856 
Journal of Agricultural Research voi. xxiii. No. h 
The germination of the corn inoculated with conidia of Gibberella 
saubinetii was influenced by soil temperatures between 8° and 20° C. 
At a soil temperature of 8° the embryos of all the kernels were invaded 
and killed before germination. Germination was reduced an average 
of 57 per cent below the controls at 12 0 and 42 per cent at 16 0 . At 20° 
the reduction in germination was strikingly less, only 8 per cent, and at 
24 0 all the kernels germinated in the seven series grown. 
Only a few of the seedlings emerged in the controls and none in the 
inoculated series at 8° C. At 12 0 about 50 per cent of the seedlings in 
the inoculated series reached the surface before blighting, the remain¬ 
ing plants usually blighting when the plumule was from 1 to 3 cm. long. 
Above this temperature practically all the seedlings emerged and wilted 
while in the first-leaf or second-leaf stage (PI. 4). 
All the com plants at 8° C. blighted; all but about 12 per cent blighted 
at 12 0 ; about half of them blighted after wilting at 20°; only a few 
wilted at 24 0 , and these were chiefly in two series of a very suscept- 
I I 1 
VEGETATIVE PEVELQPtlENT 
GIBBERELLA SAUBINETII 
MflETEff COLONIES GT1. 
o 
O OOOO 0 
I 
BuxxmTm&mis 
P&C£Am&£BUGHT 
ComSE&XJAtGS 
/AWMum&&MrmET/t 
£VXX/M77W£<?Ui9LS 
fiEffCEMV&E BL/GHT 
O 03 O 3 O 0 O 
•••( 30 OOO 
I _J _I_I_I_I_ 1 _L 
8 12 16 20 24 28 32 36 
. SOIL TEflREMTURE, DEGREES GEMl GRADE 
Fig. 8 — Graph showing relation of soil temperature to the vegetative development of the parasite and 
the production of the disease. A graphic summary of the vegetative development of Gibberella sau¬ 
binetii in artificial culture and the comparative quantities of seedling-blight of com and wheat at different 
soil temperatures. The black portion of the circle shows the average percentage of blighted seedlings. 
ible strain of Ninety-Day com. Many of the plants showed root lesions 
and some were weakened by the root attack but usually were capable 
of recovering and later making a medium growth, especially if put at 
the higher temperatures. A few plants at 28°, in the two series pre¬ 
viously mentioned, showed small root lesions but none sufficient to 
hinder the development of the plant. The blight was most severe at 8° 
to 16°, where only a few plants survived, and stopped abruptly at 24 0 . 
At this temperature root lesions occurred in a few cases but in most of 
the series did little damage to the plants. 
The average dry weight per plant of roots and tops of the so-called 
disease-free plants in the inoculated series at temperatures from 12 0 to 24 0 
C., was much below that of the control plants; above this temperature the 
weights were approximately the same. 
The parasite was isolated in pure culture from the seedlings, the 
endosperms, and the roots of the blighted and diseased seedlings. After 
remaining in the soil a week or two there was a development of sapro- 
