88 JOURNAL OF FORI'STRV 



although infection is complete in the immediate vicinity of oldest infec- 

 tion. 



5. Still more hopeful for the continued growing of white pine is the 

 fact that in areas where the disease is generally prevalent local control 

 measures can be inaugurated at any future time by the elimination of 

 Ribes. For example, if in a given area it should not be practicable at 

 the present time to attempt the eradication of Ribes, and the disease 

 should become established there ; if at some future time the increasing 

 value of white-pine stumpage or other considerations should make the 

 removal of Ribes practicable, the work could be undertaken and plant- 

 ing and normal reproduction developed, since the disease already pres- 

 ent upon white-pine trees would not spread to other white pines in the 

 absence of the intermediary host. 



On the other hand, there are certain considerations which are un- 

 favorable for the control of the disease. The first of these is the poten- 

 tial western spread of the disease across New York and westward from 

 Ontario. It does not seem practicable under our political and social 

 system to carry out the immune-zone idea in order to block any large 

 movement of any disease or pest, and, this being the case, it is necessary 

 to calculate the time element in the western spread of the disease in 

 figuring the value of eradication of advance infections. The other con- 

 siderations opposed to control of the disease are temporary, but none 

 the less serious. Both countries concerned are at war, and in conse- 

 quence help is scarce, particularly the temporary help for the growing 

 season which is required in this work. During the present season we 

 have experienced the greatest difficulty in securing men at a reasonable 

 price for the work and holding them. We have been compelled in many 

 cases to employ inferior men. Many have enlisted, many have been 

 drafted, and not a few have resigned to accept more lucrative or more 

 permanent employment in industrial lines. We may expect that for the 

 period of the war this condition will grow worse instead of better. 



I judge from the discussion which we have had that we are all agreed 

 that our policy for another year must be as follows : 



To continue west of the Mississippi River the same program, of scout- 

 ing and tracing suspicious nursery stock that has been carried on during 

 the past year. In the area from the Mississippi River to the Hudson 

 River, to continue the eradication of advance infections and follow up 

 nursery stock in the areas not now known to be infected. East of the 

 Hudson River, however, our' policy must be that of purely local control, 

 which must be undertaken in favorable localities of various types on an 



