Nov. 1, 1925 
Ophiobolus graminis and Take-Ad of Wheat 
803 
A modified Crone's nutrient agar, made according to the following 
formula, was used as the medium in which to grow wheat plants under 
aseptic conditions: 
Potassium nitrate (KNO 3 )_gm__ 1. 0 
Magnesium sulphate (MgS0 4 )_gm__ 0. 25 
Calcium sulphate (CaS0 4 )_gm__ . 25 
Calcium phosphate (Ca 3 (P0 4 ) 2 )_gm__ . 25 
Iron sulphate (FeS0 4 )_ J_gm__ . 25 
Distilled water to make_c. c__ 1, 000. 00 
Agar-gms__ 10. 00 
SEEDS 
Three varieties of wheat were employed in these experiments, 
namely, Goldcoin (Junior No. 6), California Club, and Marquis. 
The first named was used in the greater part of the work. The 
kernels were, in all cases, sterilized 10 minutes in 1-1000 HgCl 2 , 
washed thoroughly in running water, dried at room temperature, 
and planted 1 j! inches deep at the rate of 1 gram per linear foot. 
SOIL 
The soil used in all of the experiments was a silt loam, obtained at 
the base of a hill covered with trees and shrubs, and was, therefore, 
reasonably free from general field-crop soil-infesting organisms. It 
was black, very rich in organic matter, and had a hydrogen-ion 
concentration of about 6.6 P H after sterilization for 2 hours at 15 
pounds pressure. 
TAXONOMY OP THE FUNGUS 
The taxonomy of the take-all fungus is discussed by McKinney 
(. 10 ) 8 and is not taken up in detail here. The parasite was described 
as Ophiobolus graminis by Saccardo (14, P- 349) and this name has 
been generally accepted. Recently Fitzpatrick, Thomas, and Kirby 
(S) concluded that this name is invalid. However, as pointed out by 
McKinney {10), there seems to be justification for continuing to use 
Saccardo's name and therefore the writer is following this older and 
generally accepted usage. 
MORPHOLOGY OF THE FUNGUS 
Throughout the course of these studies numerous mature peri- 
thecia were produced by the New York strain of the fungus when 
grown in pure culture. Perithecia were also produced by this 
strain on wheat plants grown under controlled experimental condi¬ 
tions. These fruiting bodies varied greatly in size and shape, but 
the most of them were typical for Ophiobolus graminis. They 
were always black in color, had loose strands of mycelium about them, 
and averaged about 300 microns in diameter; most of them had 
beaks, which were usually curved. However, the beaks were ex¬ 
tremely variable in length and shape. 
Asci were produced m abundance in pure culture. They came 
out of the perithecium singly, and as they left the ostiole they were 
shot out for a short distance. The ascus wall apparently dissolved, 
usually beginning at one end, when it came in contact with the water, 
3 Reference is made by number (italic) to “Literature cited,” p. 825. 
