44 FUNGOID PESTS OF CULTIVATED PLANTS. 



early spring before the buds expand. The soil around may also be 

 saturated. 



Sacc. Syll. vii. 2622 ; Gard. Chron. July 7, 1877, fig. 5 ; Mass. PL 

 Dis. p. 260 ; Cooke M. F. 34, 107 ; Plowr. Brit. Ured. p. 225. 



ROSE BRAND. 

 Phragmidium subcorticium (Schr.), PI. III. fig. 51. 



This is the advanced stage of the Rose rust, which it accompanies in 

 the autumn, and forms little blackish tufts on the under surface of the 

 leaves, in succession to the gradually disappearing uredo. 



The uredospores having already been described, we have to concern 

 ourselves with the teleutospores, as seen under the microscope. These 

 are very long and cylindrical, terminated at the apex by a colourless 

 point, and the base continued into a long and swollen, almost bulbous, 

 translucent stem, which is longer than the teleutospore itself, and per- 

 sistently adhering to it. The teleutospore (75-100 x 26-30 /j.) is of a clear 

 but dark brown colour, divided transversely by septa into from three to 

 seven cells, each of which is capable of germination, and the surface 

 minutely rough or warted. These teleutospores are usually collected in 

 little tufts. 



When germination takes place any one of the cells is capable of giving 

 off a short germ tube, or promycelium, which becomes divided in the 

 upper portion into several cells, each of which gives off a short process, 

 which carries a small promycelial sporule. These promycelial sporules 

 are charged with the destinies of dissemination, and are the medium 

 through which other leaves are infected. 



The area of distribution of the brand is accepted as the same as that 

 of the uredo, of which the teleutospores are the recognised resting 

 spores. 



Spray with potassium sulphide and burn all fallen infected leaves. 



Sacc. Syll. vii. 2622 ; Mass. PL Dis. p. 260 ; Cooke M. F. 201 ; 

 Plowr. Brit. Ured. p. 225 ; W. G. S., Gard. Chron. July 17, 1886, p. 76, 

 with figs. ; Grevillea, iii. PI. 45, fig. 3. 



ROSE ROT-MOULD. 

 Peronospora sparsa (Berk.), PI. VI. fig. 52. 



This rot-mould was first discovered in 1862 on a quantity of potted 

 Rose plants in a conservatory. Fortunately it has not become an 

 established pest, and we doubt if it may not be almost extinct, although 

 in such cases revival and re-establishment are always possible. 



Irregular, pale brownish, discoloured spots appeared on the upper 

 surface of the leaves : these extended rapidly, and in a short time the 

 leaves withered and shrivelled up, and ultimately the whole plant 

 perished. 



A delicate greyish mould on the spots was scattered over the under 

 surface of the leaves. The threads which arise from the mycelium 

 are scattered, somewhat torulose, and divided in the upper portion as 

 much as eight or nine times in a forked manner, the final branchlets 

 being scarcely hooked, bearing at their tips the elliptical conidia 

 (20-22 x 15-18 /i). 



