Effects of dazomet, metam sodium, and oxamyl on Longidorus populations and loblolly pine seedling production.

摘要

Dazomet, metam sodium, and oxamyl were evaluated for nematode control and production of loblolly pine (Pinus taeda) seedlings in a field infested by Longidorus americanum. Fumigation with dazomet or metam sodium reduced population densities of Longidorus to nondetectable levels early in the growing season but population densities subsequently increased to levels found in untreated control plots by the end of the growing season. Oxamyl had no effect on Longidorus population densities. Seedlings in dazomet-treated plots had significantly greater root and shoot weights than seedlings in control and oxamyl-treated plots within 6 weeks of seed sowing. At the end of the growing season, seedlings in the control and oxamyl plots were very stunted with poorly developed root systems. Seedling shoot length and root collar diameter in dazomet-treated plots averaged 27.4 cm and 4.0 mm, respectively, but in nonfumigated control plots these variables averaged 10.5 and 2.5 mm, respectively. Although dazomet and metam sodium were effective in reducing Longidorus populations for the first seedling crop after fumigation, production of a second crop without additional treatment would be inadvisable based on the increased population of Longidorus by the end of the first growing season..