Fungoid pests of cultivated plants / by M.C. Cooke.

  • Mordecai Cubitt Cooke
Date:
1906
Catalogue details

Licence: In copyright

Credit: Fungoid pests of cultivated plants / by M.C. Cooke. Source: Wellcome Collection.

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    early spring before the buds expand. The soil around may also be saturated. Sacc. Syll. vii. 2G22; Gard. Chron. July 7, 1877, fig. 5; Mass. PL Dis. p. 260; Cooke M. F. 84, 107 ; Ploivr. Brit. Ured. p. 225. Rose Brand. Phragmidivm 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. Th§ 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 y) 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. PI. 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. YI. 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 /.).
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