404 PEAR GROWING IN CALIFORNIA. 



for aphids it is very valuable, when used at the strength of 1 pound of 

 soap to 5 gallons of water. 



The ordinary form of this soap has to be melted before being used. 

 There is, however, a liquid form on the market which is much more 

 conveniently handled. Fish oils are used in the manufacture of soaps 

 for spraying purposes and may be substituted for whale-oil soap. 



No. 10. Caustic Soda. 



This material can not be considered as an insecticide ; however, it is 

 used frequently in breaking hard water in order that oil emulsion 

 sprays may make perfect emulsions when mixed with water. It also 

 has considerable value in killing moss or lichens on fruit trees. Three 

 pounds of caustic soda to 100 gallons of oil spray will remove moss 

 from pear trees that have been neglected and where it has consequently 

 become abundant. 



No. 11. Distillate Emulsion and Tobacco.* 

 (Government Formula for Pear Thrips.) 



Water 12 gallons 



Whale oil soap 30 pounds 



Distillate (32 to 34 Baume) _ 20 gallons 



The above emulsion is prepared in the ordinary way as a stock solu- 

 tion. For use in the orchard dilute one to twenty parts of water. To 

 every two hundred gallons of this diluted spray add one pint of tobacco 

 extract containing forty per cent nicotine or about three and one half 

 gallons of tobacco extract containing 2f per cent nicotine. 



This spray is especially recommended for pear thrips. 



No. 12. Arsenate of Lead. 



This is the most commonly used arsenical spray in the pear orchard 

 and the commonly used strength is 3 pounds of paste to 50 gallons 

 of water, or 1J pounds of the powdered form of arsenate of lead to 

 50 gallons of water. This amount is sufficient for the control of codling 

 moth, canker worm, tent caterpillar, pear slugs and other larvae which 

 feed upon foliage and fruit. Half of this amount will suffice for the 

 calyx application in spraying for the control of codling moth. 



No. 13. Paris Green. 



In the past this arsenical poison has been very extensively used 

 in spraying for the control of chewing insects, but its use has been 

 superseded by the safer and generally better arsenate of lead. For 

 codling moth and other chewing insects it should be applied at the 

 strength of f pound to 100 gallons of water. On account of the like- 

 lihood of there being more or less soluble arsenic in the Paris green, 

 which may blight the foliage, lime in small quantities should always 

 be added to the spray. Five pounds of stone lime, slaked, to every 

 100 gallons of liquid is sufficient. 



No. 14. Arsenite of Zinc. 



The above is one of the newer arsenical insecticides manufactured 

 by the California Spray Chemical Company of Watsonville. It gives 



"Copied from "Injurious and Beneficial Insects of California," by E. O. Esste. 



186 



