PRESENT STATUS OF THE WHITE-PINE BLISTER RUST. 



13 



trees had hundreds of distmct spore bodies. There was no (^-idence of 

 these trees having been infected since reachmg this country. The 

 affected area was just below the lower branches, where it nearly always 

 is found in newly imported trees bearmg fruiting bodies of the fungus 

 when received at the port of entry. These trees had not borne fruit- 

 ing bodies in previous years, since the bark of the affected area was not 

 scaly, as it is where fruiting bodies have previously been produced, 

 and, furthermore, since all visibly diseased trees 

 had been destroyed in previous years. So far as 

 could be ascertamed the disease had lain dormant 

 for five years in these trees, only to break out with 

 the most profuse production of fruiting bodies yet 

 seen in this country. 



In 1909 ^ the writer concluded, from data af- 

 forded by numerous papers of European writers 

 (which was the only available information), that 

 inspection of diseased plantations for a few years 

 might result in the fhial eradication of the dis- 

 ease, and this procedure was recommended rather 

 than the more drastic one of total destruction of 

 infected plantations. Smce that time personal 

 mvestigations, such as above described, have in- 

 dicated that this ])rocedure is not proving as 

 effective as desired. 



In the light of the above results it seems best 

 to recommend the total removal and destruction 

 of diseased plantations wherever possible. It is 

 recognized that there are diseased plantations 

 which it may be impossible to destroy, but these 

 are few m number. Mere unwillmgness or tem- 

 porary mexpediency should not be substituted 

 for impossibility in considermg this matter. This 

 does not necessarily mean that every plantation 

 must be destroyed ui a smgle year. The values 

 involved and the number of trees are so large that 

 it would be unwise for those States which have the larirest numbers to 

 undertake to replace all the diseased plantations m one year. It is 

 believed that the removal of diseased plantations can be done gradu- 

 ally, those which are worst bemg taken first. It should especially 

 be done where Ribes occurs in the vicinity of the diseased plantations. 

 Much danger would thus be eUminated. In manv cases the cost of 



Fig. 5.— a 5-year-old white- 

 pine tree, sliowiiig scaly 

 bark caused by the blister 

 rust. 



1 Spaulding, Parley, 

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

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



(6) Peridermium Strobi Klebahn in America. Science, n. s., v. 30, no. 7fi3, p. 2()l)-2()l, 1909. 

 (c) Notes upon Cronartium ribicola. Science, n. s., v. 35, no. S9I, p. 146-147, 1912. 

 ICir. 129] 



