Cause
- Old rubber stumps left in the ground at replanting (primary reservoir)
- Adjacent forest or old rubber at block boundaries
- Root contact with an infected neighbor
- Waterlogging weakens tree defenses and accelerates infection
- Wound sites on roots from ploughing or machinery
Effect
The disease spreads at 1 to 3 m per year from tree to tree. A focus that starts with one tree grows to 5 to 10 dead trees within 2 years if not stopped.
Satellite signals
Cross-check any expanding cluster against the rubber ecosystems baseline to distinguish white root from wintering.
Action
1
Confirm at the collar
Scrape topsoil at the collar of the suspect tree. White fan-shaped rhizomorphs on the root surface confirm Rigidoporus microporus. If unsure, contact the Malaysian Rubber Board for confirmation.
2
Cordon isolation trench
Dig an isolation trench (60 cm deep, 30 cm wide) around the focus, at least 2 m outside the last infected tree. This severs root contact and stops horizontal spread.
3
Inspect every neighbor within 5 m
Scrape collar of every tree within 5 m in all directions from the infected focus. Root grafts spread the pathogen invisibly.
4
Fell, uproot, and burn infected trees
Fell all confirmed and probable trees. Uproot the stumps (do not leave them in the ground; they are the primary reservoir). Burn all root material on site.
5
Apply fungicide to remaining neighbors
Drench root collar of neighbors within 5 m with tridemorph (Calixin) or triadimefon (Bayleton) as per MRB recommendation. Repeat every 6 months for 2 years.
6
Sanitize tools
Wash all tools with fungicide or bleach between blocks. Never move root material or stump wood off-site.
7
Follow up
Re-inspect the treated zone every 3 months for 2 years. Expanding-focus surveillance is the only way to catch missed cases.
Recommended alert settings
Related
- Red root disease
- Brown root disease
- Field Walk Protocol (root-collar inspection sequence)
- Rubber Diagnosis