CELE GN SRR SES Nes Wate a sel haat am Ce ihe ee 
5]h UES aes oh aaa aie 8 Ss 3 it 
> ad) . * ‘ : i* hd . 
i} 
SECTION OF VEGETABLE PATHOLOGY. 369 
foliage. After the leaves have startedyapplications of Bordeaux 
mixture or eau celeste, modified by the addition of carbonate of soda, 
will be beneficial in preventing the spread of the disease. This treat- 
ment should be repeated three or four times during the season, so as 
to protect succeeding growths of leaves. 
11.—ROSE RUST. 
e 
Phragmidiwm mucronatum, Winter. 
(Plates X and IX.) 
(a) HISTORICAL. 
The rust of roses is a disease which has been known to botanists 
and horticulturists for nearly acentury. The minute parasitic fun- 
gus causing the malady was first described by Schrank,* a Kuropean 
botanist, under the name of Lycoperdon subcorticitum. Many later 
botanists have described it under various names. + . 
For a long time it was retained in the genus Puccinia, but Link, 
in 1825, placed it in the genus Phragmidiwm, where it still remains, f 
This parasite is common in Europe and is widely distributed in 
this country, attacking both wild and cultivated plants; in severe 
cases the death of the host is the result. It has recently been ob- 
served in California, by Prof. 8. M. Tracy, infesting to an injurious 
degree hybrid perpetual roses; in one instance a Maréchal Niel, 
growing ina greenhouse, was very badly affected. Tea roses rarely 
suffer from its ravages; it is the hardy, hybrid perpetuals that 
suffer most. 
(b) EXTERNAL CHARACTERS (Plate X, Figs. 1 and 2). 
Early in summer the disease first makes its appearance on the 
leaves, leaf petioles, or young stems in the form of variously-shaped 
lemon-yellow spots, which increase in size as the season advances. 
On the leaves the spots are scattered irregularly over both surfaces, 
being lighter in colorabove and below. These spots mark the points 
of development of the fungus, and as this development progresses 
within the tissues the parasite finally breaks through the epidermis 
on the under surface of the leaves, forming little granular pustules. 
The larger pustules appear on the principal vines, along which they 
* may extend for a considerable distance. When the nerves are thus 
attacked the leaves become twisted and misshapen. 
* Hopp’s Bot. Taschb., p. 68. 
+ Ascophora disciflora, Tode, Mcke. Fung., page 16. Aregma mucronatum, 
Fries, Obs. Myc., I, page 225. Phragmidiwm incrassatum var. rosarum, Wallr,, 
Flor. Germ. Crypt., [V, page 188. Phragmidium mucronatum, Lk., Spec. Plant, 
II, page 84. Puccinia mucronata var. rose, Pers., Syn. Fungi, page 280. Pue- 
cima rose, D.C., Flor. Franc., vol.2, page 218. Uredo rose, Pers., Dispos., page 
13. Uredo miniata, Pers., Syn., page 216. Uredo elevata, Schum., Enum. Plant. 
Sacll., II, page 229. Uredo pinguis, D. C., Flor. Franc., II, page 225. 
¢ it appears to us that the name given this fungus by Link, Phragm*dium mu- 
cronatum, is the one which ought to be adopted, it being the earliest name applied 
to this species in the genus Phragmidium. It is certainly straining a point, need- 
lessly multiplying synonyms, and confusing the citations of authors to revive a part 
of an older name after the fungus has already been published under Phragmidium 
merely for the sake of paying tribute (doubtful in some cases at least) to him who 
first describes the fungus or one stage in its development, 
AG 87 24 
