NAPHTHALENE AS A GREENHOUSE FUMIGANT 27 



Operating Cost 



Maximum Minimum 



Naphthalene, 3 or 2 ozs. per 1,000 cu. ft.: 



3 ozs. per 1,000 cu. ft. — 180 ozs. or 11 % lbs. at 10c $1 . 125 



2 ozs. per 1,000 cu. ft. — 120 ozs. or 7^ lbs. at 10c $0.75 



Fuel for stoves: 



2 gals, kerosene at 17c 34 .34 



Additional fuel for heat: 



Cold weather — 37 gals, oil at 6c 2 . 22 



Cool weather — 12 Y> gals, oil at 6c .... .75 



Additional labor: 



6 hours at 30c 1 . 80 None 



Total . . $5,485 $1.84 



PROCEDURE FOR FUMIGATING WITH NAPHTHALENE 



Choose the time for fumigating according to the weather. When it is cool 

 start the fumigation about 9 a. m. on cloudy days; when it is warm, start 

 about 4 p. m. Do not fumigate on windy days. 



Remove susceptible varieties of plants from the greenhouse whenever prac- 

 ticable. 



Water all potted plants, wet the walks, and be sure that soil in the benches 

 is moist, thus raising the relative humidity to about 80 percent as determined 

 from a hygrometer or a psychrometer. 



Close ventilators and stop drafts through broken or loose glass. 



Raise temperature to 75° to 80° F., as determined from an accurate ther- 

 mometer, and adjust heating equipment to maintain that temperature. 



Determine the cubical contents of the house by multiplying the length by 

 the width by the average height. Supply a stove for each 7,000 cubic feet in a 

 large house, or for each 5,000 cubic feet in a small house, placing them just 

 above the top of the plants. 



Determine the amount of naphthalene crystals necessary for treatment at 

 the rate of 2 or 3 ounces per 1,000 cubic feet, depending upon the tightness of 

 the house. Determine the proportionate amount for each stove and divide 

 this by 6 to give the amount for each stove for each hour. Mark this hourly 

 dosage in a glass or cup which can be conveniently used as a measure. 



Example: A house 200 feet long, 40 feet wide, 10 feet average height, con- 

 tains 80,000 cubic feet. At the rate of 1 stove for each 7,000 cubic feet, use 

 12 stoves placed about 15 feet apart. At the rate of 3 ounces of naphthalene 

 per 1,000 cubic feet, 20 ounces per stove (80 x 3 = 240 -*-12) is necessary and 

 should be divided at the rate of 3 3^ ounces (20 4-6) per stove per hour for 6 hours. 



Light stoves and adjust wicks to a low flame, being sure that they do not 

 blaze up in one corner. 



Put one hourly dosage of naphthalene in each pan. 



After one hour add another hourly quota to each pan, and if necessary adjust 

 the flame of the lamp by raising the wick if some naphthalene remains or by 

 lowering it if the material has vaporized before the required time. Repeat this 

 operation each hour until six hourly doses have been vaporized. 



If the melted naphthalene should boil or should vaporize in less than half 



