828 
Journal of Agricultural Research 
Vol. XXXI, No. 9 
and on low ground. He states, however, that in a few fields the 
infection appeared to be very much heavier on the lower and wetter 
land. Rosen and Elliott (15), working in Arkansas, also state that 
the disease seems to be favored by wet soil. 
One of the writers (McKinney) has observed take-all under many 
different field conditions, and while the disease has appeared to be 
more severe in low undrained portions of some fields, this has not 
always been the case. Obviously such apparent irregularities 
emphasized the necessity for studying the influence of temperature 
and moisture under controlled conditions, and, accordingly, a series 
of such experiments was planned and carried out, the results of which 
are presented herewith. 
EXPERIMENTAL METHODS 
All of these studies were conducted under greenhouse conditions 
in the soil-temperature tanks and in controlled-temperature chambers 
of the Wisconsin Agricultural Experiment Station, at Madison. 
The soil-temperature apparatus and the general methods employed 
in these studies were identical with those used in the studies on the 
Helminthosporium disease (12). The temperature chambers have 
been described by Dickson (f) and it is unnecessary to discuss them 
in this paper. 
The soil used in these studies was a fertile loam obtained from a 
wood lot near Madison. Although this was virgin soil, it was in¬ 
fested with several grass parasites which attack wheat, and it was 
necessary to disinfect all of it. Usually the soil was subjected to live 
steam at about 1 pound pressure for four hours. In other cases it was 
heated for one hour at 10 to 15 pounds pressure. Both methods gave 
good results and produced no toxic effect on the plants. One lot of 
this soil contained somewhat more organic matter than the other, 
as indicated by their moisture-holding capacities of 67 per cent and 
53 per cent, respectively. 
The various soil moistures employed in any one experiment were 
obtained by careful weighings and moisture adjustments before 
putting the soil in the temperature-tank soil containers. All soil 
moistures were calculated on the basis of the water-holding capacity 
of the soil and the moisture content of the soil was maintained as 
nearly constant as practicable throughout the experiments. The 
pots were weighed each day and water was added to replace that lost. 
The wheat seed used in all of the experiments was of the Goldcoin 
variety generally known as Junior No. 6. All seed was disinfected in 
a 1:1,000 solution of mercuric chloride for 10 minutes, then thoroughly 
washed in running water before planting. 
The parasites used for inoculation were obtained from Oregon and 
New York. The Oregon strain was isolated by Hurley Fellows from 
wheat collected near Corvallis, Oreg., in 1921, by A. G. Johnson, 
H. P. Barss, and M. B. McKay. Hie New York strain was kindly 
supplied by R. S. Kirby. Both strains originated from single asco- 
spores, and they maintained their pathogenicity throughout the 
work. The virulence of the Oregon strain seemed to become reduced 
toward the end of the studies, and the New York strain was used in 
its place. The loss of virulence of the Oregon strain may have been 
due to the fact that it never sporulated, and consequently all in- 
L1BRARY 
cereal investigation. 
