CHESTNUT BARK DISEASE. 443 



bark disease, in those regions or states where it has not yet 

 obtained a serious foothold, by means of quarantine and cutting 

 out all diseased trees. This recommendation was based on the 

 results of some experiments carried on in the vicinity of Wash- 

 ington, D. C, concerning which they write as follows: 



"Fortunately, however, there is a method of dealing with the 

 situation which is applicable to the country as a whole and 

 which, so far as tested, is practicable. Early in the course of 

 the writers' investigations it became evident that the disease 

 advances but slowly in a solid line, but instead spreads from 

 isolated centers of infection often many miles in advance of 

 the 4nain line of disease. * * * It therefore seems probable 

 that if these advance infections could be located at a reasonably 

 early stage, they could be eliminated at relatively little expense, 

 thus preventing further spread from these points, at least. 

 Accordingly the country within approximately thirty-five miles of 

 Washington, D. C., was chosen in the fall of 1908 as preliminary 

 territory in which to test this method of control. This section 

 has been gone over fairly thoroughly once a year. As will be 

 shown by Figure i, fourteen points of infection were located 

 and the infected trees destroyed. Most of this work was done 

 by the senior writer. The largest infection was a group of 

 nursery trees that had been imported from New Jersey; the 

 smallest, a simple lesion on a small branch of a large forest 

 tree. In one case eleven forest trees in a group were infected, 

 the original infection having been on two trees dating apparently 

 from as early as 1907. Up to the present time (June, 1911) 

 the disease has not reappeared at any point where eliminated, 

 and the country within a radius of approximately thirty-five 

 miles from Washington is apparently free from the bark disease, 

 although new infections must be looked for as long as the 

 disease remains elsewhere unchecked. It is therefore believed 

 that this method of attack will prove equally practicable in other 

 localities, and if carried out on a large scale, will result ultimately 

 in the control of the bark disease." 



Stewart, of the Geneva, N. Y., Station, and the writer, through 

 the kindness of Metcalf, had the opportunity of examining, in 

 January, 1912, part of the region where this work was carried 

 on. Stewart (70) in his paper at Harrisburg said: "I hold 

 that no definite conclusions can be drawn from that test." The 



