ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



73 



followed. The quantities of concentrated oil emulsion required to 

 make 100 gallons of diluted spray for various purposes are shown in 

 table 2. 



Table 2. — Dilutions of concentrated oil emulsions required for various strengths of 



spray 





Quantity i of concentrated oil emulsion required to make 

 100 gallons of spray 



Oil in concentrate (percent) 



Dormant 



strength 



for leaf 



roller, 



7-percent 



oil 



Dormant strength for 

 scale, red spider, etc. 



Spring 

 strength 



for 



thrips, 



2-percent 



oil 



Summer 

 strength 



for 



codling 



moth, red 



spider, 



etc. 





4-percent 

 oil 



3-percent 

 oil 



0.8-per- 

 cent oil 



98 



Gallons 



m 



Gallons 



i l A 

 &A 

 6 



Gallons 

 W% 

 3i/4 

 3H 

 351 

 4 

 4H 



Gallons 

 2 



2H 

 2H 

 2% 

 2% 

 3 



Gallons 



% 

 7 A 



95 



90 



7 A 

 l 



80-85 



75 . 



w 



67 : 





All quantities expressed in nearest eighth of a gallon. 



Nicotine 



Nicotine is a very effective contact insecticide for sucking insects, 

 as it not only destroys insects by coming in direct contact with them 

 but also acts as a fumigant in hot weather, killing insects that do not 

 actually come in contact with the spray. This fumigating action is 

 undoubtedly limited to a very short distance, possibly only a fraction 

 of an inch. For this reason it is advisable to spray with nicotine on 

 calm days when the temperature is above 80° F., if possible, and under 

 such conditions the quantity of nicotine recommended for cold weather 

 may be reduced. Nicotine is sold in the form of free nicotine and also 

 in the form of nicotine sulfate (40 percent nicotine), the latter being 

 employed chiefly for orchard spraying. Homemade decoctions are 

 likely to be unreliable. If nicotine sulfate is used alone, 2 or 3 pounds 

 of soap dissolved in water or 1 pound of casein spreader should 

 be added to each 100 gallons of water, to cause the mixture to spread 

 better and penetrate any waxy covering of the insects. The soap 

 should be omitted if the nicotine is added to other insecticides, but 

 the spreader may be used. 



Pyrethrum 



Pyrethrum is finding some use as a contact insecticide. It has 

 little fumigating action, and is thus likely to be less effective than 

 nicotine in hot weather, but in cool weather it is very useful. It 

 should be diluted according to the manufacturer's directions. 



