1064 JOURNAL OF FORESTRY 



the disease is worse in northern than in southern Europe. This may possibly 

 indicate that the disease is apt to prove particularly destructive in the northern 

 United States and Canada, where the white pine attains its best development. 



2. The rust is strictly a parasite, and from such evidence as is available it 

 appears probable that the disease is more virulent on healthy, vigorous-growing 

 trees than on weaker ones. This would seem to disprove the theory advanced 

 by some, that the ravages already caused by the disease are due primarily to the 

 poor silvicultural condition of white pine in the Northeast, and that if the silvicul- 

 tural condition of the stands were improved and nursery stock grown only from 

 good seed from vigorous trees the danger would be practically negligible. 



3. Positive prorf that the blister rust over-winters on Ribes bushes has not yet 

 been obtained, but circumstantial evidence points to this being the case. The 

 experiments will be continued in the hope of securing indisputable evidence on 

 this point. Evidence has also been obtained that the spores are apt to over- 

 winter on the pine brush resulting from felled trees if the needles stay green all 

 winter. This apparently furnishes an additional argument for brush disposal in 

 the case of pine stands affected by the disease. 



4. Wind is probably the main agent in bringing about the distribution of the 

 disease, although it has been proved that it is also distributed to a certain extent 

 by birds and insects. 



5. Exact evidence has not yet been obtained as to the width of the strip sur- 

 rounding any given stand of white pine which must be cleared of Ribes in order 

 to remove the danger of serious infection. After considerable discussion a reso- 

 lution was adopted stating that, in the opinion of the committee, in view of the 

 evidence so far available, pine stands themselves free from Ribes are not in 

 danger of serious infection from a commercial standpoint, provided Ribes is 

 eradicated from a zone one-third of a mile in width surrounding the pine stand. 

 This distance is, of course, subject to revision on the basis of further investiga- 

 tion. 



6. It was the consensus of opinion that the disease is now so firmly established 

 in New England and New York, probably also in Ontario, as to make its eradica- 

 tion out of the question. In these regions, therefore, it is now a question for 

 each individual owner to decide what measures, if any, he desires to take for the 

 protection of his white-pine stands. The character of the work undertaken by 

 the Office of Forest Pathology in this region will hereafter probably be confined 

 mainly to experiments to determine the best means of control and to experimental 

 demonstrations in a few places on a comparatively large scale. 



In the Lake States the disease is now more widely distributed than it was a 

 year ago, particularly in the valley of the St. Croix River, but hope of eradicating 

 it in this region has not yet been abandoned. Here the work of the Office of 

 Forest Pathology will probably continue along the old lines of scouting and 

 control measures. 



No evidence has yet been found to indicate that the disease has obtained a foot- 

 hold in either the white-pine or sugar-pine region. 



7. The committee seemed to be uniformly of the opinion that the white pine 

 is a sufficiently valuable crop to justify control measures, and that the work of 

 eradication and control should be vigorously continued. The adoption of correct 

 silvicultural practice in the handling of white-pine stands was urged as one 

 means of control that should receive more attention than heretofore. The com- 

 mittee adopted a resolution urging the Federal Government to continue its present 

 appropriation for fighting the disease. 



8. A resolution was adopted urging Congress to pass a law prohibiting the 

 importation of nursery stock as defined by the Plant Quarantine Act of 1912, 

 with the provision that the Department of Agriculture might arrange for the 

 importation and distribution of any plant material that appeared to be ot value 

 for use in this countrv. The wording of the resolution as adopted would not 

 prohibit the importation of forest-tree seeds under the same conditions as at 

 present. 



The secretary of the committee was requested, if practicable, to make 

 arrangements for printing the proceedings of the conference in con- 



