Effect of Temperature and Commodity on Distribution of CCl4-CS2 (80:20) and EDC-CCl4 (75:25) Applied by Gravity Penetration and Closed Recirculation

Abstract

Gravity penetration and closed recirculation fumigations were conducted in wheat, corn, and sorghum at 45, 65, and 85°F to investigate the effect of temperature and commodity on the distribution of 2 liquid fumigant mixtures. carbon tetrachloride-carbon disulfide (CCI4-CS2, 80:20) and ethylene dichloride-carbon tetrachloride (EDC.CCI4°. 75:25). The fumigations were conducted in 5-ft metal towers each containing 2 bushels of grain. In the gravity fumigations the time required for the passage of a detectable concentration of fumigant through the commodity increased as grain temperatures decreased. Penetration time at each temperature tested was least in com and greatest in sorghum. Concentrations of each component were generally higher in the recirculation fumigations than in the gravity fumigations, particularly at 45°F fumigations. CS2 was less affected by decreased temperatures or changes in commodity than CCl4 or EDC. Comparison of the total component concentrations obtained in each commodity fumigation with the total obtained at each fumigation temperature indicates that the high sorption capacity of sorghum was a more limiting distribution factor than the slower rate of volatilization and penetration resulting from fumigation at 45°F in both gravity and recirculation fumigations.