Monitoring the concentration of methyl bromide in the treated space during commercial fumigation of logs

Development of sciencebased fumigation schedules for phytosanitary treatments relies on an understanding of the factors which influence the effectiveness of a fumigant under different conditions Understanding the sorption characteristics of a fumigant is a critical step in establishing commercial treatment schedules as this process which involves adsorption and absorption of fumigant molecules influences the concentration of the fumigant remaining in the treated space after fumigation and hence the amount of fumigant available to kill insects We monitored the concentration of methyl bromide during commercial fumigation of three log stacks (average volume 4078 m3) with 120 g/m3 methyl bromide for 13 h under a tarpaulin Pine (Pinus radiata D Don) logs were fumigated at South Port Bluff (New Zealand) during April 2015 Gas samples from the treated space were taken at 05 1 2 3 the treated space indicating that the rest of the fumigant was sorbed These data can now be combined with insect toxicity studies to guide the development of improved commercial treatment schedules to treat log exports from New Zealand