Feb. 15,1925 Root Rot of Grapevine Caused by Clitocybe Tabescens 359 
its appearance upon extending their 
plantings into ground more recently 
cleared. 
In all cases where the writer has had 
the opportunity to observe Clitocybe 
root rot, both of grapevines and fruit 
trees in Missouri, it has occurred in the 
low and poorly drained parts of vine¬ 
yards and orchards where water is liable 
to stand in the soil, although it may 
also occur in soils underlaid with an im¬ 
pervious subsoil or hardpan, where 
natural drainage is poor. In Florida, 
however, Clitocybe root rot has been 
observed in sandy soils that appeared 
to be well drained. The relation of 
Clitocybe root rot to inadequate drain¬ 
age was illustrated in very striking 
fashion in a vineyard about 18 years 
old at Neosho. This was planted in 
Moore’s Early grapes on one side and 
Concord on the other. The land was 
practically level. Immediately adjoin¬ 
ing one end of the vineyard was a sor¬ 
ghum field in which, close to the end of 
the vineyard, lay a large, slightly de¬ 
pressed area where water stood for long 
periods during the early summer. 
Even the sorghum in this vicinity had 
made but poor growth and appeared 
stunted and pallid. The grapevines at 
this end of the vineyard were weak and 
unthrifty. Large numbers had died 
out and been removed (pi. 7, upper 
figure), and still others were dying or 
were practically dead. Several of the 
dying vines were dug up and found to 
have the mycelium characteristic of 
Clitocybe root rot. Clusters of the 
mushrooms had even developed from 
the root crowns in some cases. In 
addition, it was determined by the 
cutting method previously referred to 
that many of the living vines which 
appeared to be at least moderately 
healthy were infected by the fungus. 
At the other end of the vineyard, which 
was 520 feet in length and contained 
but 52 vines, there was a full stand 
growing vigorously (pi. 7, lower figure). 
The losses occasioned to vineyards 
by Clitocybe root rot vary greatly. In 
mild cases perhaps just a few vines will 
die from year to year, but in severer 
cases they may die quite rapidly until 
within a few years parts of the vineyard 
may be heavily depleted, as in the case 
just cited. 
CONTROL OF CLITOCYBE ROOT ROT 
OF GRAPEVINES 
A little attention directed to preven¬ 
tive measures will obviate the necessity 
of applying remedial measures in com¬ 
bating root rot which at best are but 
palliatives. In selecting a site for vine¬ 
yard planting, newly cleared land, espe¬ 
cially in a region of oak forests, should 
be avoided, since the fungus may live 
in the soil as a saprophyte on deadwood, 
such as stumps and roots. The charac¬ 
ter of the disease suggests the need for 
thorough preparation of cleared lands, 
including the removal of all roots, and 
cultivation for at least three years in 
other crops before setting out to grape¬ 
vines or fruit trees. In any case, land 
which promises poor natural drainage 
should be avoided unless artificial 
drainage can be assured at a reasonable 
cost. Care should also be taken to 
prevent barking or otherwise injuring 
the roots of vines when cultivating the 
vineyard, since such injuries favor in¬ 
fection by root-rotting fungi. Control 
of the grapevine root borer is also 
essential for the same reason. 
After Clitocybe root rot appears in a 
vineyard the vines that have been 
seriously attacked can not be saved; 
however, measures can be taken to 
check the spread of the disease and to 
save those recently attacked. Inas¬ 
much as an excess of moisture in the 
soil, either as a result of a natural de¬ 
pression or being underlaid by an im¬ 
pervious substratum, is one of the chief 
conditions favoring the development of 
Clitocybe root rot, adequate drainage 
is, and will always be, the most val¬ 
uable preventive and corrective meas¬ 
ure. Unless this precaution is taken 
all others are useless, for vineyards 
that have become infected with this 
root-rot fungus are, unless drained, 
always subject to attack by it. The 
low or otherwise poorly drained places 
in the vineyard where water is liable to 
stand in the soil should receive most 
careful attention in this respect, for it 
is at these points that root rot is most 
likely to occur. As soon as the root 
rot is discovered in a vineyard all vines 
that have been killed by it and all vines 
badly diseased, that is, those whose 
scanty growth shows that their root 
system is seriously attacked, should be 
removed. These should be excavated 
carefully, care being taken to remove 
all the roots, which should be burned. 
Then, if the hole is left exposed to the 
air and sun for a few weeks or disinfec¬ 
tion of the soil is accomplished by the 
use of chemicals, and the drainage of 
the soil has been assured, it should be 
safe to replant. 
In European practice a number of 
chemicals have been applied to the 
soil to destroy the mycelium and spores 
of Dematophora necatrix and other root- 
rot fungi in the soil or to destroy the 
fungus on recently infected vines with- 
