A DEADLY FUNGUS ON THE AMERICAN 

 CHESTNUT. 



By HERMANN W. MERKEL, 



CHIEF FORESTER AND CONSTRUCTOR. 



DURING the past year an epidemic of a fungus disease has 

 occurred throughout the parks of this Borough, which, but 

 for the fact that it was confined to a single species of tree, might 

 have overshadowed in deadhness and rapid spread all the other 

 enemies of tree life. 



This disease was first noticed in the New York Zoological 

 Park, in a few scattered cases which occurred during the summer 

 of 1904. Since that time, however, it has spread to such an ex- 

 tent that to-day it is no exaggeration to say that 98 per cent of 

 all the chestnut trees in the parks of this Borough are infected. 

 The spread of this disease is so sudden that unless some radical 

 measures are taken, or a natural enemy of this fungus develops, 

 it is safe to predict that not a live specimen of the American 

 Chestnut {Castanea dentata) will be found two years hence in 

 the neighborhood of the Zoological Park. 



This fungus attacks the live and apparently sound bark of 

 twigs, branches, and limbs. The age and thickness of the bark 

 present no obstacle, nor does the fungus seem to have any prefer- 

 ence for susceptible points, such as crotches and eyes. 



To the casual observer the first visible sign that the disease has 

 fastened itself upon the tree is the wilting of a portion of foliage 

 for no apparent reason. This may occur at any time during the 

 growing season. Upon closer examination there wall be found a 

 ring of dry bark completely encircling the base of the wilted 

 member, and in a short time the spore bearers of the fungus will 

 be scattered thickly over the entire surface of the dry bark. 

 These spore bearers are about the size of a pinhead, and at first 

 are of the color of raw sienna, turning a dark umber with age. 

 The width of this wilted ring on the bark may be anywhere from 

 I inch on a small branch to 3 or 4 feet on a larger limb. 



As far as may be inferred from the many cases under obser- 



