532 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Soluble Humus, th9 Effect of Removing from a Soil. By William Weir 

 (Jour. Agr. Sci. vii. Part 2, pp. 246-253; Sept. 1915). — It has commonly been 

 assumed that that portionof the humus of a soil which is soluble in dilute alkaline 

 solutions plays, by reason of its solubility, an important part in plant nutrition. 

 The author has, however, been able to find only one recorded experiment (Gran- 

 deau, 1872) designed to establish the truth or otherwise of the assumption. 

 He has accordingly repeated Grandeau's experiment during two seasons on a 

 larger scale. The soils were first washed with dilute hydrochloric acid to remove 

 bases and then repeatedly extracted with dilute soda, whereby humus containing 

 approximately 40 per cent, of the total nitrogen was removed. Four successive 

 crops (wheat, mustard, rye, and mustard) were grown in the untreated and 

 extracted soils respectively, and approximately equal total yields of dry matter 

 and of nitrogen were obtained from the two series. Afterwards laboratory 

 experiments were made to determine the rate of production of nitrate and of 

 ammonia in untreated and in extracted soil, and it was found that removal of 

 soluble humus increased the number of bacteria and the amount of ammonia 

 but diminished the nitrate, the sum of ammonia and nitrate being usually less 

 than in untreated soil. Russell and Hutchinson have shown that in uncropped 

 soil the accumulation of nitrate and ammonia is stopped when a certain stage is 

 reached, but in a cropped soil they are being constantly removed by the growing 

 plant. Hence the conditions of the above-described vegetation and laboratory 

 experiments are not the same, and therefore the results obtained from them are 

 not inconsistent. — /. E. W. E. H. 



Spruce, Two Rust Diseases of. By A. W. Borthwick and M. Wilson (Notes 

 Roy. Bot. Gard. Edinburgh, xli. p. 65, Apr. 1915 ; plate). — The uredo and 

 teleutospore stages of Chrysomyxa Rhododendri were discovered on Rhododendron 

 hirsutum in Scotland ; it also occurs on R. ferrugineum and R. dauricum. The 

 alternate stage occurs on the spruce, and has been known as Aecidium abietinum. 

 Uredo Rhododendri is the uredospore stage. C. Abietis occurs on the needles 

 also, but goes through all its stages on the spruce ; attacked leaves turn yellow 

 and fall. — F. J. C. 



Stocks (Matthiola), Doubles in. By E. R. Saunders (Jour. Gen. v. pp. 137-143; 

 Dec. 1915). — The authoress reports the result of selecting the most vigorous 

 and so on down to the least vigorous of the seedlings, and finds the percentage 

 of doubles greater in the former than in the latter. She concludes that uncon- 

 scious selection of this kind has led seedsmen to attribute a larger percentage 

 of doubleness to their strains than actually occurs. — F. J. C. 



Stone Fruits, Fungoid Diseases of. By G. P. Darnell-Smith and E. 

 Mackinnon (Agr. Gaz. N.S.W. vol. xxvi. pp. 589-598; 11 figs.). — Peach Leaf 

 Curl is caused by the fungus Exoascus deformans, which attacks the fruit as 

 well as the leaves. To prevent the attack of this pest, spray with Bordeaux 

 mixture just before the buds open. 



Brown Rot is the cause of much damage to peaches, plums, cherries, and 

 nectarines. It is due to the fungi Sclerotinia cinerea and S. fructigena. The 

 fungus not only attacks the fruit but also the branches, producing canker. To 

 prevent the ravages of this disease, spray with Bordeaux mixture before the 

 buds open, with lime-sulphur three weeks after the petals have fallen, and a 

 third time with lime-sulphur about a month before the fruit ripens. Lead 

 arsenate may be added to the spraying solution to destroy leaf-eating insects. 

 Prune out all dead wood and burn all mummied fruit. — 5. E. W. 



Strawberries, To Force. By M. Bultel (Jour. Soc. Nat. Hort. Fr. March 1914, 

 p. 163 ; figs.). — Further experiments seem to prove conclusively that there is 

 really nothing to choose in the matter of efncacity between the two processes of 

 etherization and of immersion in hot water in forcing strawberries, and that both 

 have a marked effect in hastening the maturity of the crop. Comparative tables 

 of the results of experiments are here given. — M. L. H. 



Strawberry, New (Le Jard. vol. xxix. p. 237 ; 1 fig.). — ' Mme. Henri Leduc' is a 

 large round strawberry, resulting from a cross between ' Monseigneur Fournier ' 

 and ' Noble.' The fruit is dark red and is sweet. — S. E. W. 



Strawberry Pests. By W. W. Froggatt (Agr. Gaz. N.S.W. vol. xxvi. pp. 133- 

 137; 1 plate). — The Flower Weevil (Anthonomus signatus) lays its eggs in 

 the flower-buds. The larvae devour the pollen and prevent the formation 

 of fruit. The Strawberry Root Weevil (Otiorhynchus ovatus) does much damage 

 in British Columbia by eating-off the roots of the plants. The beetles may 

 be trapped by placing flat pieces of board in the beds. The Crown Weevil 



