Characterizing forest root‐ and butt‐rot fungi in Yap, Palau, Pohnpei, Kosrae, Guam and Saipan [Chapter III]
|Authors:||Phil Cannon, Ned B. Klopfenstein, Mee-Sook Kim, Yuko Ota, Norio Sahashi, Robert L. Schlub, Roger Brown, Sara M. Ashiglar, Amy L. Ross-Davis, John W. Hanna|
|Station:||Rocky Mountain Research Station|
|Source:||In: Cannon, Phil. 2014. Forest pathology in Yap, Palau, Pohnpei, Kosrae, Guam and Saipan, Sept. 2013. Trip Report. Vallejo, CA: U.S. Department of Agriculture, Forest Service, Region 5, Forest Health Protection. p. 38-49.|
Ganoderma and Phellinus are two common fungal genera causing butt-rot on trees growing on USA-affiliated islands of the western Pacific. Although these fungi can be quite prevalent, especially in some older mangrove stands, it appears that the majority of infections caused by these fungi leads to severe rotting of the heartwood but do not kill the living tissues of the sapwood, cambium and phloem. Thus, the usual consequence of infection by butt-rot fungi in this part of the world is a loss of structural strength in the bole, but not mortality to the tree. Three notable exceptions were found to this general observation. One is where typhoon winds or storm surges hit mangroves, in which case, butt-rot-afflicted trees are exceptionally prone to breakage and toppling. A second exception is when typhoon-strength winds break or otherwise wound previously healthy trees, subsequently enabling butt-rot fungi to colonize heartwood and spread via root contact to neighboring trees. The third exception is when Phellinus noxius, the cause of brown root rot, is the pathogen affecting a stand. This aggressive pathogen can kill trees outright. Although a number of different butt-rot fungi occur in these islands, not much was known about their classification prior to this trip. In this foray, efforts were made to collect the full range of sporophores (conks, fructifications) that were found in association with butt-rotted trees, and isolations were made of these collected fungi onto the appropriate culture media. When the butt rotter appeared to be P. noxius, efforts were focused to collect samples for isolation. Molecular genetics techniques were then used at the Rocky Mountain Research Station (USDA Forest Service) for preliminary identifications of fungi that had been collected and isolated.