374 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



THE WHITE-PINE BLISTER RUST. 



The white-pine blister rust, a most destructive disease affecting 

 five-leafed pines, was the subject of the first quarantine issued under 

 the authority of the plant quarantine act. This quarantine pro- 

 hibited the entry of certain pines from certain countries in Europe. 

 The increased knowledge of the foreign distribution of this disease 

 made it necessary to revise this quarantine and it was reissued as 

 Quarantine No. 7, May 21, 1913, forbidding the importation into 

 the United States of all five-leafed pines from every country of 

 Europe and Asia. Prior to this quarantine action this disease had 

 gained foothold in New 7 Hampshire, Vermont, Massachusetts, Con- 

 necticut, New York, Pennsylvania, New Jersey, Ohio, and Indiana, 

 and it is now known to occur in all of these States except Ohio, 

 Indiana, and New Jersey. In the meantime it had also obtained 

 considerable foothold in Canada. 



The States invaded by the white-pine blister rust have been 

 actively engaged for several years, in cooperation with this depart- 

 ment, in an endeavor to stamp out the disease, and this action has 

 apparently been successful in the three States last named. The 

 occurrence of this disease in Canada and the fact that its alternate 

 host includes the genera Ribes and Grossularia necessitated an 

 amendment to Quarantine Notice No. 7. This amendment was 

 promulgated February 29, 1916, forbidding the importation into the 

 United States from the Dominion of Canada and Newfoundland of all 

 five-leafed pines and of all species and varieties of Ribes and Grossularia. 



At the request of the State forester of New York an informal 

 conference was held by the Federal Horticultural Board July 20 

 with various other State foresters and State nursery inspectors to 

 discuss the white-pine blister rust situation in the United States. 

 The object of the conference was to hear the latest reports on the 

 distribution of the disease and to discuss methods of concerted 

 action by the States and the United States Department of Agriculture 

 in the eradication of this disease. 



It developed that the white-pine blister rust was more widespread 

 in the East than had been realized, and it was feared that unless some 

 regulatory action was taken the disease would get beyond control. A 

 public hearing was accordingly held February 4, 1916, to determine 

 the best means of preventing further spread of this disease in this 

 country. Following the hearing, as already noted, a prohibition was 

 placed on the impoitation of all five-leaf eel pines and all species and 

 varieties of the genera Ribes and Grossularia from the Dominion 

 of Canada and Newfoundland. 



In view of the known wide shipments of supposedly diseased five- 

 leafed pines from Germany, prior to the establishment of the original 

 quarantine in 1912, it was realized that there was a strong probability 

 that the white-pine blister rust is much more widely distributed in the 

 Mississippi Valley States than has been so far disclosed by inspection. 

 This point of view has since been confirmed by the finding of infections 

 in Wisconsin and Minnesota. The uncertainty as to the distribution 

 of the disease in the United States made it impracticable to take any 

 quarantine action until a thoroughgoing field survey had been 

 made. Such a field survey the Bureau of Plant Industry agreed 

 to undertake at once in cooperation with the board, and this survey 

 is now in progress. 



