July, 1890. , 
135 
ORCH IVR D |rnd^ GRRDEN \ 
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The singular growths, called “cedar apples," 
which result from the action of the fungus 
upon the Red Cedar, are by many consid- 
ered a natural product of that tree. 
The life history of this parasite has been 
carefully investigated by our mycologists 
and the various stages of its development 
made known. This development is most 
interesting and as the fungus often occa- 
sion.^ consider a bl^ injury by its attacks up- 
on the Apple, it will be especially so to the 
fruit grower. 
The attacks of the fungus on the Apple 
tree are first indicated during the latter part 
of May or early in June, by more or less 
numerous bright orange yellow spots which 
appear on the leaves. At these points of 
discoloration the leaf-tissues are somewhat 
thickened. If. after a few days, we exam- 
ine the spots closely we will discover very 
"minute nearly black points on the upper 
surface. These are the spermogonia which 
if viewed under the microscope are seen to 
be hollow bodies that are lined with slender 
filaments bearing at their ends very minute 
spores that have been termed spermntra. 
The exact office or function of these sper- 
matia in this case is not known. If, some- 
what later in the season, we again examine 
the spots we will see, this time upon the un- 
der side, a number of little cups, each with 
a lacerated or fringed border. A cluster of 
these little cups is illustrated in figure 280. 
Within them 
will be found a 
fine, brownish, 
powdery subs- 
tance, the spores 
of the Bw.stelia, 
each particle, 
too minute to 
be seen with the 
naked eye, be- 
ing a spore. The 
spores of this 
showing the under side with the sl “e> e " re canto 
cluster-cups. aecidio spores. A 
couple of them are shown, very much mag- 
nified, at a in figure 279; and at h in the 
same figure the manner of tlie’r germina- 
tion is illustrated. This germination is eas- 
ily induced but as soon as the contents of 
the spore is exhausted, all further develop- 
ment ceases, unless the spores happen to he 
resting on the leaves of the Red Cedar, in 
which case the germ-tubes penetrate to the 
tissues within the leaves, where the food 
necessary for their continued growth is 
found. They will not grow on the leaves of 
the apple, where they were produced, but 
germinating on the Red Cedar, they develop 
an abundant mycelial growth in the leaf 
tissues. The action of the mycelium 
upon the cells composing this tissue is to 
cause them to enlarge and multiply quite 
rapidly in an abnormal manner, resulting 
in the production of a hard, rounded, usu 
allv somewhat kidney-shaped body — the 
“Cedar Apple" — varying fr< m a half inch to 
an inch and a half in diameter. These at- 
tain their full size in the early spring 
months and at that season the Cedars are 
often seen bearing quite a crop of these 
peculiar “apples". In this locality we have 
counted several hundred upon a single tree. 
During the warm rains of April and early 
May, the fungus within the “Cedar Apples” 
comes to maturity and pushes forth a num- 
ber of yellow horn-shaped processes which, 
if the weather is wet, swell up and become 
soft and jelly-like. These out growths are 
often an inch or two in length and from 
their number and bright color, the “Cedar 
apple" oecomes a conspicuous object. Fig- 
ure 278 is designed to show a “Cedar Ap- 
ple” with its horn-shaped but jelly-like 
appendages. These last consist of a mass 
of swollen mycelial tubes, which have 
grown out from the body of the “apple” 
and which bear upon their free extremities, 
two-celled spores like those at c in figure 
279. These spores germinate very soon, 
even while still adhering to the jelly-like 
mass supporting them, but in manner quite 
different from that of 
the aecidio spores des- 
cribed above. They 
push forth a slender 
tube (sometimes several 
of them) along which 
are produced a number 
of very minute simple 
spores called sporidia. 
These sporidia are real- 
ly the seeds of the 
Cedar Apple fungus, 
for it is bv them that 
the parasite is propa- 
gated. They will ger- 
minate and grow, how 
ever, only upon the 
leaves (or fruit) of the 
apple tree and their 
product is the Apple 
Rust. The fungus, 
therefore, presents in 
its complete develop- 
ment two very distinct 
stages: — one on the 
in optical Apple, the Bcestelia 
Gennlna- 
pirata or Apple Rust 
the other on the 
development of the new crop of spores on 
the “Cedar Apples.” 
The fruit, when attacked by the Rust, is 
rendered worthless, and the ripening of the 
fruit is occasionally prevented on account 
of the early destruction of foliage by the 
fungus. We have seen trees practically de- 
foliated by the first of August from this 
cause. 
PREVENTION OF THE DISEASE. 
The Rust fungi are among the most diffi- 
cult to combat; their habit of passing cer- 
tain periods of their lives on different host 
plants and of occasionally becoming peren- 
nial in the plants they attack will account 
for this. As to the Apple Rust, it may be 
said that in localities where the Red Cedar 
is a rare tree or of no value it may be possi- 
ble to free the orchards from the disease by 
destroying all the Cedars. To talk of such 
a course in this region or of gathering the 
“Cedar Apples” before they produce their 
crop of spores, would be simply ridiculous. 
pores. 
Spores of the Gymnos- and 
poranglum or Cedar T , , 
Apple, d. Germinating Red Cedar and farnili- 
rriS:- 1 )' k ”°" n as “ Cedar 
natlng Sporidia. Apple’, named by the 
mycologist Gymnospornnyium macropus. 
The spores from the Bcestelia stage, produced 
in midsummer, pass to the Cedar tree which 
they infect, the resul' b< ing the “CecTar Ap- 
ple” wffiose spores mature in April or May 
and in turn pass to the Apple tree causing 
the foliage of the latter to “rust.” The 
young apples are attacked as well as the 
leaves, the fungus in them produces a swell- 
ing so that the fruit is misshapen and upon 
the swollen part both the spermogonia and 
the little spore-filled cups described above, 
are formed. The “Cedar Apples” die as 
soon as their spore formation is completed, 
but in the Apple tree the mycelium of the 
fungus sometime endures from year to year 
in the young shoots and buds. This accounts 
for the frequent appearance of the rust on 
the earliest formed leaves even before the 
Cedar Apple ( Oymnnstporangium macropus). 
Fig. 278. 
We must seek oilier means of prevention 
and the one which (o us seems most practi- 
cal is that of selecting resistant varieties. 
This power of resistance varies in the same 
variety in different localities. If the or- 
chardist finds that certain varieties are be- 
ing injuried by the Rust, let him discard 
these. We once visited an orchard which 
was surrounded on two sides by Red Cedars 
which in the Spring bore many “Cedar Ap- 
ples;" there were several varieties of apples 
in the orchard but the rust had attacked 
only one of these. All the trees of this va- 
riety were affected in both foliage and fruit. 
So badly were these trees infected that we 
doubt if anything short of their complete 
destruction would destroy the fungus. The 
course we would recommend is as follows: 
1. Remove from the vicinity of the or- 
chard all Red Cedars. 
