No known vector.

A dark brown mycelial mat or sleeve on the surface of the roots and up to the base of the stem is used reliably for field identification of P. noxius.

Soil is scraped away around the collar and the main roots and the distinctive mycelial sleeve is often present. Focus on wilted and dead plants.

Similar to those caused by other root rot pathogens: slow plant growth, yellowing and wilting of leaves, defoliation, branch dieback, and plant death.

Morphological:

A. Surface sterilized diseased root tissues are plated on potato dextrose agar amended with ampicillin and benomyl or Chang (1995) medium.

B. The cultural characteristics of the fungus are examined and compared to photos in Ann et al. (2002) and Brooks et al. (2002).

C. The Key of the Polyporaceae described by Cunningham (1965) is then used for identification of the fungus.

Symptoms of brown root rot are similar to those caused by other root rot pathogens.

Phellinus noxius may be confused with P. lamaensis, not known to occur in the United States.

The closely related Phellinus lamaensis (Murr.) Heim can be distinguished from Phellinus noxius by hymenial setae and narrow (less than 7¼ mm diameter) setal hyphae. The two species attack some of the same hosts.

Chang (1995) developed a selective medium for P. noxius using malt extract agar as a basal medium amended with benomyl, dicloran, ampicillin, and gallic acid. Tergitol NP-7 was added for isolation from soil.

Molecular: A PCR to detect P. noxius was developed in Taiwan to detect specific regions of the ITS (Tsai et al., 2007).

Baiting out the pathogen by placing sticks of a susceptible host in the soil and retrieving for laboratory examination after 3 weeks is also conducted, particularly in virgin forests to detect parasites on the root system of wild trees.