Methyl bromide eradication of the oak wilt fungus in logs. Laboratory and field fumigation
E L Schmidt, M M Ruetze, D W French
Concern over accidental introduction of the oak wilt fungus (Ceratocystis fagacearum) into oak-importing nations has prompted a study supported by the U.S. National Lumber Exporter's Assn. to assess the efficacy of methyl bromide fumigation to eradicate the fungus from logs and lumber. Laboratory and field fumigation trials to develop a reliable and realistic treatment were performed on red and white oaks at the University of Minnesota in 1980. Introduction of pure methyl bromide at a rate of 240 g/m³ of space under a polyethylene cover kept in place for 3 days eradicated the fungus from short log sections at temperatures down to 5°C in laboratory chamber fumigations. Outdoor trials using 2.4 m logs with intact bark reduced the fungus isolation frequency to a fractional percentage of untreated controls, but reducing the duration of fumigation to 2 days was not effective.