June 2005. Palau reported the death of two trees, Macaranga carolinensis and Terminalia catappa. Both trees show the same sign: brown-black decay progressing from the base up the trunk. This was followed in the case of M carolinensis by wilting, then death of leaves. The tree appears to be dead. The T catappa does not show symptoms yet, but the decay has progressed about 1 meter up the trunk. One exposed roots of the M carolinensis shows similar progress ofthe disease. Three nearby M carolinensis trees show no signs of disease, and other nearby trees are also unaffected.

An infected Delonix regia from Guam was sent for comparison (lower, right).

The trees are infected by the fungus, Phellinus species. In terms of a “most likely suspect” looking at the pest list for Palau, There are two species recorded from Palau: Phellinus gilvus and Phellinus lamaënsis. See: http://www2.ctahr.hawaii.edu/adap2/ascc_landgrant/Dr_Brooks/TechRepNo37.pdf and
http://www2.ctahr.hawaii.edu/adap2/ascc_landgrant/Dr_Brooks/BrochureNo4.pdf

Phellinus can be a real problem in certain situations because it infects so many host species. A good diagram of the life cycle can be found here: http://www.apsnet.org/pd/pdfs/2002/0524-01F.pdf

It is also not an easy disease to control as the fungus lives in the soil and spreads by root-to-root contact. There is some interesting work done by a Taiwanese group on control of Phellinus using calcium carbonate and urea.