DIFFUSION OF DISODIUM OCTABORATE TETRAHYDRATE INTO SOUTHERN YELLOW PINE TO CONTROL WOOD-INFESTING BEETLES

Abstract:
Emulsions of chemicals applied to the surface of seasoned softwoods results in a residue 1-3 mm below the surface, and can provide control of wood-infesting beetles. Borate compounds can be delivered to wood surfaces in sufficient quantities for subsequent diffusion to depths below the surface. The penetration of boron depends on the presence of free water in the wood cells. Penetration at 24 h and 6 wk of a 10% (AI) dilution of disodium octaborate tetrahydrate (DOT) into southern yellow pine (Pinus sp.) blocks was investigated following one and two .applications and exposure to 85% and 50% RH environments. DOT treated and untreated wood was sectioned (50 um per slice) with a microtome from the treated surface to five depths: 50,950, 2000, 2500, and 3000 um, and analyzed for boron. The boron content of each wood slice (ppm) was performed by a dry ashing procedure using inductively coupled plasma spectrometer (ICP). Factors influencing penetration of DOT into the southern yellow pine blocks were maximum application volume, 16-19% initial WMC, and exposure to a 85% RH environment following treatment. Two applications of 10% DOT to wood with 16-18% WMC, followed by 6 wk in a 85% RH environment resulted in greater amounts of boron detected at the 3000 um depth than did other treatments. The results of the evaluations reported here indicate that the amount of boron detected on and below the wood surface, to the depth of approximately 2 mm, should provide protection from wood infesting beetles.