392 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



4 oz. of salt to the gallon. The vessels are placed for three minutes in boiling 

 water, removed to close the openings. The cans or jars are then again heated 

 for two hours. — S. E. W. 



Asparagus : Root Rot. By H. Blin {Rev. Hort. vol. xci. pp. 325, 326 ; 1 fig.). 



— Asparagus attacked by Rhizoctonia violkcea should be isolated by digging a trench 

 round the diseased plants. The soil must be thrown inside the circle. The 

 asparagus plants are dug up, saturated with petroleum, and burnt. The soil is 

 disinfected by injecting carbon bi-sulphide 4 oz., or formalin 2 oz., to the square 

 yard. Good results are also obtained by removing the surface soil and copiously 

 watering with a 0-3 per cent, solution of potassium sulphocarbonate. The 

 following year sprinkle the soil with the same solution before earthing up. After 

 either of these methods, the soil requires nitrogenous manure. 



In non -calcareous soils watering with strong solutions of ferrous sulphate 

 (3 oz. per square yard) is efficacious. — S. E. W. 



Barberry Destruction. By E. C. Stakman (U.S.A. Dep. Agr., Bur. PI. 

 Ind., Farm. Bull. 1058, May 1919, 12 pages; 5 figs.). — This bulletin deals 

 with the great necessity of a campaign for the eradication of the common barberry 

 (Berberis vulgaris), because it forms an intermediate host for the rust of wheat 

 disease. The Department of Agriculture is co-operating with thirteen States 

 in the Upper Mississippi Valley in the destruction of all the bushes of the common 

 barberry in this region. The differences between the Japanese barberry, which 

 does not carry the rust, and the common barberry are shown by diagrams. In 

 addition, the destruction of the Oregon grape bush (Mahonia sp.) is advocated. — 



A. B. 



Bidens, Studies in the Genus. By Earl E. Sherff (Bot. Gaz. vol. lxiv. No. 1, 

 July 191 7 ; pp. 21-41 ; 2 plates). — Ten new species of Bidens are described 

 in detail. These are composite herbs (Heliantheae) , with inconspicuous 

 inflorescences. — R. J. L. 



Blister Canker of Apple Trees : A Physiological and Chemical Study. By Dean 

 H. Rose (Bot. Gaz. vol. lxvii.. No. 2, Feb. 1919, pp. 105-146; with 10 graphs). — 

 In this paper are given the results of a physiological study of the disease known 

 as Illinois or blister canker, which is caused by Nummularia discreta (Schw.) Tul. 



" Microchemical tests indicate, for diseased bark, a partial disintegration 

 of cellulose, a disappearance of cyanogenic glucoside, and a lower content of 

 starch, calcium oxalate, and tannins. 



" Macrochemical analyses show that diseased bark has a higher percentage 

 of dry matter, lipoids, alcohol-water-insoluble residue, and total nitrogen, but 

 a lower percentage of alcohol-water-soluble material than healthy bark. The 

 percentage of carbohydrates in both tissues seems to be about the same. Dif- 

 ferences of tannin content are definite but not large. Sound healthy bark 

 contains more than diseased bark, and diseased bark more than dead bark, from 

 the surface of the canker." 



Diseased bark shows a greater oxidase activity. This is probably due to 

 the combined activity of the oxidases of fungus and host, lower acidity, and 

 possibly to a greater degree of dispersion of the oxidizing agent. The lower 

 tannin content of diseased bark may also be a contributing factor. — R. J. L. 



Bog Water : Colloidal Properties of Bog Water. By George B. Rigg and 

 T. G. Thompson {Bot. Gaz. vol. lxviii. No. 5, Nov. 1919, pp. 367-370). — " It 

 seems clear that the substances in bog water that are precipitated by electro- 

 lytes, and on long standing without electrolytes, and will not dialyse through 

 parchment paper, and although present in considerable quantities, do not 

 appreciably lower the freezing-point of water, are in a colloidal state. Since 

 bog water and preparations from it (for example, the concentrate and the 

 solution of the residue from evaporation) which contain these substances are 

 toxic to Tradescantia cuttings, while preparations that do not contain them 

 (the distillate) are non-toxic, it appears that the toxicity is associated with the 

 matter that is in a colloidal state." 



" The oxidation of the toxic matter to non-toxic matter seems to be a basis 

 of agricultural practice in bringing bog lands into cultivation." — R. J. L. 



Cabbage, Diseases of. By L. L. Harter and L. R. Jones (U.S.A. Bur. PI. 

 Industry, Farm. Bull. 925, Jan. 1918). — Generally speaking, the diseases of 

 the cabbage are best controlled by suitable rotation of crops and the destruction 

 of cruciferous weeds (mustard, charlock, shepherd's purse) in the neighbourhood. 



