October, 1890. 
183 
ORCHARD f j AND C© ARDEN \ 
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Conducted by Prof. F. Lamson-Scribner, 
Director and Botanist, Experiment Station, 
Knoxville, Tennessee. 
Leaf Spot-Disease of the Plum and 
Cherry. 
( Septoria Cerasina.) 
The leaf-spot disease of the plum and 
cherrj has occasionally been mentioned in 
our horticultural journals as the “shot-hole” 
disease or “shot-hole” fungus, and one 
writer describes it under the name of plum- 
leaf fungus. The fungus which causes 
this disease is very generally distributed 
throughout the States east of the Mississippi. 
It attacks the foliage, and although not 
regarded as a serious pest, it often inflicts 
considerable injury both to the cherry and 
plum by interfering with the proper 
functions of the leaves or by causing these 
to drop prematurely, sometimes as early as 
the first of August. The leaves attacked 
show, at first, scattered here and there over 
the surface, dark purple spots visible on 
both sides, varying from 1-24 to 1-8 of an 
inch in diameter. After a brief period it 
will be noticed that the tissue covered by 
some of these spots has become dead and 
brown in color, Such spots usually have 
their margins clearly defined and are most 
often circular in outline. Sometimes this 
dead tissue drops out from the leaf leaving 
a clear cut, round hole, giving the leaf the 
appearance of having been perforated by 
shot holes, hence the name sometimes given 
to the disease, mentioned above. 
If we examine one of 
the brown spots under a 
lens, we will usually de- 
tect upon the under sur- 
face one to several very 
minute black points_ 
These points are the 
fruits of the fungus-little 
capsules within which 
the spores of the fungus 
are produced in great 
abundance. They, the 
spores, are very slender, 
many times longer than 
broad, and quite transpa- 
rent. The) are usually 
divided by one or more 
cross-walls into two or 
more cells. These spores 
fir. 327 . Leaf-spot serve to propagate the 
disease of tlie cherry, fungus ; each cell in 
A spotted and disco- , . 
lored leaf. every spore being capable 
of producing a new growth of the parasite. 
It is thought that the fungus continues its 
life and completes its development upon the 
same leaves which it first attacks, after 
they are fallen to the ground. The spores 
produced on the old leaves in the spring 
serve to propagate the fungus during the 
new growth of the parts which it infests. 
All infested leaves are more or less dis- 
colored with the purple or brown spots 
mentioned above, or they may turn before 
falling to a clear yellow color. In figure 
327 is shown a leaf of the cherry attacked 
by this fungus, exhibiting a spotted appear- 
ance, the shaded left hand side representing 
a part which has become discolored through 
the action of the parasite upon the leaf 
tissue. Figure 323 represents a highly 
magnified section through the leaf including 
one of the spore capsules ; and at a, above, 
are shown some of the spores still more 
highly magnified. 
We do not know that any direct attempts 
have been made to prevent the disease here 
Fie. 333. Magnified section of cherry leaf, showing 
fungus causing Leaf spot disease; a, four spores more 
highly magnified. 
described. The parasite is one which buries 
itself in the leaf-tissues, and consequently 
whatever treatment is given it must be 
preventive. If the trees are sprayed with 
the sulphate of copper compounds for the 
purpose of preventing plum rot on the 
monilia of fruit, it will be well to observe 
what effect these applications have upon 
the development of the Leaf-spot fungus. 
Fungus Diseases of Crape Vines. 
In our vicinity the present season has 
been a trying one for grapes. At the start 
the weather was such that the grapes failed 
to set well, either through the direct action 
of our late frosts or by some cause which 
seriously affected the proper fertilizing of 
the flowers. And 
as the season ad- 
vanced, nearly 
all the fu ngi, 
known to us, 
which seriously 
affect grape vines 
or their fruit, 
developed to an 
injurious extent ; 
black rot, downy 
mildew, powdery 
mildew, grape- 
leaf blight, an- 
Fig. 325. Le;if of grape, show- thracnose, and 
ing effect of Grape-leaf Blight. bitter rot have 
all taken part in destroying or diminishing 
the crop. 
We take this occasion to illustrate, as 
well as possible by black and white figures, 
the appearance of the leaves of the vine 
attacked by black-rot, by grape-leaf blight, 
Fig. 326. Showing effect of Black-rot fungus on the 
grape leaf. 
and by anthracnose, in order to assist 
grape growers in distinguishing these 
diseases. We have in previous papers called 
attention to the fact that the black-rot 
fungus first appears upon the foliage of the 
vine, even before the flowers have opened, 
and the careful vineyai'dist will watch for 
the appeaxance of the fungus upon the 
leaves and gather and destroy all those 
which are spotted, and, if he has not 
already sprayed his vines with the Bordeaux 
mixture, will proceed to do so at once and 
not wait for the appearonce of the disease 
upon the fruit. It is now claimed by some 
that this early spraying, while the new 
shoots are from 4 to 10 inches long, is the 
one which will prevent the subsequent de- 
velopment of the rot, little value being 
attached to the later 
sprayings. Of course 
this early spraying 
should be preceded 
by a thorough wash- 
ing of the vines 
while dormant, say 
some time in March 
or April, according 
to the latitude, and 
a cai’eful cleaning 
up of the fallen 
berries and trim- 
mings which maybe 
scattered through 
the vineyard. 
In a paper read by 
Fig, 322. Leaf and branch 
of grape, showing effect 
of Anthracnose on these 
parts. 
Mr. B. F. Galloway before the Society for 
the Promotion of Agricultural Science, at 
Indianapolis, he gave an account of some 
experiments xnade by him the past summer 
'JQqQv in treating black-rot. 
The results obtained 
are px-esented below. 
Four preparations were 
lmm/IMr d: o B T T deaux mix ‘ 
i tux'e ; 2. The ammoma- 
cal carbonate of copper 
solution ; 3. Carbonate 
Fig. 324. Magnified view nf oonner in snsnension ■ 
of Black-rot fungus as OI co PP el 111 suspension, 
seen in grape leaf ; a, 4. Bordeaux mixture 
spores more highly mag- , , 
nifled. and ammomacal car- 
bonate of copper solution, three applications 
of the former followed five of the latter. The 
vineyard experimented upon was located 
near Washixxgton, D. C.,aad consisted of 
