Feb. is, 1925 Root Rot of Grapevine Caused by Clitocybe Tabescens 361 
out injuring the vine itself. Bonjour 
W) recommends the use of a 7 per cent 
solution of green vitriol (ferrous sul¬ 
phate). Beniling and Behaix likewise 
recommend green vitriol against rot of 
vine roots where carbon bisulphide and 
sodium fluoride had no action. Dufour 
(12), however, who has conducted ex¬ 
periments to control pourridie of the 
grapevine for a number of years, tested 
comparatively the action of green vitriol 
and blue vitriol on the causal fungus 
(Dematophora necatrix) and found the 
latter much superior. He recommends 
a 3 per cent solution of blue vitriol 
(bluestone or copper sulphate) as a soil 
disinfectant. This is applied by ex¬ 
cavating a small basin around the trunk 
of the vine and pouring into it a gallon 
or so of the solution, the exact quantity 
being determined by the nature of the 
soil and the supposed extent of the root 
system. Before planting new vines, 1 
to 2 quarts of the same solution are 
poured into the holes. Vines adjoining 
those known to be attacked are also 
laid bare in the spring and watered 
freely with the solution; 3 to 5 ounces 
of granulated bluestone per stock may 
likewise be spread over the ground. 
The result is not always completely 
visible the first year, and it is some¬ 
times necessary to repeat the treatment 
for two years in succession, in which 
case the results obtained are claimed 
to be very positive. 
Dufour likewise tried ammonium sul¬ 
phide, hyposulphite of soda and sul¬ 
phite of lime against Dematophora neca¬ 
trix without securing any promising 
results. Potassium sulphocarbonate, 
which Dufour and Mouillefert tried, 
also proved disappointing. Narbonne 
experimented with sulphur and advises 
laying bare the less badly attacked 
stocks as deep as possible and dusting 
the roots abundantly with sulphur, re¬ 
peating the dusting several times be¬ 
fore the stocks are covered again. 
Carbon bisulphide has been tested 
extensively by numerous investigators 
for the control of insects and root rot 
in vineyards. Dufour made applica¬ 
tions at the rate of 200 gm. per square 
meter, after having removed the dis¬ 
eased roots. According to this eminent 
investigator, carbon bisulphide destroys 
the mycelium of the fungus to a large 
extent. Blunno (3), experimenting 
later in Australia, states that carbon 
bisulphide applied at the rate of 1 
ounce per vine, divided into five 
partial injections made within 6 to 8 
inches from the stem, was effective in 
killing the mycelium living externally, 
that is, during the first stage of infec¬ 
tion. Such a dose, however, was not 
sufficient to destroy the old foci of 
infection represented by the roots of 
the once existing trees, and repeated 
and stronger doses endangered the 
vines. According to the same author, 
ferrous sulphate applied each winter 
for three successive years at the rate 
of 8, 16, and 16 ounces, respectively, 
to each vine was sufficient to restore all 
but two vines in which the root rot 
yielded to a further and slightly modi¬ 
fied treatment consisting of daubing 
the infected part of the stem with a 
solution made up of 10 per cent by 
weight of sulphuric acid and 50 per 
cent of ferrous sulphate. The ferrous 
sulphate was used in preference to 
copper sulphate because it was much 
cheaper. It was applied in the usual 
way by digging a hole around the stem 
6 inches deep with a radius of 12 
inches, at the bottom of which the 
chemical was scattered and the soil 
then replaced. This salt was thought 
to act not only as a fungicide but also 
as a vigorous stimulant to growth. 
Szigethi-Gyula (52) states that ex¬ 
periments in a vineyard located in a 
rather moist situation showed that the 
application of lime at the rate of 2 
kg., or 10 liters of milk of lime, to a 
vine was efficient in preventing pour¬ 
ridie. 
Inasmuch as the mycelium of the 
root-rot fungi is often more resistant 
to toxic substances than the host 
plant, considerable experimentation 
will be necessary before there will be 
found for the control of root-rot fungi 
an efficient and satisfactory fungicide 
that can be recommended for general 
use with safety to the vine. It seems 
to the writer that paradichlorobenzene, 
which has proved so successful in the 
control of the peach-tree borer, would 
be well worth a trial for the control of 
root-rot fungi. So far as is known, this 
chemical is not especially injurious to 
grapevines. The above-mentioned fun¬ 
gicides are not recommended for gen¬ 
eral use, but are merely suggested for 
those who may wish to experiment in 
a small way with them. 
The comparatively simple method 
of aeration and exposure to sunlight 
also has shown encouraging results in 
the control of root rot, both on grape¬ 
vines in Europe and on fruit trees in 
this country. In this method the dirt 
is carefully excavated from about the 
root crown and larger roots and these 
are left exposed to the sun during the 
remainder of the summer, either with 
or without the application of a fungi¬ 
cidal wash. The soil is replaced be¬ 
fore the advent of winter. 
