19. From a distance, ink disease and blight are sometimes dif- 
ficult to distinguish, but on clese: inspection the infected trees are 
easy to differentiate. Entire trees may be killed by both diseases, 
but trees killed by the ink disease do not normally produce sprouts 
from the base while those killed by chestnut blight nearly always 
sprout vigorously. On examining the bases of trees affected with 
blight, one will find white- to buff-colored mycelial fans in the bark; 
these are lacking in trees affected with ink disease. Trees that are 
weakened by ink disease, sometimes with limbs killed, turn brown 
and look as though they were infected with the blight, but closer 
examination of the bark wil] reveal which of the two diseases is 
present. 
G. MEANS OF SPREAD OF THE BLIGHT FUNGUS 
20. Detailed studies in the United States indicate that there are 
various ways in which the blight may be spread. These same means 
of spread undoubtedly are operating in Europe. 
21. The blight fungus is well equipped for local spread. In moist 
weather spores of one kind ooze out of infected trees in small 
yellowish-buff tendrils ; these are sticky and can be carried easily 
to other trees by squirrels, birds, insects, knives, and other means. 
Spores of the other kind are shot into the air and are carried by 
wind. Usually both kinds of spores are produced in abundance, but 
a spore must be deposited in a wound or break in the bark of a 
chestnut or susceptible oak before it can cause infection. 
22. Shipment of infected nursery stock is the most important 
means of long-distance spread of the blight. In the United States, 
infected nursery stock shipped from Pennsylvania to Oregon resulted 
in a spot infection over 2000 miles from the original infection. 
Planting of infected nursery plants resulted in numerous advance 
spot infections in the Eastern States, far ahead of the main line of 
advance of the disease. The disease increased in the native chest- 
nut growth around these advance spot infections that resulted from 
infected nursery shipments, and so the time of death of the stand 
in those sections was years ahead of what it -would have been if 
they had been killed by blight that spread naturally. Early stages 
of blight infections cannot always be detected by inspection of 
nursery stock. This also applies to infected scion wood, but the 
danger in the latter case is much less. 
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