Brown root rot disease caused by Phellinus noxius in U.S.-Affiliated Pacific Islands

Phellinus noxius is a fungus that causes brown root rot disease in tree and shrub species of subtropical and tropical regions. It has infected and rapidly killed hundreds of important tree and shrub species in these regions. It is widespread in the Pacific Region including all the island states of American Samoa, the Federated States of Micronesia (Chuuk, Kosrae, Pohnpei, and Yap), the Republic of Palau, the Commonwealth of the Northern Mariana Islands (Islands of Rota and Saipan), and Guam. This report explains how to detect brown root rot disease and its causal pathogen (P. noxius) by recognizing the signs and symptoms of the disease as well as using molecular techniques. It discusses several characteristics of P. noxius that make it such a destructive pathogen in the areas where it occurs and explains how the hot, humid, and sometimes stormy conditions that occur on these islands contribute significantly to disease spread and development. This publication also describes multiple approaches that have been attempted to control this fungus along with science-based information for consideration when trying to manage the pathogen.