4 . CHESTNUT TREE BLIGHT. 
nursery stock may carry the disease bodily for great distances. The 
an of infeciona take place throug wounds made by bark- 
borers. The relation of insects to the disease appears to be very 
intimate. ; ‘ ; 
(5) The origin of the disease is unknown. Its obvious spread 
from a center—the vicinity of New York City—suggests that it is 
not a native disease; and the resistance of Asiatic species of chestnut 
to the disease suggests that it may have been imported from Asia 
with the Japanese chestnut. No evidence has been secured to 
connect the considerable losses of chestnut timber in the Southeastern 
States in past years with this disease; these losses were more probably 
due to attacks of insects. ; oy lac! 
(6) The disease was first called to public attention in 1904, but 
it probably had already been present on Long Island for some years. 
(7) The value of the chestnut stand is variously estimated at 
between three hundred and four hundred million dollars. This 
disease has already caused an estimated minimum damage of 
$25,000,000. ; 
(8) Judging by the history of the disease to date, it may be expected 
to spread throughout the range of the chestnut tree during the next 
two years, unless checked by human effort. Whatever is done to 
control the disease by any methods known at present must be 
attempted immediately, else the disease will be beyond control by 
any effort ever likely to be put forth. 
(9) As shown on the accompanying map (PI. I), the disease is now 
known to occur in at least 10 States, viz: Massachusetts, Rhode Island, 
Connecticut, New York, New Jersey, Pennsylvania, Delaware, Mary- 
land, West Virginia, and Virginia. In all of Connecticut, New Jersey, 
and Delaware, and in western Massachusetts, eastern New York, 
eastern Pennsylvania, and northeastern Maryland, the chestnut trees 
are already generally infected, and a large per cent are already dead. 
(10) Outside of this area of general infection the disease occurs at 
scattered points (‘‘advance infections’’). These consist mostly of 
single infected trees, or small groups of trees, often many miles apart. 
(11) Analogy with pear blight and peach yellows aa with animal 
and human diseases that are controlled by destruction or isolation of 
the foci of infection suggests early destruction of the advance infec- 
tions as the only possible means of controlling the disease or limiting 
its range. There is no contagious disease known that does not yield 
to sanitation and quarantine. The destruction of diseased trees can 
not possibly be an effective means of control, however, in localities 
where the disease has already become general. 
This method of destroying advance infections has been employed 
extensively b hig owners to check the progress of the disease 
in their own holdings. But since general cooperation is necessary 
to make any sanitation finally effective, it appears necessary to 
organize private effort under State control. This has already been 
done in Pennsylvania under special law, and is about to be done in 
Virginia under special law; and under the general laws now existing, 
in West Virginia and probably some other States. This department 
indorses the work of these States, and particularly the early and 
vigorous action of Pennsylvania. ; 
(12) Results to date indicate the following lines of activity as 
desirable and necessary to be carried out by this department and 
the various States in cooperation: 
