Effect of Methyl Bromide Treatments on Several Species of Conifer Seed

Imported seed of Scotch pine, mugo pine, Norway spruce, and white spruce were subjected to several fumigation treatments using methyl bromide. Upon entry into the U.S., seed samples were taken and moisture contents adjusted to 5, 10, and 15 percent. Treatments were standard dosages of methyl bromide, with and without vacuum, and with either one-hour or 24-hour aeration periods. Results showed that seed should have a low moisture content before fumigation. Also, a 24-hour aeration period is recommended. Unfumigated seed with a 15 percent moisture content had a significant reduction in germination at the end of three weeks. Importers and exporters of tree seed should know the moisture content of their seed and make adjustments, if needed, prior to shipment and fumigation to insure that moisture contents are low.