Development of tools for detecting, monitoring, and managing brown root rot (caused by Phellius noxius) in the Pacific Islands

Abstract

The brown root rot pathogen (Phellinus noxius) is causing a destructive, mortality-causing disease on diverse tropical trees that are integral to forest ecosystems in the Pacific Islands (e.g., Ann et al. 2002, Brooks 2002, Sahashi et al. 2015, Figure 1). Our previous work indicates that (1) this invasive fungal pathogen is more prevalent and aggressive than previously reported across the Pacific Islands (e.g., Northern Mariana Islands, Federated States of Micronesia, Palau, American Samoa); and (2) multiple genetic groups of this fungal pathogen are present, which indicates that the pathogen can differ across eastern Asia, Australia, and Pacific Islands. To date, P. noxius has not been reported in some U.S. states/territories (e.g., Hawaii, Florida, Puerto Rico) where it represents a major invasive threat based on our bioclimatic models (e.g., Figure 2). Currently, human-associated spread of the pathogen into uninfested areas is a major concern exemplified by possible movement via infected plants, shipping containers, and/or soil associated with equipment/vehicles in the Pacific Islands and other U.S. states/territories. Currently, little or no information is available on (1) identification/detection of P. noxius, (2) brown root rot disease incidence/severity, pathways of spread, and (3) disease management in regions impacted or threatened by this invasive forest pathogen. Here, we present preliminary approaches to develop molecular probes for detecting distinct genetic groups within P. noxius. In addition, we are working to develop DNA-based tools for assessing the effectiveness of management methods for brown root rot disease, which are essential but critically lacking. The DNA-based tools developed from this project will be used to detect and monitor the brown root rot pathogen, while also helping to determine effective treatments to minimize damage from the disease in vulnerable areas within the Pacific Islands. Here, we present preliminary approaches toward developing tools to detect and monitor the soil/rhizosphere inoculum density of invasive P. noxius over time and determine the effects of treatments (e.g., urea, lime, urea + lime, and control) for disease management. In addition, other soil microbiota will be also monitored in association with management treatments.

Citation

Kim, Mee-Sook; Garfinkel, Andrea R.; Cannon, Phil; Klopfenstein, Ned B.; Stewart, Jane E. 2020. Development of tools for detecting, monitoring, and managing brown root rot (caused by Phellius noxius) in the Pacific Islands. In: Reynolds, Gregory J.; Wilhelmi, Nicholas P.; Palacios, Patsy, compilers. Proceeding of the 66th Western International Forest Disease Work Conference; 3-7 June 2019; Estes Park, CO. WIFDWC: www.wifdwc.org. p. 189-192.