CHESTNUT TREE BLIGHT. 21 
branches beyond the point of attack, and the remainder of the tree 
may survive for several years (fig. 3). 
Some of the symptoms are quite prominent. Limbs with smooth 
bark attacked by the fungus soon show dead, somewhat discolored, 
sunken areas (occasionally with a raised margin), which continue to 
enlarge and soon become covered more or less thickly with yellow, 
orange, or reddish-brown spots about the size of a pinhead. These 
spots are the pustules of the fruiting fungus. In damp weather or 
in damp situations, masses of summer spores are extruded in the 
form of long, irregularly twisted strings or “horns,” which are at first 
bright yellow to greenish yellow or even buff, becoming darker with age 
(Pl. XVI, fig. 3). If the lesion is on the trunk or a large limb with 
very thick bark, there is no obvious change in the appearance of the 
bark itself, but the pustules show in the cracks and the bark often 
sounds hollow when tapped. After smooth-barked limbs or trunks 
are girdled the fungus continues to grow extensively through the 
bark, sometimes covering the entire surface with reddish-brown 
Fic. 3.—Large chestnut tree partly killed by the bark disease. Note the sprouts with leaves near the top, 
the dwarfed leaves on the lower right-hand limb, and the healthy lower branches with leaves. 
pustules (fig. 4). These pustules produce mostly winter spores 
(ascospores), although occasionally the long strings of summer spores 
(Pl. XVII, fig. 3) are also produced, even on bark that has been 
dead at least a year. 
After a branch or trunk is girdled, the leaves change color and 
sooner or later wither. Such branches have a very characteristic 
appearance and can hardly be mistaken for anything else, except in 
certain localities where the work of twig-girdling insects may pro- 
duce a similar appearance in the spring. In case the girdling by 
the fungus is completed late in the season, the leaves of the ee 
ing spring assume a yellowish or pale appearance and do not develop 
to their full size (fig. 3). If the girdling 1s completed between spring 
and midsummer the leaves may attain their full size and then turn 
a somewhat characteristic reddish-brown color, which can easily be 
detected at a long distance. Later this leaf coloration changes to 
a more brownish tinge and the leaves are commonly persistent for a 
considerable time. The chestnut fruits (burs) on a spring-girdled 
