CONTROL OF INSECTS IN TOBACCO 



23 



Figure 16. — Eaves of a tobacco warehouse sealed from the inside with plastic 

 cement. The cement was applied with a calking gun operated by hand. 



where more than usual leakage is anticipated, the dosage should be 

 increased to 20 ounces. Larger dosages are seldom economical. A 

 series of three or four fumigations at intervals of 20 to 45 days is 

 often advantageous. The dosage may then be reduced to 8 to 12 

 ounces per 1,000 cubic feet, with an exposure of 24 to 48 hours. The 

 72-hour exposure, however, gives better penetration. 



In all warehouse fumigation the temperature of the tobacco should 

 be 70° F. or higher. As a rule, therefore, fumigation is satisfactory 

 only in summer or early fall. 



Under favorable conditions warehouse fumigation destroys all 

 stages of the moth and beetle to a depth in the tobacco of 1 to 3 inches, 

 and kills a few of the insects to a depth of 5 to 7 inches. However, 

 some insects deep m the tobacco almost always survive. 



Strong winds during a fumigation may destroy its value: they 

 suck the gas out of a building very quickly. 



Infested tobacco moving into a fumigated warehouse may quickly 

 reinfest the warehouse and nullify benefits of a fumigation. 



CONTROL BY CHAMBER FUMIGATION 



Atmospheric Chamber 



Small chambers equipped for the fumigation of tobacco at atmos- 

 pheric pressure are satisfactory in many tobacco plants. Such cham- 

 bers are usually 2,000 to 5,000 cubic feet in size but are sometimes 

 larger. A chamber may be constructed of wood and tar paper, metal, 

 concrete, or brick. It should be made tight by installing refrigera- 

 tor-type doors closing against a gasket and by covering the walls 

 with asphalt, cement, or heavy paint (fig. 18). 



