[Cir. 129— B] 



THE PRESENT STATUS OF THE WHITE-PINE BLISTER RUST/ 



By Perley Spaulding, Pathologist, Investigations in Forest Pathology. 



INTRODUCTION. 



Since the publication in 1911 of Bulletin No. 206 of the Bureau of 

 Plant Industry, entitled ''The Blister Rust of White Pine/'consid- 

 erable new information has been obtained concerning the blister rust 

 and the fungus that causes it. This is of such a nature that it is 

 thought best to publish it at once, so that the various persons who 

 have to deal with the disease may have the fullest information pos- 

 sible with which to carry on their work. 



FIELD CHARACTERS OF THE DISEASE. 



In previous publications upon this subject- the writer has described 

 those symptoms of the disease that seem to be distinctive and that 

 are evident without the use of a microscope, that is, the "field char- 

 acters" by which inspectors must recognize it. Those symptoms 

 which were first recognized follow: (1) The presence of the fruiting 

 bodies of the fungus and the cavities in the bark where they have 

 been recently borne, (2) the stunted growth and compact appearance 

 of the tops of badly diseased trees 3 to 5 years old, (3) the roughened, 

 scaly bark on stems which bore fruiting bodies in previous years (see 

 fig. 1 for healthy stem), (4) the abnormal swelling of affected stems 

 of trees usually less than 6 years old, and (5), rarely, the local dying 

 of the bark more or less completely around the young stem of trees 

 3 or 4 years old. Later an additional and more uncommon symp- 

 tom was described by the writer,'' namely, a coarse yellow mottling 

 of the leaves and bark on the affected portion of trees which have 

 shown the disease the previous year and which are about to die. 

 This symptom has been mentioned by Klebahn* as occurring upon the 

 needles of trees artificially inoculated with teleutospores of the fungus; 



1 Issued June 7, 1913. 



2 Spaulding, Perley. 



(a) European currant nist on the white pine in America. U. S. Department of Agriculluro, Bureau 

 of Plant Industry, Circular 3.s, 4 p., 1909. 



(h) Peridermium Strobi Klebahn in .America. Science, u. s., v. 30, no. 763, p. 200-201, 1909. 

 ^Spaulding, Perley. Notes upon Cronartium ribicola. Science, n. s., v. 35, no. 891, p. 14(5-147, 1912. 

 4 Klebahn, H. Kulturvorsuche mit Rostpilzen. XII. Bericht (1903 imd 1904). Zeitschrifl fiir rnnu- 

 zenlcrankhciten, Hd. 15, Heft 2, p. S7, 1905. 



94553°— Cir. 129—13 2 9 



