Fumigation of lettuce: efficacy and phytotoxicity

Lettuce was fumigated in the laboratory with several commercially available fumigants at various dosages and exposure periods at 4.4 or 24 degree C. Eggs, larvae, and pupae of Trichoplusia ni were exposed in space to fumigants to determine the lowest dosages and periods of exposure which would kill these life stages of the insect. Of the fumigants tested, acetaldehyde, phosphine, ethylene chlorobromide, and ethylene dibromide caused the least amount of damage to lettuce. Phosphine, ethylene chlorobromide, and ethylene dibromide killed the life stages of the cabbage looper at dosages and exposure periods which resulted in a minimum of damage to lettuce.