pflOPCffTr OF/m IVI9ION 



UNITED STATES DEPARTMENT OF 



FARMERS 

 BULLETIN 



R 



CULTU 

 FORNT 



WASHINGTON, D. C. 



742 



JUNE 9, 1916 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 



THE WHITE-PINE BLISTER RUST. 1 



BY PERLEY SPAULDING. Pathologist, Office of Investigations in Forest Pathology. 



CONTENTS. 



Introduction 1 



What to do about white-pine blister rust 



What to do about white pines already 



planted 



How to buy white-pine stock free from 



blister rust 



Danger from the white-pine blister rust 



Page. 



Appearance of the disease 9 



Life history of the parasite 11 



Efforts already made to control the white- 



, pine blister rust '. 14 



Present status of the white-pine blister rust. . 15 



Need for adequate State laws 15 



INTRODUCTION. 



The white-pine blister rust is a destructive disease of the so-called 

 white pines, that is, pines which bear their needles in bundles of five 

 each. It has caused much damage in some of the countries of north- 

 ern Europe. It is caused by a parasitic fungus (a plant organism) 

 similar in many respects to the fungi that cause wheat rust and cedar 

 apple rust. Like those diseases, it requires two distinct kinds of host 

 plants in order to complete its entire Ufe. These are (1) the 5-needle 

 pines and (2) the wild and cultivated currants and gooseberries. 



This serious disease of our white pines came to us from Europe in 

 imported white-pine seedlings. It is now known that comparatively 

 small lots of such diseased seedlings were imported as long ago as 

 1900, or even earlier; but in the year 1909 immense numbers of such 

 seedlings were brought into the country and were largely distributed 

 before the presence of the disease was discovered. In this way the 



i This publication is designed to be spread open at the colored plate, so as to serve as a poster when desired. 

 39806 Bull. 742-16 



