594 JOURNAL OE THE ROYAL HORTICULTURAL SOCIETY. 



used for preparing and applying the washes consisted of an 8 h.p. boiler, 

 three boiling tanks, and two gasoline power-spraying outfits costing 

 altogether £113 10s., and being capable of turning out 2,500 gallons a day. 

 In one experiment the trees were first heavily pruned, the tops being cut 

 out and then three different lots were treated with crude petroleum, lime- 

 sulphur wash, and lime-kerosene wash. The petroleum wash cost 2s. 8d. 

 each tree, the lime-sulphur wash Is. l^d., the kerosene-lime 2s. 6^. 

 The petroleum wash gave the best results with the scale, but the season's 

 fruit crop was lost. With lime-sulphur the mortality of the scale was not 

 so great, but no injury was done to the trees. The kerosene-lime wash 

 caused severe injury to some of the trees, but did little harm to the scale. 

 The following year the whole orchard was sprayed with the lime-sulphur 

 wash at a cost of Is. lOd. each tree. Considerable improvement was 

 noted, although the scale was still present. — C. H. H. 



Shelter-planting". By L. E. Barrett (N.Z. Dept. Agri., Div. Live 

 Stock d- Agr., Bull. 1). — This has special reference to the acacia and 

 eucalyptus, both of which have been found peculiarly suitable for shelter- 

 ing the orchard and farm in the Auckland provincial districts. As in this 

 country, shelter belts of trees have been found of great value throughout 

 New Zealand, especially when farming operations require to be carried 

 out in cold and exposed districts. The raising of seedlings, and the 

 future management of the trees, is interesting reading, and should prove 

 of great value to those who intend going in for the embellishment of their 

 farms and homesteads. — A. D. W. 



Sodium Salts: Effect of Addition to deficient amounts of 

 Potassium on Growth of Plants. By B. L. Hartwell, H. J. Wheeler, 

 and F. R. Pember (U.S.A. Exp. Stn. Rhode I., Rep., 1907, pp. 299-357 ; 

 figs.). — An account of a very extended series of cultivations in sand 

 and water containing deficient and approximately optimum amounts 

 of potassium, and the same with the addition of sodium and of extra 

 calcium. It was found that sodium produced no increase of growth 

 when an optimum amount of potassium was present, but when potassium 

 was deficient sodium gave an increase of growth ; extra calcium did not, 

 on the whole, increase the growth. It is considered that the increase in 

 growth was not in any way due to an increase in the osmotic pressure 

 of the solution, because the addition of extra calcium, magnesium, 

 phosphorus, and nitrogen all failed to cause an increase in growth. A 

 larger amount of potassium was left by the plants in the solution when 

 the potassium in the original nutrient solution was supplemented by 

 sodium ; so that it would appear that sodium is a conserver of potassium. 

 Similar results were obtained in experiments with plants in sand which 

 had been digested with acid. — F. J. C. 



Soil Fertility, Certain Organic Constituents of Soils in 

 Relation to. By 0. Schreiner and H. S. Reed (U.S.A. Dep. Agr., 

 Jliir. of Soils, Bull, 47; November 1907). — The authors consider that 

 one of tfoe chief causes of loss of fertility is due to the accumulation of 

 certain organic compounds which are toxic to plants in the soil. This 



