390 ECONOMIC ENTOMOLOGY 



The "spray gun" may be safely used, however, at a high pressure 

 by the long distance method of spraying in which only the upper side 

 of the leaves becomes wet. 



Bordeaux frequently causes "russetting" of the fruit, and for this 

 reason fruit growers began the use of the summer strength of lime- 

 sulphur. The latter, however, causes a drop of the fruit, and the 

 soluble sulphur-slaked lime-arsenate of lime combination is recom- 

 mended as being free from injurious effects. 



A modification of the 4:40:40 Bordeaux formula is now recom- 

 mended in Nova Scotia for the later sprayings in apple orchards: 

 2 lb. bluestone, finely pulverized; 10 lb. lime; 40 gal. water. 



Many evidences point to the conclusion that in mixtures of Bor- 

 deaux and arsenious compounds the lack of injury to foliage is due to 

 the formation of a copper-arsenide compound rather than to the sup- 

 posed neutralizing action of the lime. 



Soluble Sulphur. — A patent preparation containing about 60 per cent, 

 soluble sulphur and 40 per cent, inert matter. It is used as a substitute 

 for lime and sulphur. Its value has not yet been definitely determined 

 on account of conflicting reports by growers. It has the merit of 

 being easily handled. 



{h) Whale-oil Soap. — Potash whale-oil soap of a good grade, 

 when dissolved in warm water at the rate of 2 lb. to a gallon 

 of water, makes an excellent spray for early spring treatment of or- 

 chards — just before the buds swell. It is also valuable as a summer 

 treatment against aphids and pear psylla, but it should be diluted: 

 I lb. of soap dissolved in 4-6 gal. of warm water. The soap has an 

 invigorating effect on the tree, but the cost prohibits its use in orchards 

 on a large scale. 



Against scale insects on palms, rubber plants, cycads,and oleanders 

 in conservatories whale-oil soap is used at the rate of i lb. to each 

 gallon of water; on ferns however, fir-tree oil or lemon oil (1-15 or 

 20 water) is used as these plants are readily injured by whale-oil soap. 



Soap Solution. — This solution is made by dissolving i lb. of 

 hard soap in 5 gal. of water. It is effective in controlling plant- 

 lice and other sucking insects on house and garden plants. 



The addition of soap solution, 3-5 lb. in 80 gal. of tobacco ex- 

 tract solution, is recommended for plant-lice. 



