352 
Journal of Agricultural Research 
Vol. XXV, No. 8 
the leaves were yellowish, straw colored, markedly withered, and har¬ 
bored any number of different fungi. Cladosporium and Alternaria 
spp. were so common on the leaves and heads as to give the plants a 
distinct, mouldy appearance. A careful survey of the field made on this 
trip and on subsequent visits showed Ophiobolus present at the base of 
many plants growing on the elevations. Numerous plants growing in 
the lower parts of the field appeared just as sickly as those on the knolls, 
but in contrast showed no evidence of the presence of Ophiobolus. There 
was but slight dark discoloration at the crown, and no black fungus 
crusts or fruiting bodies were found. The variety of wheat grown was 
Marvelous. It is a soft, winter wheat, not infrequently used in this 
section. The seed had been procured from a local grower who had 
obtained good yields from the same strain in previous years. This 
field had not grown wheat previously for 20 years and had been used as 
a pasture of red top and timothy (largely red top) for the past 12 or 
14 years. 
Mr. Pool had also another field of wheat, about 500 yards south of 
this, which had been grown from the same lot of seed, but this field, in 
contrast to the one just described, showed normal, healthy looking plants; 
it gave one of the best yields in the county. The soil here was of a dif¬ 
ferent type, darker in color, well drained, and it had received an applica¬ 
tion of manure the previous year. It seems proper to conclude that 
as far as these two fields are concerned the seed played no part in the 
introduction and development of the disease. Furthermore, it is evident 
that as far as ecological factors are concerned the only known difference 
was that of soil condition. 
Shortly after Ophiobolus was found on this farm it was discovered by 
the senior writer on another, near Prairie Grove, about 10 miles away. 
Here also the field was undulating and about 11 acres in size, but, unlike 
the first, Ophiobolus was confined entirely to certain spots at the north 
end. This portion represented the highest part of the field, the soil of 
which in color, texture, moisture content, and acidity was comparable 
to the Pool field. Ophiobolus was sharply confined to spots in a 3-acre 
area which had previously been used as a peach orchard. A fence row 
had formerly delimited the southern edge of this area and had been re¬ 
moved shortly before the land had been prepared for wheat the previous 
fall. The whole* 11-acre field had then received the same treatment, and 
the drill rows had been run north and south, extending across the area 
that had previously been in peach trees and continuing down through the 
remainder of the field. The remaining 8 acres had been used for wheat 
in 1920, com in 1919, and clover for 3 years previous to that. As 
compared with the north end of the field, the stand of wheat on this 
portion was thicker, the plants were larger, and the heads better filled. 
The soil was considerably better physically; it appeared well drained, 
there were no crawfish holes, and the subsoil instead of being a stiff clay 5 
of a grayish color was more or less friable, reddish brown, and not water- 
soaked. 
As just stated, Ophiobolus was found only in the 3-acre portion at the 
north end. Here the wheat as a whole was much poorer, and the general 
appearance of the plants closely resembled that on Mr. Pool's farm. 
Here also many stunted and badly diseased plants showed no signs of 
Ophiobolus. One of the worst infested spots in the field was a strip of 
6 The writers wish to express their thanks to Mr. R. H. Austin of the agronomy department. University 
of Arkansas, for taking samples of the soil and subsoil. 
