a 
nee 
50 BULLETIN 1347, U. S. DEPARTMENT OF AGRICULTURE 
rot of wheat in Utah. In 1921 the writer made plating studies of 
a considerable quantity of diseased wheat material from Fremont 
County, Idaho. Helminthosporium, sativum was obtained in most 
cases. The symptoms manifested by these diseased wheat plants 
answered the description given by Raeder (58), and they were indis- 
tinguishable from the symptoms produced by H. sat¢vum. in the cen- 
tral wheat regions. 
During the past five seasons the writer has made many field 
observations in different parts of the winter-wheat regions and has 
made many culture platings from the diseased wheat plants collected 
by him and by others. In many cases Helminthosporium sativum 
has been found associated with other parasites, and it has been diffi- 
cult and often impossible to determine just how much of the crop 
damage could be attributed to A. sativum. This is especially the 
case In certain parts of Kansas where Ophiobolus graminis, Wojno- 
wicia graminis, H. sativum, and several species of Fusarium occur 
together and in parts of Wisconsin where H. sativum is associated 
with Gibberella saubinetu. Ona basis of the literature and from the 
writer’s observations it appears that ZH. sativum does not cause such 
heavy losses in the winter-wheat belt as it seems to cause in the 
spring-wheat belt. Severe seedling infection or seedling blight of 
winter wheat, amounting to economic importance, has. never been 
noted by the ‘writer. Severe infection of the outer leaf sheaths of 
seedlings frequently occurs, especially in early-sown fall wheat 
(44, 45), but it appears that this infection seldom injures the plant 
asa whole. Root lesions have never been found abundantly on fail- 
wheat plants, and such lesions have never been noted to occur exten- 
sively during the spring and summer growing periods. 
DESCRIPTION OF THE DISEASE 
FIELD APPEARANCE 
The field spotting which several workers (13, 26, 65) report as 
caused by Helminthosporium sativum does not seem ‘to be produced 
in all localities where the parasite occurs. This spotting seems to 
be prevalent in the spring- -wheat region, but we writer has never 
noted in winter wheat a field spotting ; which wa certainly caused by 
H. satiwwum. A spotting in wheat, fields has bead reported to the 
writer several times from the vicinity of Woodward, Okla., and 
while H. sativum has been found on many of the chicsaced plants 
sent to him, other fungi have been found, and these may play a 
part in causing field spots. On the other hand, it seems ‘probable 
that ZH. sativum will produce more severe injury to winter wheat 
when grown in the more southern regions, which have rather long 
and relatively warm tall periods. Consequently, it would not be 
surprising to find this parasite causing a definite field spotting in 
such localities. 
The rosette disease (44) occurring in certain varieties of winter 
wheat in Illinois and Indiana causes a field spotting, and in some 
cases Helminthosporium sativum is associated with this disease; but, 
as pointed out later, carefully conducted experiments have shown 
that wheat rosette is not caused by ZH. sativum (49). 
