September, 1889. 
177 
ORCHRRD 
AND 
V\^A'\aa/\/\/\aaa7- 
GARDEN 
CONDUCTED B Y PROF. F. LaMSON SCRIBNER, 
Botanist, Experiment Station, Knoxville, Tenn. 
JExperlments in Treating; Blaek-rot. 
The weather during the present season 
has been most favorable for the develop- 
ment of the Black-rot fungus of grapes. In 
June, during the most critical period, tlaere 
were daily showers preceded by a very hot 
sun and succeeded by cool nights with 
heavy dews. Fungi of all kinds flourished 
and grapes were severely attacked by the 
rot. Under these circumstances the reme- 
dies employed for preventing this disease 
were put to the severest test, especially 
when such varieties as the Concord and Ca- 
tawba were the subjects treated. 
We have experimented this season on 
Concords in a vineyard located far up on a 
steep hillside, a most admirable exposure, 
good soil and vigorous vines, but which last 
year lost more than 95 per cent of the crop by 
rot. The vineyard was therefore thorough- 
ly infected with the disease and this was evi- 
dent enough last spring by the many rotten 
berries still upon the ground and the early 
and abundant appearance of the leaf-spot 
disease on the foliage. 
The preparations used were the Bordeaux 
mixture(8 lbs. sulphate of copper and 10 lbs. 
of lime to 25 gallons of water)and the ammo- 
niacal solution of carbonate of copper (5 oz. 
of the carbonate and 1 quart of ammonia to 
22 gallons of water). Previous to using these 
the vines were thoroughly washed, March 
12, with a simple solution of sulphate of iron 
(50 lbs. of the sulphate to 24 gallons of wat- 
er). Five applications of the Bordeaux mix- 
ture and the carbonate of copper solution 
were made, the first on April 23d, when the 
young shrots were from 4 to 12 inches long, 
and the others at nearly regular intervals 
until June 22nd. At the present date (Aug.9) 
there is an abundance of both preparations, 
still adherent, upon the foliage of the vines 
in spite of the frequent and heavy rains 
during the last fifteen days of July. There 
is so much of the Bordeaux mixture still ad- 
hering to the clusters of the now nearly ripe 
fruit that, as this is designed for the table 
and not for wine, it is feared its market val- 
ue may be affected. It was in view of the 
possibility of this result that a sixth appli- 
cation, originally intended, was not made. 
The leaf-spot disease or black-rot on the 
foliage began to appear May 9th, and from 
this date on it was quite general throughout 
the vineyard although there was very de- 
cidedly less on the vines treated with the 
Bordeaux mixture than on those treated 
with the carbonate of copper solution or 
those untreated; there was no apparent dif- 
ference between these last and we began to 
doubt the efficacy of the ammoniacal car- 
bonate of copper preparation. Later de- 
velopments, however, make it evident 
that it is scarcely, if at all, inferior to the 
Bordeaux mixture. On June 8th we found 
in our experimental plat a single berry af- 
fected with the rot. Between this date and 
June 22nd was a period of showery and 
damp weather, like that above described, 
and there was a general and severe attack 
of the rot. The berries on the treated vines 
were much less affected than those on the 
untreated; from ten vines of the former we 
picked, June 22nd, 4 quarts of specked and 
more or less decayed berries while we got 
the same amount, much more badly diseas- 
ed, from three untreated vines. This was a 
fair comparative showing at that time. 
During July a second attack took place 
which somewhat affected the treated grapes 
but by no means to the same extent as it did 
those which had received no applications, 
the latter were nearly all destroyed. At the 
present time we may announce the results 
of our experiments; they are strongly in fa- 
vor of the treatments. The value of the 
Bordeaux mixture in treating Black-rot, af- 
firmed by us last year, has been maintained 
and we feel almost assured that the ammo- 
niacal solution of carbonate of copper is 
equally efficacious, we certainly can detect 
Spraying Vines. Fig 1503. 
no difference in the effects of these two 
compounds as used by us this season. The 
treated vines have lost a third of what might 
be estimated as a full crop while the loss on 
the untreated is practically complete, there 
being scarcely more than four or five per 
cent of the berries left unaffected. 
