Dosage Applied and Concentration Obtained in the Fumigation of Various Commodities with Methyl Bromide1

Abstract

Results are given of the sorption of methyl bromide by 15 different commodities at three different moisture contents fumigated under intermittent recirculation. The CL-50 was obtained by noting the time required for a concentration loss of 50% of the dosage applied for each commodity. The c. t. (concentration-time factor) was determined by calculating the mean average concentration in mg./l.× time in hours. The rate of sorption of methyl bromide by commodities such as barley, rice, and whole kernel wheat was much less in comparison with commodities such as flax and milo. Correlated mortalities of adult Tribolium confusum Jacquelin duVal and Sitophilus oryzae (L.) are given. Under the conditions of these experiments complete mortality of T. confusum adults could be expected regardless of commodity present if c.t. was greater than 75, or if the concentration remained above 50% of the dosage applied for more than 4 hours (CL-50= > 4 hrs.). Similarly complete mortality of S. oryzae adults could be expected if c.t. was greater than 31 or if the CL-50 was>; 2.5 hours.