304 
study areas. Mycelial mats, fig. 15, ap- 
peared on only 17 of the bark pieces, table 
11. The first such growth known to ap- 
pear was found on March 24; the last 
in the early part of April. No visible my- 
celium of the oak wilt fungus tormed on 
the wood pieces at any time. This ab- 
sence of growth on the wood is not ex- 
plained, as it was shown earlier by Curl 
et al. (1953) in Illinois that mats of En- 
doconidiophora fagacearum developed on 
both bark and wood on the forest floor. 
All pieces of bark that produced a visible 
growth of fungus had been placed on the 
ground 2 weeks before the fungus ap- 
peared. Most pieces on which the fungus 
was not visible after 2 weeks were very 
dry or were overrun by other fungi. Wood 
and bark placed on the ground after April 
Ittinois NATURAL History Survey BULLETIN 
Vol. 26, Art. 3 
dried too rapidly to allow the fungus to 
develop, at least in visible amounts. 
Decline of Mats 
The rate of progress of mycelial mats 
from the immature stage to a deterior- 
ated condition varied considerably accord- 
ing to the time of year when the mats ap- 
peared, table 12. Most immature mats 
found during November, December, and 
January required 70 to 84 days to reach 
a stage of deterioration. Mats that were 
found in the immature condition during 
February, March, and April became dete- 
riorated in about 42 days, and mats that 
formed in May, June, and July declined 
very rapidly, sometimes requiring less 
than 14 days for complete deterioration. 
Table 11—The development of mycelial mats of Endoconidiophora fagacearum on bark 
and wood pieces that were taken from diseased oaks and placed on the forest, floor. 
MontH 
(1952-1953) te ee 
Pieces 
Noveniters ne ctt ele. clots 22 
eceniiere et fo cee wee eee 20 
PMNUARG Ss hee oes ae ease ae ei) 
Hebrugty: 2 hese eee eae 20 
rate eee eS ee a a 40 
PRE eee cess oo ns) ome oi 27 
ut Fe a Re eR ae 21 
Bete act ete Se eee 21 
fA) | SR Fl Cy Re A Ei 213 
BarK 
Woop 
Number With | Number of | Number With 
Mats Pieces Mats 
0 20 0 
0 14 0 
0 14 0 
0 9 0 
4 22 0 
13 13 0 
0 14 0 
0 11 0 
17 128 0 
Table 12.—The rates of development and decline of mycelial mats of Endoconidiophora 
fagacearum appearing on wilt-killed oaks; as indicated by the condition classes of the mats at 
14-day intervals, the rate of development and decline of each mat was influenced by the month 
in which it first appeared. 
Conpition Criass* or Mats on DEsIGNATED NuMBER OF Days AFTER FIRST 
APPEARANCE 
Monto Mat 
APPEARED 
0) 14 28 42 56 70 84 
Days Days Days Days Days Days Days 
November........ I II Ill IV IV IV V 
December........ I II Ill IV IV V 
Jannary.ce . foe: I II Ill IV EY. Vv 
February......... I Ill IV V 
March. (3... 0522-602 I Il Ill V 
April I II IV Vv 
AG OP rc. Sas I I] V 
GUS ale iad aon Coes I V 
WS oh Bbc oO eo ese ] V 
*Condition class I, immature; II, mature; III, 
aging; IV, declining: V, deteriorating. 
