NAPHTHALENE AS A GREENHOUSE FUMIGANT 



11 



Although experiments under ideal conditions in a special fumigation chamber 

 indicate that an exposure of 3 to 5 hours is frequently effective, actual practice 

 shows that the efficiency of naphthalene fumigations is usually less under 

 average greenhouse conditions and an exposure of 6 hours is necessary. 



Figure 1 — Mortality of Common Red Spider When Naphthalene is Vaporized at a 

 Heavy Uniform Rate during the First Half of the Exposure, and at a Light Uniform Rate, 

 or Omitted, During the Last Half of the Exposure as Compared With a Uniform Vapor- 

 ization During the Whole Fumigation. 



Dosage 2 Ounces per 1,000 Cubic Feet. Exposure 6 Hours. 

 Temperature 75° F. Relative Humidity 75 Percent. 

 Waltham, Massachusetts. 1935. 



4 5 



EXPOSURE IN HOURS 



A — 1 ounce each hour for 3 hours — none for 3 hours 



B — % ounce each hour for 3 hours — J| ounce each hour for 3 hours 



C — l A ounce each hour for 6 hours 



D — Commercially effective mortality from 1 fumigation 



