6 FARMERS’ 
vigorously growing trees are easily 
recognized by their yellowish- 
brown to orange surface color, 
which contrasts sharply with the 
erayish-green color of normal bark 
(fig. 7). The cankered area may be 
sunken below the surrounding 
healthy bark, raised above it, or 
partly sunken and partly raised 
(fig. 8). After the fungus kills 
smooth bark through to the sap- 
wood, a sunken canker is formed 
when the dead bark dries and be- 
comes thinner than the living bark. 
Fruiting bodies of the fungus soon 
appear on the dead bark. Some- 
BULLETIN 
2068 
times the infected bark of vigorous 
trees is not killed outright and new 
bark tissues grow, forming a swol- 
len canker (fig. 8). Fruiting bod- 
ies of the fungus seldom appear on 
swollen cankers. 
On thick-barked limbs and trunks 
a young blight infection causes very 
little change in the outward appear- 
ance of the bark. As the disease 
progresses, abnormal splits or 
cracks often appear in the thick 
bark, exposing some of the buff- 
colored infected inner bark, and 
fruiting bodies develop in bark 
splits or cracks. 
Freure 5, 
Spore horus of the chestnut blight fungus. 
(About 6 times natural size.) 
