382 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY, 



Peat Rock Gardens. By Murray Hornibrook {Garden, April 18, 1915, 

 p. 192, and June 6, p. 295). — The author gives an interesting account of how he 

 was led to substitute slabs of peat for stone in his rock garden, with happy results. 

 He describes the peat slabs employed, which must be large blocks of the top 

 spit full of heather roots to keep them together, and about a yard square. He 

 gives a long list of plants that have succeeded with this method. — H. R. D. 



Phosphate, Availability of, to Various Crops. By H. L. Russell (U.S.A. 

 Exp. Stn., Wisconsin, Rep. 191 3 ; pp. 22 and 23). — Ten kinds of plants were 

 grown under greenhouse conditions, the necessary phosphate being supplied in 

 eight different forms. The plants showed striking differences in their ability to 

 secure and use phosphorus from these various sources. Nine of the ten plants 

 tested responded better to aluminium phosphate than to calcium phosphate, 

 the latter giving inferior results to ferric phosphate in six cases, thus showing the 

 inadequacy of chemical solvents in measuring the availability of different phos- 

 phates. — A. P. 



Pines, A Disease of, caused by Cronartium pyriforme. By Geo. G. Hedgcock 

 and Will. H. Long (U.S.A. Dep. Agr., Bur. PI. Ind., Bull. 247, July 1915, 

 pp. 1-20 ; 1 fig., 2 plates). — Tins fungus produced three kinds of spores, and has 

 two distinct hosts — the Pines and Comandra plants. The process of infection in 

 this rust is similar to that in the White Pine Blister Rust. To control the disease, 

 the destruction of the Comandra plants is suggested, as these serve as a host 

 carrying the asciospores of the fungus. — A. B. 



Plum Trees, On Diseases of. By W. N. C. Belgrave (Ann. Appl. Biol. ii. 

 July 1915, pp. 183-194 ; figs.). — A disease of plums in which the ends of twigs 

 die back was investigated, and a species of Cytospora allied to if not identical 

 with C. leucostoma was isolated. The fungus was studied and inoculation 

 experiments were attempted, but with negative results. — F. J. C. 



Pollination in Orchards (Bestuiving en Vruchtbaarheid van Ooftboomen). 



By M. C. Goethals (Maandblad der Ned. Pomologische Vereeniging te Utrecht, 

 1915). — A general review of some of the literature on pollination in orchards 

 together with a summary of certain investigations in parthenocarpie and 

 development of fruit flowers. This is followed by an account of results 

 obtained by cross- and self-pollination of certain varieties of apple, pear, and 

 cherry. Apple ' Winter Golden Pearmain ' set few fruits when self-pollinated, 

 but set well with ' Cox's Orange Pippin ' and ' Golden Reinette.' ' Cox's Orange 

 Pippin ' set no fruits when selfed (9 flowers only), but set with ' Winter Golden 

 Pearmain' and 'Golden Reinette.' 'Golden Reinette' proved slightly self- 

 fertile, and set well with ' Cox's Orange.' ' Ernst Bosch ' set none when selfed, 

 but set with ' Cox's Pomona.' ' Bellefleur ' proved self -fertile and also set with 

 ' Lentsche Roodge ' and ' Sterappel.' Pear ' Beurre d'Amanlis ' gave no fruit 

 when selfed, but ' Durondeau ' was self-fertile (and under these circumstances 

 seedless, as in our own experiments). — F. J. C. 



Potato, A New Species of Colletotrichum on. By P. J. O'Gara (Mycologia, 

 vii. Jan. 191 5, p. 39). — This fungus attacks stems, mostly underground, 

 of the potato. At times definite dark-brown or black cankers are produced, 

 but often the whole underground stem is involved. The name Colletolrichum 

 solanicolum is suggested for it, and it is said to be common in the Salt Lake 

 Valley, Utah. — F. J. C. 



Potato Diseases, Investigations on. By G. H. Pethybridge (Jour. Dep. Agr, 

 and Tech. Inst. Ireland, xiv. April 1914). — Investigations upon the relative 

 efficiency of powder sprays and liquid sprays against the ordinary potato 

 disease were continued and the conclusion arrived at that the powder sprays 

 were inferior. The result of a single experiment appears to show that spraying 

 with copper salts had no appreciable effect upon the crop (apart from the effect 

 of limiting the disease). Sclerotium disease is, next to " blight " (Phytophthora 

 infestans), the most prevalent potato disease in Ireland. It is due to Sclerotinia 

 sclerotiorum, and is contracted from air-borne fungus spores which are produced 

 by sclerotia which rest in the soil, and is therefore indirectly contracted frqm 

 infected soil. Affected stems fall over prematurely and the yield is seriously 

 diminished, but the tubers are not themselves attacked. No spraying method 

 has been found to check it, but the number of plants affected is greatly reduced 

 by late planting (mid-June) ; this also unfortunately reduces the crop very 

 considerably. " Pink rot " (Phytophthora erythroscptica) has been found to 



