PEAR GROWING IN CALIFORNIA. 405 



splendid results in killiiis: certain insects which are more or less re- 

 sistant to arsenate of lead poisoning, as well as all those for which 

 the arsenate of lead is used. This is a less stable compound than 

 arsenate of lead and for that reason considerable damage has been 

 done to the foliage and fruit of trees to which it has been applied. It 

 is recommended only for the calyx application for codling moth on 

 apple trees and no doubt would also be effective in the case of pears. 



No. 15. Bordeaux Mixture. 



Coppor suli)hate 20 pouuds 



Stone lime (unslaked i 20 pounds 



Water 200 gallons 



Preparation. 



The copper sulphate is first dissolved by suspending the weighed 

 amount in a sack in a sufficient quantity of water. The lime is slaked 

 in an equal amount of water and the two liquids containing the dis- 

 solved materials poured together into the spray tank, where the agitator 

 Avill keep the liquid properly mixed. Bordeaux may now be purchased 

 in the form of a paste ready for dilution with water. The convenience 

 of this form, though it is more expensive than the home-made product, 

 is fast making it popular. Bordeaux is one of the older fungicides 

 and is by many rated as the best that has ever been discovered for 

 general fungicidal purposes. 



No. 16. Lime-Sulphur — Self-Boiled. 



Stone lime S pounds 



Sulphur S pounds 



Water __ 50 gallons 



Preparation. 



The preparation differs from that of the home-made, boiled lime- 

 sulphur in that only the heat of the lime, which is generated during 

 the slaking process, is utilized. It is made in a barrel or tank, Avhieh 

 may be covered tightly to retain the heat for about 15 or 20 minutes, 

 when a slight amount of sulphur and lime will have combined. It 

 is diluted with cold water, after being strained. 



In some of the states to the east the self-boiled lime-sulphur alone 

 or in combination with arsenate of lead has been used very successfully 

 in the control of scab but has not been generally recommended under 

 California conditions. 



No. 17. Bichloride of Mercury. 



Corrosive sublimate, (bichloride of mercury), is used extensively 

 in pear blight work for disinfecting tools and wounds made in the 

 removal of blight from affected • trees. It may be purchased from 

 druggists in the form of tablets, one tablet dissolved in a pint of water 

 making a 1 to 1000 solution. 



No. 18. Formalin. 



Formalin is sometimes used in place of bichloride of mercury as 

 a disinfectant, but is not recommended for disinfection work in con- 

 nection with pear blight control. 



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