FUNGITOXICITY OF SULFURYL FLUORIDE TO CERATOCYSTIS-FAGACEARUM IN-VITRO AND IN WILTED RED OAK LOG SECTIONS

The European Union requires imported red oak logs to be fumigated with methyl bromide to eradicate the oak wilt fungus, Ceratocystis fagacea rum. The restriction of methyl bromide would threaten the export of oa k, as other fumigants have not been evaluated. Sulfuryl fluoride penet rates wood and has been used extensively for insect control, but fungi cidal effects are unknown. The effect of sulfuryl fluoride exposure on 10-day-old C. fagacearum cultures was tested in a closed circuit fumi gation chamber at concentrations of 16, 40, 60, 80, 100, and 120 g/m(3 ) for 24 and 48 h. Rates of 80 g/m(3) for 48 h and 120 g/m(3) for 24 h rendered cultures unable to grow. When stained with Janus Green B, bo th mycelia and conidia were nonviable. End-sealed log sections from wi lted red oak trees were fumigated at 160, 220, and 280 g/m(3) for 72 h . Eradication of C. fagacearum from red oak log sections was achieved after exposure to 280 g/m(3) for 72 h. (concentration x time product = 18,530 g h/m(3)). Graphium, Verticillium, and Paecilomyces spp. (also isolated initially) were eradicated after the 18,530 g h/m(3) treatme nt. This is the first report of fungitoxicity of sulfuryl fluoride.