A Southwide Rate Test of Azinphosmethyl (Guthion@) for Cone and Seed Insect Control in Loblolly Pine Seed Orchards

A southwide eficacy test of reduced rates ofa:inphosmethyl (GuthionB)for control of seedand cone insects in loblolly pine seed orchards was conducted in 1992. In each of nine loblolly pine (Pinus taeda L.) seed orchards, an untreated (no protection) check and two ofjivepossible.rates of Guthion@ (1.0, 1.5,2.0, 2.5, or 3.0 lb ai/ac/application) were randomly assigned to three test plots. Insecticide treatments improved first-year conelet survival, second-year cone survival, sound seeds per cone, and sound seeds per conelet at nearly every rate. There was no trend of betterprotection with increasing rates of Guthion@. The 1.0 lb ai/ac rate was as eflcacious as the EPA-registered maximum aerial rate of 3.0 lb ai/ac. Based on these results, orchard managers should consider reduced rates of Guthion@ for operational cone and seed insect control programs. South. J. Appl. For. 22(2):106-l 10. C one and seed insects can severely limit seed production in southern pine seed orchards which produce genetically improved seed for regeneration programs. Important insect pests include the coneworms (Dioryctria spp.) that feed in the NOTE: Manuscript received May 16, 1995, accepted April IS, 1997. A.C. hlangini is the corresponding author and can be reached at (313) 473-7296; Fax: (313) 473-7117; E-mail: amangini/[email protected]. The Southem Seed Orchard Pest Management Subcommittee gratefully acknowledges the supporting organizations assisting in this rate test of Guthion@. These organizations provided the seed orchards and staff required to successfull) complete the test. Orchard managers cooperating were: William Goiness, Bowater, Inc.: Gregory Leach, Champion International Corp.; William Jacobs, Champion International Corp.; Marci Oehler, Container Corp. of America; Leon Dyer. Deltic Farm and Timber Co., Inc.; William Massie, Mississippi Forestry Commission: Larry Miller, Temple-inland Forest Products Corp.; and Davis Gerwig. Wesrvaco Corp. We thank these individuals and their staffs for their essential role in the test. flowers, cones, and stems of pines; and the leaf-footed pine seed bug (Leptoglossus corculus [Say]) and the shieldbacked pine seed bug (Teryra bipunctata [Herrich-Schaffer]) that suck out the contents of developing seeds in cones and conelets (Ebel et al. 1980). Untreated, these insects can destroy as much as 90% of the potential seed crop (Fatzinger et al. 1980). Azinphosmethyl (Guthion@)’ is one of several insecticides registered for cone and seed insect control (Nord et al. 1981) and is extensively used for this purpose (Lowe et al. 1991). Guthion@ was registered by the Environmental Protection Agency (EPA) for use in loblolly (Pinus taeda L.) and slash pine (P. elliottii Engelm.) seed orchards (high-and lo\v-volume ground applications) in 1975 (vanBuijtenen 1981). Since 1980, GuthionB has been applied aerially at a standard rate of 3 lb aiMtreatment with four to six sprays in