A non-pressure method of protection based on hurdle theory to control the spectrum of internal environmental factors which affect the decay of poles in soil contact
A A W Baecker
A field trial was conducted to establish whether superficial barrier linings on poles in soil contact could function as environmental hurdles against the growth of biological agents and thus provide preventative methodology to preclude premature failure of vineyard poles under flood-irrigation. Assessment after 52 weeks exposure to the prevailing conditions and sub-tropical environment showed that open-ended cylindrical linings of biologically inert heat-shrink polyethylene applied to the vertical soil-contact surfaces of Eucalyptus grandis poles unequivocally prevented termite-induced failure of untreated poles, basidiomycete decay of creosote-treated poles and fungal colonisation of CCA-treated poles. The success of the liners in prevention of incipient decay of these poles was explainable on the basis of hurdle theory and was therefore attributed to the ability of the former to control essential growth factors and create internal conditions inimical to the proliferation of decay agents in the poles. Consequently, sub-optimal conditions of Aw, Eh, and nitrogen content were considered to have arisen to function as environmental hurdles which decay agents could not overcome at wood-soil interfaces.