Efficacy of treating live vs
Annosus root disease, caused by Heterobasidion annosum (Fr.) Bref., is a serious problem in California forests (Bega and Smith 1966, Parmeter and others 1978, DeNitto and others 1984, Smith and others 1966). The root disease is widespread and damaging in southern California recreation sites, resulting in conifer mortality which creates hazard trees, depletes vegetative cover and adversely effects wildlife habitat. The disease can easily be prevented by treatment of freshly cut conifer stumps with a registered borate compound. Sporax® is the currently registered material. Although borax (the common name for the active ingredient in Sporax®) is effective in preventing stump infection (Graham 1971), which is the primary infection court of the pathogen, the cost of treating numerous stumps following extensive fire or bark beetle-caused mortality is of concern. The increasing cost of treating freshly-cut conifer stumps with Sporax® to prevent infection by H. annosum has raised some recent questions and concerns as to why stumps created from cutting of dead or fire-killed trees need to be treated with borax. This evaluation provides some background information on the current recommendations, provides results of recent inoculation studies in southern California sites, and discusses suggested changes to the current recommendations for treating stumps of live and dead conifers with Sporax®.