EFFECTS OF FUMIGANTS ON PARENCHYMA VIABILITY IN RED OAK LOG SECTIONS

Fumigation of red oak with methyl bromide has been used successfully t o eradicate the oak wilt fungus from exported veneer logs and prevent enzyme-mediated gray stain in oak lumber. Successful treatment for eit her benefit is directly correlated with death of parenchyma cells thro ughout the sapwood. With the planned phase-out of ozone-depleting meth yl bromide, alternate fumigants require evaluation for their potential application. Sulfuryl fluoride was effective in killing parenchyma in red oak log sections at treatment levels and times required to eradic ate the oak wilt fungus. Methyl iodide: also killed parenchyma with a shorter fumigation period than required for sulfuryl fluoride. Chlorop icrin effected shallow kill of parenchyma beneath the bark, but phosph ine had no phytotoxicity. Sulfuryl fluoride and methyl iodide merit fu rther consideration as methyl bromide replacements for treating raw wo od products.