14 CHESTNUT TREE BLIGHT. 
According to Sudworth, the range of the native chestnut 1s ‘from 
southern Maine to northwestern Vermont (Winooski River), southern 
Ontario, and southern shores of Lake Ontario to southeastern Mich- 
igan; southward to Delaware and southeastern Indiana, and on the 
Allegheny Mountains to central Kentucky and Tennessee, central 
Alabama, and Mississippi.” The range of the chinquapin is ‘‘from 
southern Pennsylvania (Adams, York, Franklin, and Cumberland 
counties) to northern Florida and eastern Texas (Neches River).” 
The bark disease may, therefore, be expected to occur at any pent 
within these limits, as well as in any other localities where the chest- 
nut is grown as an ornamental or orchard tree. 
CAUSE AND SYMPTOMS. 
The disease is caused by the fungus Diaporthe parasitica Murrill 
(also known as Valsonectria parasitica (Mfarll) Rehm). The spores 
of this fungus, brought by some means from a previously diseased 
tree, enter the bark through wounds; her also in other ways. 
The leaves and green twigs are not directly affected. From the 
oint of infection the fungus grows in all directions through the inner 
bark until the growth meets on the opposite side of the trunk or limb, 
which in this way is girdled. The wood is but little affected. Limbs 
with smooth bark attacked by the fungus soon show dead, discolored, 
sunken patches of bark covered more or less thickly with the yellow, 
orange, or reddish-brown pustules of the fruiting fungus. In damp 
weather or in damp situations the spores are extruded in the form of 
long irregular ‘‘horns,” or strings, at first greenish to bright yellow 
in color, becoming darker with age. Plate XVII, figure 3,shows a part 
of a branch of a diseased chestnut tree magnified 34 diameters. In 
this illustration the typical appearance of the pustules in damp 
weather and the projection of the spores of the fungus in the form 
of ‘‘horns,” or threads, are shown. These threads may be especially 
conspicuous near the edges of diseased areas. If the spot is on the 
trunk or a large limb with very thick bark there is no obvious change 
in the ne acne of the bark itself, but the pustules of the fungus 
show in the cracks of the bark and, on account of the destruction of 
the layers beneath, the bark often sounds hollow when tapped. A 
patch usually grows fast enough to girdle the branch or trunk that 
it is on during the first summer. 
The damage may not be immediately apparent, since the water 
supply from the roots continues to pass up through the compara- 
tively uninjured wood to the leaves, but when in the following spring 
the new leaves are put out they are usually stunted and soon wither. 
The ia of such trees is very characteristic. Plate XVII, fig- 
ure 1, shows large chestnut trees killed by the bark disease. In this 
illustration the trees to the left show the characteristic stunted foliage, 
which indicates that they were girdled during the previous year, 
while the tree on the right having no foliage was presumably girdled 
by the fungus at least two summers before the photograph reproduced 
was taken. Plate XVII, figure 2, shows an orchard tree with recently 
dled branches. Nothing else except an actual mechanical injury— 
reaking off of trunk or limb—produces such an effect as is shown in 
these illustrations. The imperfectly developed leaves often persist on 
the dead branches throughout the summer. 
