8 CONNECTICUT EXPERIMENT STATION, BULLETIN NO. 178. 



cable except perhaps on single trees used for ornamental pur- 

 poses. 



Medication. Injecting various substances into the tree has 

 been tried but with no success, as any substance sufficiently 

 poisonous to kill the blight is injurious to the tree, and further- 

 more it is difficult to make a tree absorb any very great amount 

 of material injected into it. 



Cutting Infected Trees. The removing of all infected trees 

 has been tried but as with the other remedies its success has 

 been only indifferent at the best, as it is hard to find all infected 

 trees when scouting for the disease, and the few not found are 

 sources of new infections. The expense and trouble of destroy- 

 ing infected portions of the tree after cutting makes this method 

 of control out of the question for treating chestnut woodland. 



Thus at present we are without any effective method of com- 

 bating this trouble in the forest and at best are only partly 

 successful with single specimens in a yard or park. 



DISSEMINATION OF SPORES. 



There are several ways in which the blight may be. spread, but 

 from our own observations it would seem that the wind and 

 possibly birds, especially those which hunt for larvae of insects 

 in the bark, are chiefly responsible. It can be readily seen that 

 when an affected tree is producing countless millions of such 

 minute spores the wind will easily blow them to a considerable 

 distance. This is especially true of the winter spores, which are 

 forcibly ejected from the sacs in which they are borne. These 

 spores lodging in a wound in the bark of a chestnut tree or 

 being washed there by the rain would start a new infection of 

 the disease. As the summer spores are produced in sticky 

 masses, birds may pick them up on their beaks and feet and 

 thus carry them to new localities. Other ways of dissemination 

 are insects and transportation of diseased chestnut wood from 

 one place to another. The fungus often produces spores for one 

 or two years on cut wood especially when the bark has been 

 left, so that diseased wood can be a source of infection for 



