292 
ILt1Nnois NATURAL History SuRVEY BULLETIN 
Vol. 26, Art. 3 
Table 5.—Germination of cells from pads of mycelial mats of Endoconidiophora fagacearum 
at various centigrade temperatures on 2 per cent water agar. 
NuMBER era Bw) 
or Hours 
8° 15: 
|) BO ee ee 0 6 
ce att: Thee: 0 28 
SBF eee hee. 7 BT], 
ee rT Wee es 17 60 
Ge ak ae She 31 60 
Per Cent GERMINATION AT DESIGNATED TEMPERATURE 
22" 28° 34° 
28 30 0 
63 36 0 
65 41 0 
70 43 0 
71 50 0 
mum temperature for germination than 
have conidia and ascospores. Also, the 
ability of germinated pad cells to sporu- 
late abundantly on water agar seems to 
equal that of germinated conidia, fig. 8E, 
or ascospores. 
Production of Perithecia 
In conjunction with the study of peri- 
thecium formation under natural environ- 
mental conditions, a short experiment was 
conducted in vitro to determine what tem- 
peratures most favored the formation of 
perithecia. A wheat bran agar medium, 
consisting of 30 gm. of wheat bran and 
20 gm. of agar in 1 1. of water, was 
used. Drops of a spore suspension from 
each of two compatible strains of Endo- 
conidiophora fagacearum were placed ap- 
proximately one-half inch apart on the 
surface of the medium near one edge of 
each plate. The plate was then slanted, 
forcing the drops to flow parallel with 
each other to the opposite side of the plate 
and, thus, distribute spores uniformly on 
the medium. All plates were incubated 
at 25 degrees for 7 days, and then placed 
in groups of six, each group for 16 more 
days at one of these temperatures: 7, 12, 
16, 25, and 31 degrees. Perithecia were 
counted if the necks could be seen above 
the substrate with a binocular microscope. 
An average of 51 perithecia per plate 
developed at 16 degrees, 47 at 25 degrees, 
and 11 at 12 degrees, table 6. At the end 
of the 16-day incubation period, no peri- 
thecia had appeared in plates subjected to 
either 7 or 31 degrees. Similar results 
were obtained when the experiment was 
repeated. 
Longevity of Conidia 
The following experiment was con- 
ducted to determine the extremes of tem- 
perature and desiccation at which conidia 
of Endoconidiophora fagacearum may sur- 
vive. Wooden tree labels, each 3.5 inches 
in length, were boiled in water for 1 hour. 
They were then placed on end in 250-ml. 
Erlenmeyer flasks, each containing 75 ml. 
of a wheat bran broth, and steam steri- 
lized. The broth was seeded with drops 
of a conidial suspension and the flasks 
were incubated at 25 degrees for 2 weeks. 
Table 6—Production of perithecia by Endoconidiophora fagacearum at various centi- 
grade temperatures on wheat bran agar. 
Rep.icate No. 
i hes Ips 
| A carla eee gay eames 0 8 
De PaO a eee ee oes 0 9 
Pir tis eahr asi e 0 5 
7 Rok ae 0 22 
Bios enetaid Bead Rar z ea 0 7 
pats ao osteo 0 14 
OGRE. winiceae vale 0 11 
* No count possible; agar overrun by Graphium sp. 
NuMBER OF PERITHECIA AT DESIGNATED TEMPERATURE 
16° 25° Ki be 
38 91 0 
60 16 0 
32 51 0 
73 * 0 
37 66 0 
67 10 0 
51 47 0 
1 
] 
| 
' 
