158 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Rhododendrons. By E. J. P. Magor {Gard. Chron. Jan. n, 1919, p. 15). — ' 



Among notes on other plants grown at Lamellen, N. Cornwall, are descriptions 

 and records ol flowering of many new Chinese and some hybrid Rhododendrons. 



E.A.B. 



Root-fungi of Orchids {Orch. Rev. xxvi. pp. 4-7, 29-31, 55, 135). — A summary 

 of the question of the Mycorrhiza of orchids and method of culture, by Bernard 

 and others, with a recipe of the materials used, also an account of the 

 recent method of inducing the germination of orchid seeds by means of a nutrient 

 solution. The highly specialized seeds of Orchis seem to contain an insufficient 

 store of nutriment to carry them over the initial stages of germination, and have 

 contracted a habit of relying on the assistance of the root fungi. The possibility 

 of supplying the deficiency by means of a nutrient fluid affords interesting 

 possibilities for the future. — R. A . R. 



Roses, Diseases of. By L. M. Massey (U.S.A. Hort. Soc, Mass. Trans. 

 1918, pp. 81-101 ; plates). — Black spot (due to Diplocarpon rosae, of which 

 Actinonema rosae is a stage) is started by inoculation from diseased fallen leaves 

 (which should be collected and burned), and Bordeaux mixture or lead arsenate 

 (10 parts of powder) — sulphur (90 parts finely ground) mixture applied dry, are 

 recommended as sprays. Powdery mildew (Sphaerotheca pannosa) was also kept 

 in check by the lead arsenate-sulphur dust spray. Crown-canker is a disease 

 caused by the fungus Cylindrocladium scoparium. The disease starts by a slight 

 discoloration of the bark, the colour deepens to black, and the tissues appear water- 

 soaked. Later, these spots encircle the shoot, and cracks are produced extending 

 to the wood, the stem swells at and above this spot, and the cracks deepen and 

 become more evident. The tree generally lingers for a long time, producing 

 poor and few blossoms. No control measures have so far been devised. Crown 

 gall, due to Bacterium tumefaciens, is frequent on roses, but no cure is known. 

 Prevent infection of soil by planting only healthy plants. — F. J. C, 



Roses, The Use of Commercial Fertilizers in Growing. By F. W. Muncie 

 (U.S.A. Exp. Sin. Illinois, Bull. 196, Feb. 1917, pp. 511-564 ; 1 illus., 24 tables, 

 37 figs.). — Describes experiments in growing first-year roses in a greenhouse 

 during 1910-15. The varieties grown were ' Bride' and ' Killarney,' half the 

 plants of each being own-root stock and half being grafted. 



Grafted stock more than paid for the increase in initial cost by its larger 

 production during the first year. 



No benefit was obtained from the use of potassium sulphate. 



A definite relation was found to exist between the variation in hours of 

 sunshine and the subsequent production of flowers. 



A decrease in production resulted from mixing ground limestone with the 

 soil, whether or not acid phosphate had been added. If needed for sweetening 

 the soil, and for preventing the growth of algae, make a top-dressing of finely 

 ground limestone at the rate of 10 lb. per 100 square feet of bench space. 



Acid phosphate gave a greatly increased production with all types used 

 in the experiment except grafted ' Brides.' Use generous quantities in the soil, 

 i.e. at the rate of 4 to 8 tons to the acre in the field, or in a compost with soil at 

 the rate of 40 to 80 lb. per 100 cubic feet of soil. 



Keep up the nitrogen content of the soil by turning under green or farm 

 manure before use. Liquid manure containing nitrogen should be used sparingly 

 — only during sunshiny weather and chiefly during periods of heavy production. 

 Dried blood in amounts exceeding 8 lb. per 100 sq. feet of bench space was 

 found to cause a decrease in production with all except own-root * Killarneys.' 



Brown silt loam, the type of soil at the Illinois Station, will not produce a 

 maximum crop of roses without fertilization. — F. G. A. 



Rubber Trees, Fungus Disease of (U shdina zonata (Lev.) Sacc. on Heveabrasilien- 

 sis). By A. Sharpies, A.R.C.S., D.I.C. (Ann. Appl. Biol. vol. iv. No. 4, March 

 1918 ; pp. 153-178 ; figs.). — Contains a history of pests and diseases in rubber 

 plantations. Experiments in inoculation with U . zonata ; sources and means 

 of infection : treatment, and outlines for future research. — R. C. S. R. 



Rubus lllecebrosus Focke. By R. A. Rolfe (Bot. Mag. t 8704 ; April 191 7). 

 — Native of Japan. The Strawberry-Raspberry, a Rubus with a herbaceous stem, 

 attaining a height of about eight inches in summer and dying down to the ground 

 in winter. Its fruits are large and scarlet, and flowers white. It is quite hardy 

 and grows well in loamy soil, and is easily propagated by seeds or by division 

 of the old plants. R. illecebrosus was for a long time treated as an alpine form 

 of R. rosacfolius despite its herbaceous habit. — L. C. E. 



