PRESENT STATUS OF THE WHITE-PINE BLISTER RUST, 15 



seems to favor the fruiting of the fungus. Probably the suppression 

 of fruiting bodies in 1911 had something to do with their abundance 

 in 1912. 



A number of European writers have definitely mentioned the time 

 when this fungus fruits upon pines, their dates varying froin March 

 19 to July 7. Very evidently the character of the location and 

 season largely governs the date of fruiting. However, it has been 

 found that this rust fruits earlier than most of the tree rusts. In 

 this country Cronartium rihicola has beeii found in fruit upon pines 

 from early April to early July, the time varying with the earliness of 

 the spring, the warmth of the location, the altitude, and the eleva- 

 tion. Upon comparing this species with native species of Perider- 

 mium of the same district it is found that the white-pine blister rust 

 fruits somewhat earlier than these species of Peridermium. That 

 is, when the latter are in full fruit the white-pine blister rust is already 

 past its maximum season, and if its fruits occur at all they are scat- 

 tering, belated cases. So far as the writer's observations go, this is 

 approximately true of all situations and localities. This may explain 

 why this disease was not observed on pines until 1909, although it 

 must have been in the country in small quantities before that year. 

 One of the most prominent European mycologists ^ has plainly 

 stated that this is decidedly earlier in Europe than other native 

 species of Peridermium. 



DISTANCE SPORES ARE DISTRIBUTED. 



Some observations recently made by the writer ^ upon Cronar- 

 tium comptoniae Arthur are interesting as indicating in a general 

 way the distance that the two hosts of the wliite-pine blister rust 

 must be separated in order to prevent the spread of the fungus 

 from pines to Ribes. In locahties where Pinus rigida Mill, and 

 Oomptonia asplenifolia Gaertner were growing in close proximity 

 to each other it was found in June that the uredo stage of Cronartium 

 comptoniae, wliich was then quite abundant, was present on the latter 

 host within only a few yards (usually within 10 yards) of a diseased 

 pine tree. That is, the secidiospores on pines were apparently blown 

 but short distances from their source. How far occasional spores 

 may be blown is entirely problematical, as no good opportunity has 

 yet been seen for getting evidence along this line. The secidio- 

 spores of Cronartium. comptoniae and of C. rihicola are so similar in 

 size, shape, and general characters that it seems likely that what 

 is true of the mechanical distribution of one will be essentially true 



1 Klebahn. H. Weitere Beobachtringen iiber die niasenroste der Kiefem. Beriehte, Deutsche Botan- 

 ische Cesellschaft, ]U1. G, pp. XLV-LV, 188S. 

 » Spaulding, Parley. Notes on Cronartium comptoniae. Phytopathology, v. 3, no. 1, p. 62, 1913. 



[Cir. 120] 



