June, 1955 
Fig. 12.—Carpophilus larvae feeding on Endoconidiophora fagacearum. 
Curt: Oak Witt INOCULA 299 
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A. Portions of 
laboratory-grown mycelial pad; left, without insects and, right, after exposure for 24 hours to 
larvae. 
for 24 hours to larvae. 
the average monthly precipitation slightly 
lower than in the three northern areas. 
In most cases, trees that wilted in June, 
1952, produced their first mats in 4 to 11 
months, those that wilted in July pro- 
duced their first mats in 5 to 10 months, 
and those that wilted in August produced 
their first mats in 8 to 11 months and con- 
tinued to produce new mats for periods 
of 1 to 4 months, table 10. Most trees 
that wilted in June and July started 
producing mats in the fall or winter fol- 
lowing and they continued to form new 
B. Artificially grown mycelial mats; above, without insects and, below, after exposure 
mats for | to 7 and 2 to 6 months, respec- 
tively, before the wood became too old or 
dry to support growth of the fungus. 
Wilt-killed trees were found to under- 
go a gradual decline between the time of 
incipient wilt and the development of the 
first mats. The first evidence that a tree 
would soon be in the right condition for 
mat formation was the appearance of 
long, dark brown streaks in the sapwood, 
usually in a narrow strip along one side 
of the trunk. In some trees this strip 
started near the base of the trunk and be- 
