66 INSECTA 



SPRAYS AND SPRAYING 



There are three classes of pests which may be combated by 

 spraying: fungi, sucking insects, and biting insects. For 

 spraying fungi, Bordeaux mixture has long been used with suc- 

 cess. The only objection to it is on account of its tendency to 

 injure tender foliage and the delicate skin of young fruit. On 

 account of this, lime sulphur is often used as a fungicide in spray- 

 ing. After July 1 the skin of apples is smoother and firmer and 

 not so easil}^ injured by the Bordeaux. Bordeaux is recom- 

 mended also for apple scab, the spray to be applied just before 

 the blossoms open. Bordeaux is a fungicide only, having no 

 effect upon insects, while lime sulphur acts as both a fungicide 

 and a contact insecticide. 



Insects having sucking mouth-parts are not affected by ar- 

 senic sprays, since poison placed upon the surface of the plant 

 is not taken into the stomach with the food. These insects 

 must be killed by contact insecticides. 



Biting insects may be poisoned by arsenic sprays, since they 

 chew and swallow the food. 



Formulas for Spraying Mixtures 



Fungicides. 



Bordeaux mixture: 



Quick lime, 3 to 6 pounds. . 

 Copper sulphate, 3 to 6 pounds. 

 Water, 50 gallons. 

 Dissolve the copper sulphate in water in an earthen jar or 

 wooden pail and dilute to about thirty gallons. Slake the lime, 

 which must not be partially air-slaked, and add to it twenty 

 gallons of water. Now mix the two solutions thoroughly and 

 strain through a A\dre-cloth strainer into the spray tank. Two 

 pounds of arsenate of lead may be added to this mixture if 

 wanted for an insecticide. 



Lime sulphur (for spraying against San Jose scale) : 

 Commercial lime sulphur, 1 gal. 

 Water, 8 to 12 gal. 

 For summer spraying of apples: 

 Lime sulphur, 1 gal. 

 Water, 30 to 40 gal. 



