2 



may be exi)ecled lo be more or less abundant in any locality. There 

 are a few isolated infections beyond this line in the western half of 

 the State. 



THE LOSS 



If we take into consideration only the commercial value of the 

 timber products and nuts, it is safe to say that the blight has already 

 caused a loss of |7,(H)0,000 in this State. If we consider the value 

 of the chestnut as a lawn and park tree and the value which such 

 trees give to real estaie, the financial loss is certainly not less than 

 13,000,000 more than that mentioned above. Yet this estimated 

 loss of ten millions of dollars in Pennsylvania is small when com- 

 pared with that which may occur throughout the entire country. 

 Dr. Haven Metcalf, U. S. Department of Agriculture, estimates the 

 present total loss caused by the disease as not less than twenty-five 

 million dollars, (125,000,000^. The rapid progress of the blight 

 through Pennsylvania and Maryland threatens the complete commer- 

 cial extermination of the chestnut, unless the disease is conquered 

 in a very short time. Few persons in oastern Pennsylvania realize 

 how rapid has been the progress of the blight, but to be convinced 

 •f this fact, it is only necessary for one to become familiar with this 

 disease and to closely examine the woods. 



THE CAUSE 



Many cases of su])posed chestnut blight when investigated prove 

 to be dead or unhealthy trees that have sulTc.red from insect attack, 

 lightning, or other common injuries. The real chestnut blight, more 

 properly known as the chestnut bark disease, or the chestnut canker 

 disease, is caused by a fungus, and is not, as snme erroneously believe, 

 the work of an insect. It affects, in varying degrees, all kinds of 

 chestnuts, but pure strains of the Japanese chestnut have the power 

 of resisting the disease to a remarkable extent. The chinquapin is 

 killed by it, but, so far as is now known, living oaks and other trees 

 are not attacked by this fungus, although it has been found on dead 

 oaks and also on dead sumach. 



THE BLIGHT 



This fungus is a parasitic plant which resembles in many ways the 

 moulds that form on decaying food. It grows however, in the inte- 

 rior of the bark and not on its surface, and feeds cm living tissues 

 instead of wholly on dead material, as do the moulds mentioned. It 

 may be described as consisting of great numbers of tiny threads, 

 which branch and grow in every direction through the bark. These 

 threads, collectively known as the mycelium, are so small that a single 

 one can be plainly seen only through a microscope; but they are so 



