Notes on scientific research. 119 



Two other hybrids, A' and B', from L. officinalis var. pyrenaica and L. latifolia, 

 correspond to the hybrids A and B described above. The species B' 1 ) resembling more 

 L. pyrenaica and termed L. aurigenara*) differs from hybrid B by the large size of its 

 bracts. The more frequent hybrid A' shows greatly developed bracteoles and an odour 

 of camphor. Side by side with those hybrids there exist various other hybrid forms. 



R. Laubert 3 ) gives a description of the most important diseases of aromatic plants, 

 their origin and symptoms. Amongst the diseases known to occur with roses 4 ), the 

 much-dreaded white rose-blight takes the foremost place. It is caused by a fungus 

 belonging to the JErysibacea. Sphcerotheca pannosa, (Wallr.) Lev. f. rosos, and appears in 

 shape of a white, dust- or flour-like deposit on the leaves, particularly on the tops 

 of the young shoots. On the petioles and the calyces of the blossoms as well as on 

 the fruits the white fur shows a coarse, fluffy appearance. Some rose varieties are 

 attacked by this fungus but slightly, others are known to be very ready victims, e.g., 

 the Crimson Rambler. — Another rose fungus, Phragmidium subcorticosum, (Schrank) 

 Winter (N. 0. Pucciniaceo?) is recognized by its bright orange-red, oblong or round, 

 pulvinate weals occurring in spring on the leaves, their stalks, and on other green 

 parts. In the course of the summer, there may be found on the back side of the 

 leaves small, light orange-yellow dusty pustules, at first only a few, but growing in 

 number, which then turn black and sooty; on the upper side of the leaf, corresponding 

 small yellow or reddish spots appear. Since the leaves attacked by this fungus turn 

 yellow and fall off prematurely, the plants are seriously injured by this disease. The 

 most of the high-class varieties known as remontant roses are readily attacked, in a 

 less degree the tea hybrids and tea roses, whereas climbing and mountain roses are 

 hardly ever afflicted. — The disease known as black spot blight (Sternrusstau) of the 

 rose leaves occurs principally during damp weather and manifests itself on the upper 

 side of the leaves in shape of round brownish-black or violet-black spots which on 

 magnification prove to be composed of small dots and show a finely-radiated, fringed 

 margin. The disease which likewise causes the leaves to fall off prematurely is generated 

 by a fungus sponging upon the green leaves, Actinonema rosce, (Lib.) Fries (N. 0. 

 Sphaerioidacece). Low-growing roses are preferably attacked by this disease. — The 

 Peronospora disease of the roses is, on the whole, not very common, but at times rather 

 dangerous. It can be recognized by small spots on the leaves, which occur irregularly 

 and sporadically and are in the beginning yellowish-grey, later on yellowish-brown. The 

 disease occurs sometimes with roses cultivated under glass and with rose seedlings 

 and is caused by the sponging fungus Peronospora sparsa, Berk. (N. 0. Peronosporacece). 

 Some rose gardeners consider the disease caused by a fungus named Coniothyrum 

 Wemsdorffia? Laubert 5 ) (brown blight) to be the most dangerous of all rose diseases, 

 since at times much damage is caused by this fungus. Early in spring, sporadic big 

 round dark spots get visible on the green bark of the branches, particularly on the 

 buds, which afterwards turn leather-brown to greyish-brown. Later on, the mortified 

 bark splits up and peels off, whereby the woody interior gets visible. When the spot 



r ) As per a paper by J. Gattefosse (Par/km. moderne 14 [1921], 207) this hybrid was found in 1877 in the 

 Pyrenees by Father Sennen and was termed L. Senneni by Abbe Coste. The hybrid L. aurigerana, Mailho, on 

 the other hand, shows more the character of L. latifolia and would correspond to the hybrid A. — 2 ) In the 

 Index Kewensis, a species L. aurigerana, Mailho is enumerated. — 3 ) Deutsche Parf. Ztg. 8 (1922), 1, 17. — 

 *) Cf. Report October 1915, 71. — 5 ) The so-called Carcinoma rosm, recognizable by the abnormal extuberances, 

 is generated not by the fungus Coniothyrum Fuckelii, but by lesions and action of the frost early in March. 

 The fungus is but a secondary phenomenon. Cf. Sorauer, Handhuch der Pflanzenkrankheiten, 1921, vol. I. p. 658. 



