IODOMETHANE AS A METHYL-BROMIDE ALTERNATIVE FOR PREVENTION OF NON-MICROBIAL ENZYME STAIN (GRAY STAIN) OF HARDWOODS BY LOG FUMIGATION

Non-microbial discolorations of sapwood in hardwoods causes large econ omic loss. One method of prevention is to fumigate fresh logs with met hyl bromide. Iodomethane has been suggested as a substitute for ozone- depleting methyl bromide in agricultural applications, but its ability to prevent enzyme-mediated stain in wood has not been demonstrated. S ugar hackberry and red oak logs were fumigated under plastic tarps wit h iodomethane and processed into lumber. Good control of gray stain wa s noted for hackberry but not for red oak. Iodomethane does kill paren chyma in the sapwood, but is not an adequate substitute for methyl bro mide for stain prevention in these hardwoods at similar concentration x time product (CT) values (approximately 18,000 g-hr.). Further trial s are needed to determine efficacy of methyl iodide at higher CT value s (equivalent molal basis to methyl bromide). Reduction of log fumigat ion time from 72 to 48 hours with methyl bromide does not provide adeq uate prevention of sapwood discolorations in these hardwoods.