Feb. is, 1025 Root Rot of Grapevine Caused by Clitocybe Tabescens 349 
spores typical of Clitocybe tabescens. 
Thus mature fruiting bodies shedding 
spores were developed within approxi¬ 
mately one month from a mycelial 
transfer. 5 
None of the other cultures of the 
series on lengths of wild grape roots 
fruited, some becoming contaminated 
with molds and others drying up. No 
rhizomorph formation was noted on 
any of the lengths of roots, but, when 
the bark was peeled off, all exhibited 
the whitish fan-shaped mycelial sheets 
characteristic of the root rot of grape¬ 
vines found in the field. The source 
of the inoculum for this set of cultures 
was the rotted vine roots collected at 
Knobview in the early part of the 
summer, at which time no fruiting 
bodies were in evidence. 
The type of the root rot, including 
the fan-shaped mycelial sheets and the 
rhizomorphs, of the vines at Neosho 
was identical with that of the Knob- 
view vines first studied, and cultures 
secured from the rotted vine roots bear¬ 
ing sporophores at Neosho agreed in 
every way with those secured from the 
Knobview material. Although the 
writer has had no opportunity to 
attempt the reproduction of this root- 
rot disease of grapevines bv inocula¬ 
tions with pure cultures of the fungus 
isolated from infected vines, he is 
thoroughly convinced that it is caused 
by this rhizomorph-producing fungus. 
In this connection it is of interest to 
note that Knobview, where the writer 
obtained his first cultures of the grape 
root-rot fungus, from which material 
he succeeded in rearing the fruiting 
bodies of Clitocybe tabescens , is but 
about 70 miles by air line from Bush- 
berg, where Scribner (46, p. 137) re¬ 
ported the discovery of grape root rot 
in this country in 1887. The evidence 
at hand strongly indicates that the 
organism isolated by the writer, which 
causes a more or less serious root rot 
of grapevines in many sections of 
southern Missouri, was likewise the 
cause of the root rot reported 38 years 
ago, rather than Armillaria mellea, as is 
generally believed according to Piper 
and Fletcher (39, p. 7) and Hesler and 
Whetzel (20, p. 97). 
On June 12, 1923, a series of cultures 
in Erlenmeyer flasks was begun with a 
view to observing the production of 
rhizomorphs and fruiting bodies where 
a large quantity of the substratum and 
a larger space for growth were pro¬ 
vided. Six cultures were made in 500 
c. c. flasks containing a quantity of 
small pieces of roots of a wild grape¬ 
vine (Vitis aestivalis Michx.). Twelve 
other cultures were made in 150 c. c. 
flasks filled to a depth of three-quarters 
of an inch with agar. Six of these con¬ 
tained maltose agar, the other six 
raisin agar. One of each of these three 
sets of six flasks was inoculated with a 
pure culture of the Florida form caus¬ 
ing root rot of eucalyptus, which was 
kindly furnished by Miss C. Audrey 
Richards, of the Madison branch of the 
Office of Investigations in Forest 
Pathology, Bureau of Plant Industry, 
United States Department of Agri¬ 
culture. The remaining five flasks in 
each of the three sets of six were 
inoculated with pure cultures of the 
grapevine root-rot fungus secured by 
the writer at Knobview, Mo. 
All the cultures made a slow but 
steady growth after the lapse of a few 
days. The different cultures presented 
certain minor variations in the appear¬ 
ance of the superficial mycelium, but 
no greater difference appeared between 
the two root-rot fungi than occurred 
in any one group of the three different 
substrata. The cultures all exhibited 
the same general appearance in so far 
as the aerial mycelium was concerned. 
The marginal growth, as a rule, was 
rather sparse and downy-appressed. 
At the center of the cultures the my¬ 
celium developed into thickened com¬ 
pact masses which sometimes were 
quite nodular at first. In some in¬ 
stances the downy-appressed marginal 
growth was lacking, the feltlike my¬ 
celial growth being thickened and con¬ 
vex clear up to the margin. The my¬ 
celium was white at first, but soon 
turned to a dirty white, later changing 
to isabelline or light buff, and eventu¬ 
ally becoming light tan in the older 
portions. 
After the lapse of from ten days to 
two weeks it was noted that in all of 
the six cultures on raisin agar the agar 
had become strikingly discolored, be¬ 
coming dark brown in advance of the 
mycelium, whereas such a discolora¬ 
tion did not occur in any of the cul¬ 
tures on maltose agar. When but a 
5 In this connection it is of interest to note that Totten (53) reported cultural studies of this fungus (as- 
Clitocybe cespitosa), but made no mention of the production of fruiting bodies. A report of the writer’s 
successful rearing of the sporophores of this fungus was given in the following: Rhoads, A. S. clitocybe 
parasitica as a cause of root rot of grapevines. Paper presented at 17th Annual Meeting, Bot. 
Soc. Amer. (Mycol. Sect.), Cambridge, Mass., December, 1922. [Not published. Title in program,, 
p. 13.] On the same program there also appeared an abstract of a paper by Miss C. Audrey Richards Ul) 
in which report was made of the rearing of sporophores of the latter fungus isolated from a piece of rotted 
eucalyptus root sent from Florida. Clitocybe monadelpha is but one of the several synonyms of Clitocybe 
tabescens , the discussion of the history and nomenclature of which will be deferred until later. These 
joint reports constitute the first record of the development of sporophores of this fungus in artificial cultures. 
