8 



BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 



For a number of years Prof. E. Bethel has collected from the leaves 

 of Ribes longiflorum at Denver, Boulder, and elsewhere in Colorado 

 a species of Cronartium which is apparently not identical with the 

 European Cronartium ribicola. The senior writer collected abundant 

 specimens of the uredinial and telial forms of this rust both at Boulder 

 and Denver, Colo., in October, 1914. The telia of this Cronartium 

 are larger, more abundant, and much more conspicuous than those 

 of the European species. Although the fungus has been epidemic 

 for several years on the Chautauqua grounds near Boulder, two young 

 white pines (Pinus strobus) on the grounds not far from the diseased 

 Ribes were free from the disease. This species apparently is able to 

 winter over on Ribes plants in the uredinial form. Itrmay yet be 

 found that the aecial form is a Peridermium on one of our native 



pines. 



DISTRIBUTION OF THE FUNGUS. 



DISTRIBUTION OF THE /ECIAL FORM.* 



The secial form of the fungus, Peridermium pyriforme, is widely 

 distributed in the United States, having been found in 10 States: 



*~r-l / v * "V_ 



**/ 74-jJr r ^ 



FIG. 1. Outline sketch map of the United States, showing the known distribution of Cronartium pyri- 

 forme. Localities where collections of the different forms of the fungus have been made are indicated as 

 follows: v, -3Scial form on species of pines; % uredinial and telial forms on species of Comandra; X, all 

 forms. 



Arizona, California, Colorado, Montana, New Jersey, Pennsylvania, 

 South Dakota, Washington, Wisconsin, and Wyoming (fig. 1); and 

 when a more careful search is made for the fungus, in the light of our 

 present knowledge, it will no doubt be found to have a much more 

 general distribution in this country. It has also been found in 

 Alberta and British Columbia. 



i All specimens cited except those marked with a star (*) have been examined by one of the writers. 



