584 BULLETIN 347 
and believe that it is largely responsible for the long-distance jumps 
of the disease. They state: 
“Tt becomes more and more evident as this disease is studied that 
diseased nursery stock is the most important factor in its spread to distant 
points. In that part of the country where it is already well established 
in the native chestnuts its progress is rapid and sure, but there is no 
evidence at present that it is able to pass to remote districts, tens or 
hundreds of miles away, except on diseased nursery stock. Of course 
it is conceivable that the spores are carried by birds. Such distribution 
would, however, follow in general the great lines of bird migration north 
and south and hence would not be an important factor in the western 
spread, except locally. During the summer of 1908 nearly every chestnut 
nursery ‘and orchard of importance in the Atlantic States north of North 
Carolina was visited, and very few were found free from the bark disease. 
Several cases were observed where the disease had obviously spread from 
the nursery to adjacent wild trees.” 
Five prominent cases of spot infections far ahead of the main line of 
advance in western Pennsylvania were traced to nursery trees or scions 
shipped there from infested territory. 
In order to see whether the fungus could be carried on tools that were 
first used on diseased trees and then on healthy ones, thirteen cuts were 
made on healthy trees with an axe after having chopped into diseased 
logs with this ax. Cankers developed later about twelve of these. One 
of the writers performed an experiment of a similar nature, in which a saw 
was first used in sawing diseased wood and then in sawing off healthy 
branches. Cankers were developed about twenty-seven of the fifty 
stubs treated in this way. There is no doubt, then, that the disease 
may be spread by pruning saws, axes, climbers, and other tools used 
about the trees. 
Metcalf (1913) and others have also suggested the possibility of the 
fungus being carried for long distances by the shipping of ties, poles, 
tanbark, and the like. The experiments previously described in treating of 
saprophytic growth show the remarkable ability of the fungus to maintain 
and propagate itself under saprophytic conditions. The writers of this 
bulletin also found that perithecia retain their ability to eject spores 
for at least seven months under perfectly dry conditions. There is no 
reason why the disease cannot start in a new locality to which affected 
logs are shipped, if in that locality the logs are placed near growing chest- 
nut trees. It must be admitted, however, that no case of outbreak of 
the disease in a new locality has ever been traced to the shipment of such 
material. 
