THE TEXAS ROOT ROT FUNGUS AND ITS CONIDIAL 
STAGE! 
B. M. DUGGAR 
Physiologist to the Missouri Botanical Garden, in Charge of Graduate Laboratory 
Professor of Plant Physiology in the Henry Shaw School of Botany of 
Washington University 
More than twenty-five years ago Pammel ('88, '89) spent 
two summers in Texas investigating an important cotton dis- 
ease popularly known as the ‘‘cotton blight’’ or “cotton dy- 
ing,” and as а result of his observations two reports were 
published upon the cotton root rot,—the latter more appro- 
priate name being applied by him to the disease in question. 
He determined the causal organism to be a sterile fungus 
found in some abundance on every dead or dying root, and it 
was tentatively identified as Ozonium auricomum Lk. After 
a study of Link’s type, Shear (707) described the organism as 
a new species, O. omnivorum. 
Since the work of Pammel the disease has doubtless been 
the object of numerous field observations, more or less exten- 
sive, but so far as is personally known to me, and so far 
as reports are available, the only records are those of Dug- 
gar (709, observations made 701, ’02), Shear (707, observa- 
tions beginning in '02), Shear and Miles (207, 707%), Heald 
(209, 711), and Heald and Wolf (711, 19). The disease is un- 
doubtedly one of the most destructive of the cotton fungi, and 
the average losses sustained in the state of Texas have been 
variously estimated by Orton ('06) and others to be two to 
three million dollars. In addition, considerable damage is 
sustained by such erops as alfalfa, beans, sweet potatoes, and 
certain orchard fruits. 
It would appear that the organism is very largely confined 
їо Texas. In that state it seems to have been commonly ob- 
"The writer was engaged in a study of cotton diseases, Ди зе тъй Ше Texas 
root rot, in Ше Bur reau ы Plant Industry during the seasons of 1901-02. In the 
fall of 1902 the work was transferred to Dr. C. L. Shear. Now that the Missouri 
Botanical Garden is giving ple cie attention to a botanieal survey a certain sec- 
tion of the Southwest, it has seemed appropriate to resume the studies of this 
fungus so wide-spread and pe espinas, in a large part of that region. 
Ann. Mo. Bor. Garp., Vor. 3, 1916. (11) 
ve dA ы. e 
