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872 REPORT OF TIE ‘COMMISSIONER OF AGRICULTURE. 
12.—THE ROSE PHRAGMIDIUM. ae 
Phragmidium speciosum, Fries. 
(a) GENERAL OBSERVATIONS. 
The Rose Phragmidiwm belongs to the Uredinie or rust-produc- | 
ing fungi, and like the preceeding, to which it is closely related, it is 
a parasite of the rose, confining its attacks, however, to the stems, 
rarely, if ever, infesting the leaves, although it issometimes found 
upon the leaf stalks. It was first described by Schweinitz, an Amer- 
ican botanist, in 1822, under the name Seiridiwm marginatum. Later 
it was placed in the genus Phragmidium by Fries, who named it 
Phragmidium speciosum. 
It is quite generally distributed throughout this country, and com- 
plaints have been received by this Section of the injury it has oc- 
casioned, one correspondent stating that his plants had been infested 
for four or five years, the stems attacked being invariably killed. 
(6) BOTANICAL CHARACTERS. 
Doubtless this species produces the same spore forms as does Phrag- 
midium subcorticium, but the samples forwarded to us for investi- 
gation exhibit only the last stage or mature form. Jn this condition 
the fungus appears on the stems as illustrated in Plate IX, Fig. 6, 
thickly covering them with black, irregular masses, suggesting at 
first sight the appearance of certain species of bark-lice. A closer 
inspection of the cushion-like masses reveals their true nature, and 
a microscopical examination shows that they are really composed of 
a dense growth of fungus spores supported on long slender stakks. 
Several of these spores are represented in Fig? 7. They are brown in 
color, five to seven celled, with a somewhat abruptly-pointed color- 
less apex, and are particularly attractive objects under the micro- 
scope. In size they are about 304 in diameter by from 70 to 100m 
inlength. Thesupporting stalk is many times the length of thespore, 
slightly tinted in its upper part, but colorless below, and nearly uni- 
form in diameter throughout. 
The body of the fungus (stroma), from which arise the spores, does 
not penetrate into the woody tissue of the stem, but its growth seems 
to be confined to the inner bark and cambium layer, the lifeof which | 
it destroys. In severe cases the stems are often completely girded 
by the parasite, so that the fatal results arising from its attacks are 
not difficult to understand. 
(¢c) TREATMENT. 
The fungus re-appears each year on the same stems, if they survive, 
indicating that it is perennial in habit, a fact making it all the more 
difficult to combat, for there seemsto be no remedy that will destroy 
the parasite which will not be equally destructive tothe host. 
Heroic treatment with the knife, cutting away all the diseased 
stems and burying them, is all that we can now recommend. _A more 
complete knowledge of the development and life history of the para- 
site may enable us to successfully combat without resorting to such 
severe measures, 
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