8 BULLETIN 116, U. S. DEPARTMENT OF AGRICULTURE. 



in their wideness of distribution. The fact that 938 trees bearing 

 fruiting bodies of the fungus were found within a certain area is of 

 no special significance unless we note that they were found in about 

 thirty different localities which are scattered well over that entire 

 area of thousands of square miles. Then we perceive that it is 

 inevitable that the disease will become established in one or more of 

 those localities unless efficient control measures are taken and faith- 

 fully continued until the disease is eradicated . As already indicated, 

 this is not being done everywhere. 



TABLE II. Results of inspection^ of 80 lots of infected white-pine trees. 



Items 1 and 2 show that in one-fifth of the lots the inspector appar- 

 ently removed all the trees bearing fruiting bodies of the fungus in a 

 single year, but in every such case trees were found thereafter which 

 were diseased, but did not bear the spores of the fungus. In a single 

 instance only, all of the diseased trees were apparently removed by the 

 first inspection. Our experience to date decidedly discourages the 

 idea that a single inspection is efficient in eradicating this disease. 

 Item 5 apparently contradicts this statement, but these lots may 

 easily have been cases where the inspector took everything showing 

 any abnormality and reported it as suspicious, when the disease was 

 really absent. 



In a previous paper * the writer mentioned the apparent effect of 

 cool weather in regulating the formation of telia of Cronartium ribicola 

 in the greenhouse at Washington. This experience has been repeated 

 the present season. Apparently, farther north, where the nights are 

 relatively cool, this inhibition does not occur, as tclia were found in 

 northern Vermont on July 23. 



In a recent publication, 2 which received limited distribution, the 

 writer showed the inefficiency of inspection, except as a temporary 

 expedient, in trying to eradicate this disease. The total destruction 

 of infected lots of white pines was urged as being the only safe course. 

 This means a considerable present loss, which, however, will be very 

 slight when compared with the loss that will result if the blister rust 

 is allowed to become established and to spread. 



1 Spaulding, Perley. Notes upon Cronartium ribicola. In Science, n. s., v. 35, no. 891, p. 146-147. 1912. 

 * Spaulding, Perley. The present status of the white-pine blister rust. In U. S. Dept. Agr., Bur. Plant 

 Indus. Circ. 129, p. 9-20, 6 fig. 1913. 



O 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914 



