ROOT ROT OF THE GRAPEVINE IN MISSOURI CAUSED 
BY CLITOCYBE TABESCENS (SCOP.) BRES . 12 
By Arthur S. Rhoads 
Assistant Plant Pathologist, Agricultural Experiment Station of the ‘University of 
Florida; formerly Pathologist, Missouri State Fruit Experiment Station 
INTRODUCTION 
Shortly after the writer had as¬ 
sumed his duties at the Missouri 
State Fruit Experiment Station in 1922 
his attention was directed to reports 
received from several localities of the 
destruction of grapevines caused by 
root rot. The first opportunity to in¬ 
vestigate this disease was afforded by a 
trip to Knobview, Mo., on May 30, 
1922, where, in the vineyard from 
which the trouble was reported, a 
number of vines that had recently died 
were carefully dug up. All exhibited 
the same symptoms, namely, an abund¬ 
ant growth of characteristic whitish to 
isabelline mycelial sheets or mats oc¬ 
curring between the layers of the innner 
bark and between the bark and the 
wood of the roots and root crown, oc¬ 
casionally accompanied by black rhizo- 
morphic strands. These symptoms in¬ 
dicated that the disease was caused 
by a mushroom root rot, although no 
fruiting bodies could be found to verify 
the supposition. Cultures and further 
field studies were made which afforded 
a basis for the conclusions herein 
reported. 1 2 3 
HISTORICAL REVIEW 
Although grapevines are known to be 
attacked by several different root rot¬ 
ting fungi, especially when the root 
systems have become weakened or in¬ 
jured, comparatively few investigations 
have been made in this country of 
the resulting diseases. 
Root rot of the grapevine has long 
been known in Europe, where it has 
been investigated extensively. In 
France it is called “blanc des racines” 
or, more commonly, “pourridie; ” in 
Germany “ Weinstock-faule; ” and in 
Australia and some other countries 
'‘white-rot. ” According to Verge (56 ) 4 
the cause of pourridie in Europe is at¬ 
tributed to several of the higher fungi, 
among them being Armillaria mellea 
(Fries) Quel., Dematophora necatrix 
Hartig, Vihrissea (Roesleria ) hypogaea 
Ch. Richon and Le Monnier, and some¬ 
times Psathyrella ampelina Foex and 
Viala. In the United States the dis¬ 
ease has sometimes been attributed to 
these fungi and also to Phymatotrichum 
(Ozonium) omnivorum (Shear) Duggar. 
Most American writers, however, have 
generally believed that the disease in 
this country is caused by Armillaria 
mellea and Dematophora necatrix (51, 
p. 172-174 ), although as a rule on as¬ 
sumption rather than from definite 
evidence. 
Root rot of the grapevine was first 
reported in this country in Missouri, 
Scribner (46, p. 137) stating that it 
was discovered in a vineyard at Bush- 
berg, about 25 miles south of St. Louis, 
by the eminent French viticulturist 
Viala, in 1887, while the two were 
making a tour of the principal grape¬ 
growing regions of the United States. 
The same author also states (47, p. 12; 
48, p. 64) that they found the disease 
later in northeastern Texas and again 
in Napa Valley, Calif. He records the 
fact that he has seen a number of vines 
nearly or quite dead from the same 
disease in the vicinity of Knoxville, 
Tenn. 
In 1892 Pierce (38 p., 153-161), dis¬ 
cussing the relation of root-attacking 
fungi to the California vine disease, 
states that Dematophora, although 
found in several places in the United 
States, had not been seen in California; 
that Armillaria mellea has been re¬ 
ported in northern California; and 
that Vihrissea hypogaea was found in 
1 Received for publication May 19, 1924; issued April, 1925. 
2 Commonly known in this country under the names Clitocybe monadelpha (Morg.) Sacc., Armillaria 
mellea exannulata Peck, Clitocybe parasitica Wilcox, and Monadelphus caespitosus (Berk.) Murrill. 
3 The writer gratefully acknowledges helpful advice and suggestions concerning the taxonomic treat¬ 
ment of the fungus under discussion from Dr. E. A. Burt of the Missouri Botanical Garden, Dr. L. O. 
Overholts of the Pennsylvania State College, and C. G. Lloyd of the Lloyd Library and Museum at 
Cincinnati. Grateful acknowledgment is made of the invaluable services rendered by the libraries 
of the Missouri Botanical Garden and the U. S. Department of Agriculture. 
4 Reference is made by number (italic) to “Literature cited,” p. 364. 
Journal of Agricultural Research, 
Washington, D. C. 
( 341 ) 
Vol. XXX, No. 4 
Feb. 15, 1925 
Key No. Fla.-2 
