318 



The Dictionary of Gardening, 



Rosa — continued. 



possibly some of them may be injurious, in their younger 

 stages, to living parts of the Kose-plants. Tlie most 

 generally hurtful of all the true parasitic Fungi is Rose 

 Blight, which is one of the so-called Mildews, and belongs 

 to the group of Erijsipliew {>:ee Mildew and Oidiuml. 

 Its scientific name is Splicerothern pannoi'a, but it differs 

 generically from Eriisij:>}ie in little save that in each of 

 the minute, black perithecia scattered over the mycelium 

 there is only one ascus. In this lie eight oval spores. 

 8. pannosa grows on all young parts of plants in the 

 form of a dense, pale grey, velvety coat, covering large 

 patches of the surface. The parts attacked by it are 

 much altered in appearance, the leaves becoming blistered 

 and twisted, and the flower-stalks and calyces swollen and 

 distorted. An account of the structure of the Fungi in 

 this family will be found under the headings quoted 

 above. S. j^^^'n'otia is found to grow also on the Peach. 

 The application of powdered sulphur, or of weak solu- 

 tion of sulphide of potassium, will destroy the Fungus 

 without injury to the host-plant. 



Another kind of Mildew has been observed on the 

 lower surface of the leaves of Roses in conservatories. 

 Tliis also forms grey patches, but they are less ex- 

 tensive and far less dense than in the former species. 

 Irregular, brownish spots appear on the upper surface 

 of the leaves; they extend over the leaves, which soon 

 wither. These are the work of Peronospora sparsa, 

 and bear scattered conidiophores, or slender, branched 

 stalks, on which oval conidia are produced, on the tips 

 of the branches. No remedy is known for this Fungus ; 

 and all parts that bear it should be cut off and de- 

 stroyed. See Peronospora. 



The Rose Rust ( Uredo or Lecythen Rosw) and the 

 Rose Brand {PliraymiiUiim mucronatum) are believed 

 to be forms of a single species of Fungus, the Uredo 

 being the summer form of spore, and the Phratimidium 

 the autumn form, or teleutospore. Both forms occur 

 scattered in small masses on the lower surface of the 

 leaves ; indeed, they grow on the same patches of my- 

 celium ; but the Brand appears later in the season. The 

 Rust consists of pale yellow, one-celled, round or oval 

 bodies, covered with very fine, prickly warts. The Brand 

 is made up of very different spores, since each is formed 

 of a row of from four to nine cells, which have a brown, 

 warty outer coat. Each spore is borne on a long stalk, 

 thickened below ; and each ends, at the tip. in a long, 

 conical, colourless papilla or outgrowth. This Fungus 

 is seldom dangerous to Roses ; but it renders the leaves 

 unsightly. Unfortunately, no cure is known ; hence, it 

 is advisable to remove and to burn such leaves as show 

 traces of the Fungus, to prevent it from spreading to 

 healthy plants. See Fhragmidium. 



Another Fungus that, at times, renders the leaves of 

 Roses unsightly, is that known as Asteromn Rosce, Lib. 

 {AcHnonema Rnsw, Fr.), which forms dark purplish-brown 

 spots, with the appearance of fibres radiating from the 

 centre of each. In the spots lie scattered, dark pycnidia, 

 containing two-celled spores. This Fungus is probably 

 only an immature condition of some unknown pyreno- 

 mycetous Fungus. To prevent any extension of the 

 slight harm done by it, remove and burn affected leaves. 



The leaves are liable to become covered, on the upper 

 surface, with a sooty deposit, imperfect conditions of 

 species of Capnodiinn. C. Per>:oonii has been recorded 

 from Roses on the Continent ; but probably the species 

 varies. The Fungus grows chiefly in the secretions of 

 the Aphides so common on Roses ; the dark crust ob- 

 structs access of light and air to the leaves. The best 

 remedy is to get rid of the Aphides, and to clean the 

 leaves, and keep them clean by syrmging or sponging. 



Insects. In Kaltenbach's " Pflanzenfeinde," nearly 

 100 species of insects are recorded as more or less 

 hurtful to Roses, i.e., by feeding upon them as larvse or 



Bosa — continued. 

 as perfect insects : and to that number many more 

 could now be added. Hence, only such as are markedly 

 hurtful to these favourite flowers are selected for notice 

 here. 



The roots may, at times, be damaged by larva; of 

 Cockchafers, and other subterranean foes ; but these need 

 not detain us. The larvaj of .iririhm viridis feed below 

 the bark on stems of Roses, usually close to the origin 

 of a branch. The beetles are from -^-in. to ^in. long, 

 rather narrow, and brassy-green or blue ; they are not 

 uncommon in the South of England. 



The twigs and young leaves are much injured by 

 Aphides or Green Flies, of which five species are recorded, 

 with descriptions and coloured figures, in Buckton's 

 "British Aphides," as feeding on Roses. Of these, 



Fig. 384. Aphis (Sii'ho.nophor.^) ros.e— «, Line showing 

 the natural length. 



Siphnnophora Roace (see Fig. 38-4)> S. rofarum, and 

 S. dirhoda. are often very plentiful on Sweet Briar and 

 on the Cabbage Rose, and also attack the wild Dog Rose. 

 Evergreen Roses seem less liable to be injured by them. 

 The other kinds of Aphides are less evidently hurtful. 

 All of them may be treated in the same way. The reme- 

 dies recommended under Aphides will be found useful. 

 It is desirable to keep the plants as free as possible 

 from these insects, alike because of the sap they ab- 

 stract, and because of their excretions covering the leaves 

 and obstructing the functions of the latter, as well as 

 affording a medium for the growth of dark-coloured 

 Fungi, which still further interfere with the welfare of 

 the plants. The larvfe of a small Moth (Spilonota 

 roborata), and those of a Sawfly (Pwcilosoma candi- 

 datum), bore into the pith of Rose-branches from 

 May to July, of course killing them, and causing the 

 leaves on them to wither. The latter insect has 

 been observed near Oxford by Prof. Westwood. but is, 

 fortunately, rare. The infested branches should be cut 

 off and destroyed while still tenanted by the larv;u. 

 The leaves of Rose-bushes are devoured by numerous 

 insects, mostly Moths and Sawflies. Of the larger Moths, 

 there may be named the Lackey Moth, the Gold-tail 

 Moth and its allies (nee Liparis), the Vapourer Moth 

 {see Orgyia aatiqua), the Bufftip Moth (Pyycera 

 bueepliala), the Winter Moth {Clieiiniit,:}iin brumata), 

 and the Barred Yellow Moth iCidariii fulcata). Each 

 of these, save the last, will be found described under 

 the headings quoted. Cidaria J'lilvata is a Geometer, 

 about lin. in spread of wings, with a slender body. It 

 is yellow, with a broad, brown, angled band crossing the 

 front wings, and a pale, triangular spot at the tip, 

 bordered below by a short, dark streak. The larva; of 

 these moths should be shaken or picked oft' the bushes, 

 collected, and destroyed. Those of the Winter Moth 

 live between leaflets united by threads of silk. The 

 females of this very destructive species are unable to fly, 



