Comparison of performance of wood extractives as preservatives in field tests against termites and decay in the USA and Pakistan

Abstract

Increasing environmental regulations have limited the use of certain broad spectrum synthetic pesticides as wood preservatives creating a need for more environmentally benign wood preservative systems. Biocidal compounds from natural products have been proposed as alternatives to commercial wood preservatives, but field data from long term performance testing is lacking. To investigate long term performance of wood extractives, stakes and blocks of southern pine (SP) and cottonwood (CW) were treated with heartwood extractives of four durable wood species commonly used in Pakistan. Treated samples were exposed to decay and termites using two American Wood Protection Association (AWPA) standard field evaluation methods: AWPA E26 and AWPA E7 in Mississippi (USA) and Lahore (Pakistan). After one year of exposure in Pakistan, solvent treated SP and CW test samples were severely destroyed by Heterotermes indicola in both tests. In both tests, wood treated with extractives from Pinus roxburghii and Cedrus deodara incurred higher levels of termite attack at both sites compared to their extractives + oil (Linseed). Decay ratings for Dalbergia sissoo, Cedrus deodara, and Pinus roxburghii treated wood were also lower than other treatments at both sites. Positive control E7 stakes treated with Cu-NAP and E26 blocks treated with borate showed slight attack by termites and decay at the Lahore site, however there was no attack observed at the Mississippi site. Solid heartwood P. roxburghii and C. deodara E7 stakes had average decay ratings of less than 5 at the Lahore site. However, there was no attack observed on E7 stakes at the Mississippi site except in P. roxburghii. There was higher termite pressure by Heterotermes indicola in Pakistan compared to Reticulitermes flavipes at the Mississippi site. Lower decay or termite ratings were observed on wood treated with extractives in combination with linseed oil at either site after 12 months.

Citation

Hassan, Babar; Ahmed, Sohail; Mankowski, Mark; Kirker, Grant. 2017. Comparison of performance of wood extractives as preservatives in field tests against termites and decay in the USA and Pakistan. In: Proceedings, one hundred thirteenth annual meeting of the American wood protection association. Las Vegas, NV: April 9-11. 9 p.