KXKRCISES 289 



insects. The variation in the strength of the several brands 

 is such that the recommendations of the makers as to dilu- 

 tion should be followed. Nicotine sulphate (40 per cent 

 solution) is widely recommended for plant lice. A half pint 

 of nicotine sulphate is mixed with 50 gallons of water, 

 to which 3 pounds of soap dissolved in hot water is added. 



Kerosene Emulsion. Kerosene emulsion is used es- 

 pecially as a summer spray for plant lice. 



Formula : 



Hard soap J Ib. 



Kerosene 2 gal. 



Water . 25-50 gal. 



Dissolve the soap in a gallon of soft boiling water and 

 add the kerosene, which should have stood in a warm room 

 to allow it to become as warm as possible without danger 

 from fire. Mix together and stir vigorously for about 

 five minutes or until it becomes creamy white. 



For spraying dormant trees dilute only to 1 5 gallons ; for 

 spraying trees in foliage dilute. to 25 to 50 gallons. 



EXERCISES 



1. In Bordeaux mixture the copper sulphate is the active 

 fungicide. Why is the lime added ? 



2. What classes of orchard pests are controlled by Bor- 

 deaux mixture and dilute lime-sulphur solution ? 



3. What class of poisons must be added for chewing insects? 

 How are they prepared ? 



4. In the control of sucking insects, what sprays are used 

 most commonly? How are they made? 



5. Why is arsenate of lead preferred to Paris green? 



6. Why is it best to use lime with Paris green? 



7. At what period of growth should hellebore be used as a 

 poison ? Why ? 



M. AND H. PLANT PROD. IQ 