Considering the very unfavorable charac- 
ter of the weather; the thorough infection 
of the vineyard from the disease of last year; 
and especially the great susceptibility to 
rot of the variety under treatment, we deem 
the measure of our success highly gratify- 
ing. We cannot hope to free a vineyard 
from the disease in one season, nor yet in 
two, but we may hope, and confidently, that 
with each succeeding season of careful 
treatment, success will be more and more 
complete. In seasons of great humidity the 
rot will doubtless occasion some loss how- 
ever diligently we may strive to check it, 
and in view of this, we would recommend 
the possessors of small vineyards who raise 
grapes only for the table, to use paper bags. 
These put on in good season are a certain 
protection against the rot and at the same 
time prevent the depredations of birds and 
insects. The proprietor of the vineyard 
where our experiments were conducted, Mr. 
J. T. Allen, put on many bags while the 
grapes were in full bloom; in these the fruit 
is now perfect and finely colored. 
The winter treatment with sulphate of 
iron we consider highly important and 
another time we would employ a stronger 
solution, making it up to 50 per cent, and, 
perhaps, adding lo this a small quantity of 
sulphuric acid. The application of this to 
the pruned vines will be likely to destroy 
all the germs of disease that may be resting 
upon them. Unless the grapes are grown 
for wine we would discontinue the use of 
the Bordeaux mixture after the second ap- 
plication as its presence on the clusters 
might depreciate their value, and in the suc- 
ceeding treatments we would use the am- 
moniacal solution of carbonate of copper. 
Should this latter compound prove to be as 
entirely efficient as the Bordeaux mixture 
it will be generally adopted for all the treat- 
ments as it is less exjiensive and, being a 
clear fluid, is applied with less difficulty. 
The strength of the preparations as given 
above ought not to be reduced, we would 
prefer to increase the amount of copper in 
each rather than diminish it. 
Black-rot in the North. 
In the February number of Orchard and 
Garden, page 34, we announced that per- 
sonal observation and reports of correspon- 
dents had led us to believe that the fungus 
of Black-rot of grapes did not attain the 
same vigor of development in the northern 
grape growing regions that it does farther 
to the south, and that the vineyardists of 
Western New York and Northern Ohio had 
far less to fear from this parasite than from 
the Downy Mildew which causes Brown rot 
— the prevailing disease and the chief 
source of loss in that section of the country. 
The Black-rot fungus is a plant, and like 
other plants demands for itself a certain 
amount of heat or length of season, as well 
as moisture, to reach its maximum devel- 
opment. While in New Jersey, Maryland, 
Southern Ohio, Tennessee,, etc., it possesses 
the vigor of a true parasite and attacks and 
destroys the most healthy and soundest 
grapes, farther to the north it loses this vig 
or of habit, becoming less virulent in its at- 
tacks (excepting perhaps in some especially 
favorable localities) and appears only on 
berries which have become injured or dis- 
eased through other causes, for example, the 
fungus of the Downy Mildew. We do not 
wish to be understood as saying that Black- 
rot does not exist in the nonhern districts; 
it is and doubtless was piesent there long- 
before vineyards were planted or even be- 
fore the country was settled by white men, 
growing on the fruit or foliage of wild 
vines, (we have seen it on these as far north 
as Canada); but what w T e do affirm, though 
as yet it is true upon rather insufficient 
data, is that this fungus plays the part of a 
saprophyte rather than a true parasite in 
our more northern vineyards and the losses 
occasioned by it are only secondary. 
We have been lead to repeat here our for- 
mer observations through remarks made 
by Colonel A. W. Pearson in his report to 
the Mycologist of the Department of Agri- 
culture published in Stuben Farmer's Advo- 
