CHESTNUT BLIGHT 7 
affected by the blight always have cankers that show the typical 
fruiting bodies and cycelial fans as described on page 7. (Fig. 7.) 
THE CAUSAL ORGANISM? 
The vegetative part of the blight fungus, which is made up of 
very numerous flattened threadlike strands, is called the mycelium. 
5." F ‘anker » left is ken where the 
Ilicore 6.—Lhe central part of the canker at the lett is sun e 
fungus has killed the ae through to the wood. The canker at the right 
is slightly swollen with characteristic cracks. 
It grows in the bark, extending much like the roots of plants in soil. 
As the fungus penetrates, it brings about the death of the invaded 
bark. The mycelium within this dead area is buff colored, but where 
it extends into the living bark at the margin of the lesion it is often _ 
1Suear, C. L., Stevens, Nei, E., and TILLER, Bue eae PARASITICA AND 
RELATED SPECIES. U. 8. Dept. Agr. Bul. 380, 82 p., illus. 917. 
2830°—30——_2 
