Abstract

S. A. Enebak, T. E. Starkey, M. Quicke

For many years, forest-tree nurseries in the United States have relied on methyl bromide (MBr) soil fumigation to control weeds, pathogenic fungi, insects and nematodes. However, due to the concern over ozone depletion in the stratosphere, finding a soil fumigant alternative for MBr has been a priority for the forest nursery industry since 1991. A large-scale study comparing seven fumigants using operational application techniques and normal nursery management practices over two growing seasons was installed in two forest-tree nurseries in Georgia: the Plum Creek Nursery in Jesup, and the Rayonier Nursery in Glennville. Control of weeds, nematodes, and soilborne fungi was dependent upon the soil fumigant used and cropping season. By the end of the second growing season in 2008, there were no significant differences in seedling densities for any of the soil fumigants tested, as all soil fumigants were similar to MBr. While many seedling producers would prefer to use MBr to produce forest-tree seedlings in perpetuity, each nursery manager will need to identify the best alternative for their nursery conditions. Based on these 2 year trials, the soil fumigants with 100% chloropicrin and Pic + at 336 kg/ha (300 lbs/a) appear to be suitable alternatives for MBr in controlling forest-nursery pests and producing high quality seedlings at the Jesup and Glennville, GA Nurseries.