86 BULLETIN" 967^ U. S. DEPARTMENT OF AGRICULTURE. 



The experiments in the removal of Ribes on an extensive scale 

 have gone far enough to prove that it is a practical method of pro- 

 tecting pine stands. Accordingly the public has been urged to des- 

 troy wild and cultivated Kibes within at least 200 yards of valuable 

 pine stands in the generally infected regions. 



Assistance to individual pine owners, towns, and associations in j)rotecting pine 

 areas from the blister rust is given by the New England States, New York, Wisconsin, 

 and Minnesota, in cooperation with the United States Department of Agriculture. 

 In 1919, about $10,000 was subscribed for cooperative eradication of currants and goose- 

 berries by indi^dduals and associations in New York. In I^Iassachusetts, local coop- 

 erators furnished $1,075. In New Hampshire, 53 towns voted appropriations totaling 

 $8,514, and 34 individuals and firms sixbscribed $2,053 additional. The interest of the 

 public in blister-rust control is further evidenced by the fact that this State destroyed 

 21,171 bushes of cultivated currants and gooseberries belonging to 1,023 owners, and 

 only 3 owners insisted on compensation for their bushes (24). 



The State and Federal authorities favor cooperation with towns, 

 counties, associations, or groups of individuals in order to free from 

 Ribes as large an area as possible in each locality. This reduces cost 

 per acre and increases the effectiveness of the protection to pines. 



SCREENING RIBES AND PINES WITH OTHER SPECIES. 



Screens of heavy underbrush or trees surrounding or covering 

 Ribes will do much to prevent infection of the Ribes by seciospores 

 and will greatly reduce infection of white pines, if the Ribes do be- 

 come infected (145, 146). 



Screens or windbreaks of other kinds of trees around the edge of 

 white-pine stands will greatly reduce infection on the pines. In the 

 same way, planting in mixture or in strips alternating with another 

 species should help to keep the disease down. 



SELECTION OF SITES FOR PINES. 



Infection by Cronartium ribicola may be reduced to a minimum in a 

 generally infected area by judiciously choosing a site for the planting 

 or natural seeding of white pines. Areas where there is a minimum 

 number of Ribes, or where they have been eradicated, which are not 

 in moist locations and are not especially subject to fogs or mists, and 

 which are protected by forests or conformations of the land from 

 heavy sweeping winds, are favorable for the encouragement of the 

 growth of white pines. The converse conditions are to be avoided 

 as far as possible. 



SPRAYING. 



Spraying has been little used in North America to control the white- 

 pine blister rust, as the chances for success have appeared to be 

 slight. Spraying of Ribes to prevent their infection has been tested 

 in a number of instances. 



In 1915,McCubbui (86) carried on some careful spraying tests with 

 Ribes nigrum plants, using both Bordeaux mixture and soluble sul- 



