minutes. I have no figures 

 on how many of these interceptions were of potential forest pests. 



In 1960 the U.S. Forest Service formally approved two policies of 

 particular interest to this Congress — one with reference to importa- 

 tion and the other to exportation of woody plants or parts thereof. 

 We will import forest trees or other plants into the United States by 

 seed only, subject to postentry fumigation, except in those cases where 

 the plant cannot be reproduced adequately or exactly by seed, as in 

 clonal lines. In such cases, quarantine regulations will be rigidly ob- 

 served. We will export treated seed only as a means of introducing 

 U.S. trees or plants into foreign countries, except in those cases where 

 the plant cannot be reproduced adequately from seed. In such cases, 

 we will inform the importer of the hazards involved and recommend 

 adequate precautions, such as inspection, fumigation, and isolation. 



Exchange of Tree Seed 



The Forest Service cooperates with foreign scientific institutions, 

 universities, and public agencies in the collection and exchange of small 

 quantities of forest tree seeds and other forest plant material for re- 

 search purposes. In 1960, for example, we received 116 requests from 

 39 foreign countries for 603 collections of U.S. forest tree seed. We 

 have filled 337 of these requests and will handle most of the remaining 

 ones in the near future. Also in 1960 we had 19 requests from within 

 the U.S. for 226 collections of foreign forest tree seed, of which 135 

 have been filled. Involved in these exchanges were seed from one to 

 several species of important forest trees in 24 genera. If this rate of 

 exchange of tree seed continues, or increases as it has in the past 

 few years, and the introduced species are established in plantations, it 

 should provide excellent opportunities to determine the susceptibility 

 of many exotic trees to the diseases of other continents. 



In making these exchanges we adhere to the policies on importation 

 and exportation of tree seed as set forth in the preceding section. 



Miscellaneous Activities 



Special surveys and studies are in progress to determine the relat ive 

 susceptibility of native and exotic forest tree species to diseases in the 

 U.S. Among such diseases are white pine blister rust (Cronartium rib- 



