Sulfuryl fluoride and methyl bromide fumigation of hardwood logs of various ages for control of lumber graystain

Fumigation of fresh sugar hackberry and red oak logs with either methyl bromide or sulfuryl fluoride successfully controlled enzyme-mediated sapstain (graystain) in lumber. Water-stored logs have greater propensity for stain and potentially higher moisture levels that might prevent effective fumigation. This study tested stain control by fumigation of logs stored for 2 or 4 weeks. After 2 weeks under a sprinkler, methyl bromide was less effective in stain prevention than sulfuryl fluoride. Although effectiveness of sulfuryl fluoride decreased for logs water-stored for 4 weeks, approximately 80 percent of oak lumber pieces were free of any graystain, while 73 percent of boards cut from control logs from the same tree had moderate to severe stain.