SAFEGUARDING THE WHITE PINE CROP 



BY SAMUEL B. DETWILER 



WHITE pine can be protected from serious damage 

 by the blister rust, but action must be prompt. 

 This is the substance of the conclusions reached 

 by the Sixth Annual International Blister Rust Confer- 

 ence recently held in Boston, Massachusetts, under the 

 auspices of the American Plant Pest Committee. Experi- 

 ments begun in 191 6 demonstrate that this disease is 

 effectively controlled local- 

 ly by destroying wild and 

 cultivated currant and 

 gooseberry bushes within 

 200 to 300 yards of the 

 pine. Local control is prac- 

 ticable because the spores 

 which cause the infection 

 in the pines are very deli- 

 cate, living only ten min- 

 utes or less, even under 

 favorable conditions. Sim- 

 ple methods of field work 

 have been developed which 

 insure destruction of over 

 95 per cent of the wild cur- 

 rant and gooseberry bushes, 

 which abound in white pine 

 regions. The cost of con- 

 trol work averaged only 35 

 cents per acre on more than 

 a quarter million acres cov- 

 ered in 1920. East of the 

 Great Plains, the disease is 

 permanently established and 

 spreading rapidly, but any 

 body of white pine may be 

 protected locally, at mod- 

 erate cost. The white pine 

 blister rust has not been 

 found in the far West. 

 The hope of saving the 

 western white pine forests 

 from infection lies in strict 

 enforcement of the Federal 

 and State quarantines. 



The conference was well 

 attended and great interest 

 was shown in the many 

 phases of control work. 

 All of the New England 

 States, New York, New 



Jersey, Wisconsin, and Minnesota were represented of- 

 ficially, as well as the United States Department of 

 Agriculture. Representatives of a number of forestry 

 and plant pathological organizations in the United States 

 and Canada also took part. The conference opened with 

 brief reports by the State and Federal officials on the 



WHITE PINE BLISTER RUST CANKER ON A TRUNK SIX INCHES 

 IN DIAMETER 



White pine blister rust is caused by a parasitic fungus imported from 

 Europe twenty years ago. In 1915 and 1916, it was discovered to be 

 widely distributed in New England and northeastern New York, with 

 spot infections in Minnesota, Wisconsin, Ontario and Quebec. Since 

 1916, experimental control on a large scale has been carried on in the 

 New England States, New York, Wisconsin and Minnesota, in close 

 co-operation with the United States Department of Agriculture. Con- 

 trol of the blister rust is possible because the disease does not advance 

 directly from one pine to another. It must pass through a period of 

 development on the leaves of currants or gooseberries (Ribes) before 

 it can harm healthy pines. Therefore, the essential feature tn control 

 work is to destroy wild and cultivated currant and gooseberry bushes 

 adjacent to the pines. 



progress of co-operative control work. Results of scout- 

 ing for the blister rust in thirty-three States, and control 

 work in nine States, were summarized. This was fol- 

 lowed by reports on pathological investigations of the 

 disease by Dr. H. H. York, Dr. L. H. Pennington, 

 Dr. Perley Spaulding, Dr. G. P. Clinton, Dr. Walter 

 H. Snell, and Dr. Haven Metcalf. The remainder of the 



program dealt with various 

 aspects of local control of 

 the disease in infected re- 

 gions, including a resume 

 of experimental work con- 

 ducted by the Office of 

 Blister Rust Control, 

 United States Department 

 of Agriculture, and papers 

 embodying constru c t i v e 

 suggestions on the many 

 details of the practical 

 field work. 



As a result of five sea- 

 sons' experimental work, it 

 was shown conclusively 

 that the removal of cur- 

 rant and gooseberry bushes 

 from the vicinity of pine 

 stands effectively controls 

 the blister rust. The proof 

 of this fact is among the 

 most important data pre- 

 sented to the conference. 

 This report was made by 

 Dr. William E. Pickler and 

 Mr. L. W. Hodgkins, of 

 the Office of Blister Rust 

 Control, as a result of re- 

 inspection of the control 

 area at Lenox, Massachu- 

 setts. 



In 1916, currant and 

 gooseberry bushes were 

 uprooted extensively in the 

 vicinity of Lenox, Massa- 

 chusetts. This was the first 

 attempt at local control of 

 the blister rust by eliminat- 

 ing all of these secondary 

 hosts of the blister rust 

 from a large territory. Con- 

 sequently, the workers lacked training and experience, 

 and the work resulted in the removal of not more than 

 70 to 80 per cent of the wild currant and gooseberry 

 bushes. Since 1916, this work has been standardized so 

 that an average efficiency of 95 per cent of the wild 

 currants and gooseberries are destroyed in once going 



