Brown Root Disease in Rubber

Phellinus noxius: the third major root disease in Malaysian rubber. Slower spread than white or red root but persistent in old estate blocks. Recognition and destroy protocol.

Brown root disease (Phellinus noxius) is the third of Malaysia’s three major rubber root diseases. It is less common than white or red root but persists in old estate blocks and re-emerges at replanting. Slower spread but similar cordon-and-destroy management.

Cause

• Old stumps in replanting blocks
• Long-cycle estates with multiple rubber rotations
• Adjacent forest edges

Effect

Stage	Above-ground symptom	Below-ground symptom
Early	None visible	Dark brown crust with soil particles firmly encrusted on the root surface
Mid	Yellowing, thinning canopy	Crust thickens, root rot
Late	Wilting, latex drop, tree death	Roots destroyed

The key diagnostic is the soil-encrusted crust on the roots that resists brushing off.

Satellite signals

Same expanding-cluster pattern as white and red root, but slower (0.3 to 0.5 m/year).

Action

1. Confirm at the collar

   Dark brown crust with adhering soil that cannot be brushed off confirms Phellinus noxius.

2. Cordon and destroy

   Same protocol as white root.

3. Follow up

   3-month cadence for 2 years.

Recommended alert settings

Same as white root.

Related

• White root disease
• Red root disease
• Field Walk Protocol