ie., to preclude air and/or water; (3) covering the entire scion (bark 
and buds, as well) with the same water-proof material used to seal the 
union; (4) using only vigorous undisturbed rootstock, preferably 3- to 
4-year-old trees; and lastly, (5) placing the graft in the upper one-third 
portion of the tree crown, regardless of the size or age of the rootstock. 
About 90 percent of all the successful grafts made have died. This 
does not mean that the screening for blight-resistance is a failure. If 
only one or two accessions prove to have sufficient resistance to with- 
stand the blight fungus, our efforts will be justified. 
Some of the American chestnut grafts succumb to the blight during 
the first growing season; others succumb during the second, third, or 
even fourth growing season. But the point is that we still have a few 
of the original grafts—made in 1954—that are still blight-free. These 
too, may eventually succumb to the blight; but even if they do, we 
expect to continue the search for still other heretofore unreported old 
surviving chestnut trees, and to keep the performance of the rest under 
constant observation. 
Because the number of surviving grafts is so small, we feel that no 
valid conclusions can be drawn that sufficient resistance is present to 
warrant their wholesale propagation. Furthermore, when these grafts 
are much older, we shall test them by artificially inoculating them with 
the chestnut-blight fungus. The old surviving native chestnut trees, 
from which the most promising scionwood accessions were obtained, 
will also be inoculated. 
There are still many unanswered questions about the screening 
studies under way, and the occurrence of these large old surviving 
chestnut trees in the area swept by the blight: Why, for example, are 
the largest and oldest American chestnut trees reported from five states 
—Maryland, New York, Pennsylvania, northern Virginia, and West 
Virginia? Past experience with other plants would suggest that a 
resistant sport would be expected to appear anywhere, anytime—but 
particularly in areas of greatest plant population. In the southern 
Appalachian region the American chestnut represented one tree in 
every four as a component in the forest. Yet we have not received any 
scionwood from large recorded survivors in this general area. There 
are, of course, still many single trees or groups of old American chest- 
nut trees scattered throughout the Midwestern and Pacific Coast States 
(planted outside their natural botanical range), but most of these have 
never been exposed to blight infection. 
In summary, nearly 150 American chestnut trees over 8 inches in 
diameter have been included in our screening program. Most of these 
have apparently been escapes, since they succumbed to the blight when 
grafted onto scionwood in other locations. Yet some of the grafts are 
still living. This gives us hope that there may be genetically resistant 
trees that survived the original blight. This progress is heartening. It 
has been made possible through the cooperative efforts of many people 
who are willing to find these surviving trees and to assist in screening 
them for blight resistance. 
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