Envelope treatment to protect softwood timbers from damage by subterranean termites
B C Peters, J W Creffield
Two aboveground field trials were conducted in Australia to determine the effectiveness of envelope treatments of deltamethrin and permethrin for the protection of softwood framing timbers against termite damage. Radiata pine Pinus radiata D.Don and slash pine Pinus elliottii Englem., were treated with Tanalithä T (a novel solvent) to achieve 5-mm-depth envelopes. Details of a field trial against Coptotermes acinaciformis (Froggatt) in the Northern Territory and another in southeast Queensland are presented. At the conclusion of the 12-month field trial in the Northern Territory, all timber specimens had evidence of contact by C. acinaciformis. All envelope treatments protected the test specimens. The novel solvent system appeared to contribute to the overall effectiveness of the deltamethrin and permethrin envelope treatments. Similar results were obtained from the seven-month field trial in southeast Queensland using a different test method against C. acinaciformis and Schedorhinotermes seclusus (Hill). Termites did not cause damage to test specimens via untreated cut ends. Consequently, there appears to be no need to apply a supplementary treatment to exposed cut ends of envelope-treated softwood framing material, with regard to C. acinaciformis or S. seclusus.