6 CONNECTICUT EXPERIMENT STATION, BULLETIN NO. 178. 



is the best course to pursue under the particular conditions in 

 which his woodlot is situated. 



CAUSE OF DISEASE. 



First of all, let it be clearly understood that the chestnut blight 

 is caused by a fungus and not by an insect, as is often erroneously 

 supposed. The fact that insects of various kinds are found in 

 the dead bark of an affected tree has often led to the conclusion 

 that the trouble is of insect origin, but such is not the case and 

 insects have no part in causing cffestnut blight. 



DESCRIPTION. 



The chestnut disease is caused by the fungus technically known 

 as Endothia gyrosa var. parasitica. This fungous parasite pene- 



FIG. II. BLIGHT STARTED THROUGH INSECT INJURY (A), AND PRUNED BRANCH (B); 

 C. MATURE FRUITING PUSTULES ON SMOOTH BARK. 



