6 BULLETIN 116,. TJ. S. DEPARTMENT OP AGRICULTURE. 



more dangerous than are the native wild plants, because many white- 

 pine plantations are made on deserted farms. In such places the 

 former garden currants persist for years, and the inspector often 

 finds them in the midst of a plantation of imported pines. Moreover, 

 nurserymen often keep stocks of white pines and Ribes in proximity 

 to each other, which is dangerous if either has the disease. These 

 facts do not mean that wild species of Ribes can be disregarded, but 

 that both wild and cultivated species must be considered when con- 

 trol measures are undertaken. 



PINUS EXCELSA A HOST. 



In a recent publication Lind 1 mentions the Himalayan pine (Pinus 

 excelsa) as a known host of the white-pine blister rust in Denmark. 

 The writer is informed that the disease was found in 1913 upon 

 young trees of Pinus excelsa in Massachusetts. Unfortunately, no 

 specimens of it were saved, but there seems to be no doubt that 

 Pinus excelsa is a host of this fungus and is liable to be affected by it 

 in this country. This is the first time that the white-pine blister 

 rust has been found here on any other species of pine than Pinus 

 strobus. 



AGE OF DISEASED WHITE-PINE TREES. 



White-pine trees from 3 to about 75 years old having the blister 

 rust have been seen. From 3 to 15 years the series was almost unin- 

 terrupted; then the ages were approximately 18, 20, 25, and 75 

 years. The trees of 25 and 75 years were diseased on the branches 

 and not on the main stem, but below 25 nearly all have been affected 

 on the main stem. The evidence seems to show that this disease 

 has been present on small numbers of imported pine trees in this 

 country since 1888, and perhaps longer. 2 



DISTRD3UTION OF SPORES OF CRONARTIUM RIBICOLA. 



In 1912 the writer made some observations on the distribution of 

 the spores of Cronartium comptoniae from Pinus rigida to Comptonia 

 asplenfolia. 3 The seciospores are so similar in size and shape to those 

 of the blister rust on white pine that it seems probable that one would 

 be distributed as far as the other under the same conditions. It was 

 found that the seciospores of Cronartium comptoniae were blown 

 about 30 feet from their point of origin. This led the writer to sus- 

 pect that the seciospores of the white-pine blister rust would also be 

 blown relatively short distances. Such has been the case in all those 



^ind, Jens. Danish fungi as represented in the herbarium of E. Rostrup, p. 281-2S3. Copenhagen, 

 1913. 



2 Spaulding, Perley. The blister rust of white pine. U. S. Dept. Agr., Bur. Plant Indus. Bui. 206, 

 p. 36. 1911. 



3 Spaulding, Perley. Notes on Cronartium comptoniae. In Phytopathology, v. 3, no. 1, p. 62. 1913. 



