> ## Documentation Index
> Fetch the complete documentation index at: https://badixth-dc85e378.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Diagnose and Respond to Ganoderma Basal Stem Rot in Oil Palm

> Identify Ganoderma basal stem rot from shelf-shaped brackets at the trunk base, one-sided frond collapse, and clustered mortality, and manage it with regular census, sanitation, resistant planting material, and disciplined replanting.

Ganoderma basal stem rot (BSR), caused primarily by *Ganoderma boninense*, is the most economically damaging disease of oil palm in Southeast Asia and is increasingly reported in West Africa. It rots the trunk from the base upward, kills palms after 8 to 15 years, and expands as clusters within a block. There is no effective in-field cure once a palm is heavily infected; management is a *program*, not a single spray.

**Regional priority:** Very high in Malaysia, Indonesia, Papua New Guinea, and increasingly Colombia and Nigeria. Any oil palm block over 8 years old should be under a Ganoderma monitoring program.

## When oil palm is most vulnerable

Susceptibility increases with age. First-generation plantings on former forest land show infection from 8 to 12 years. Second-generation and later replantings on former oil palm land often show infection much earlier (from 4 to 6 years) because the pathogen persists on old stumps and roots.

## How Ganoderma shows in satellite data

* **Individual-palm decline** in very-high-resolution or drone imagery: one crown yellowing, then collapsing, while neighbors remain healthy.
* **Cluster expansion** month over month - Ganoderma spreads through root contact, so infected palms tend to appear near previously infected ones.
* **Block-scale NDVI or EVI decline** on older stands with chronic Ganoderma pressure - a slow, multi-year trend rather than a seasonal drop.
* Regular high-resolution imagery is the best remote signal; standard Sentinel-scale imagery misses individual palms until damage is widespread.

<Warning>
  Trunk brackets are a late sign. By the time brackets are visible, 50% or more of the internal trunk tissue is already rotted. Trunk-tapping and quarterly census catch it earlier than imagery alone.
</Warning>

## Field symptoms

* **Basal brackets** - shelf-shaped, kidney-shaped, or hoof-shaped fruiting bodies at or near ground level. Young brackets are white or cream; mature brackets are reddish-brown on top with a white rim.
* **One-sided frond collapse** - fronds on one side of the crown snap and hang; the other side may still look healthy for months.
* **Unopened spear standing upright** while surrounding fronds are dying - the classic "flag-leaf" appearance of a late-stage palm.
* **Multiple hanging dead fronds** ("skirt") persist around the trunk.
* **Hollow-sounding trunk** when tapped with a machete handle - detectable months before external brackets appear.
* **Reduced bunch load** on affected palms for 6 to 12 months before visible collapse.
* **Clustered mortality** - dead palms grouped rather than randomly scattered.

## Reduce the damage by

Ganoderma control is a *program*, not a single intervention. Combine the following:

* **Regular census** - inspect every palm on every block over 8 years old at least quarterly. Record and geo-tag every infected palm.
* **Sanitation felling** - fell heavily infected palms and remove or destroy the base and stump. Do not leave infected material on site.
* **Windrow management at replanting** - chip and spread residues; do not pile stumps. The classic "clean planting" reduces inoculum carryover to the next generation.
* **Mounding at planting** - plant on raised mounds where feasible; reduces basal water contact and delays infection.
* **Plant Ganoderma-tolerant material** where available - several breeding programs (MPOB, Sime Darby, IOI, and others) now release partially resistant progeny.
* **Trichoderma and other biological amendments** - shown in field trials to slow onset; use as part of a program rather than a stand-alone control.
* **Do not interplant with young palms among heavily infected old palms** - infection transfers through root contact.
* **Avoid physical trunk wounding** during harvesting - wounds are entry points.

<Note>
  Chemical fungicides applied to soil or trunk have shown limited durable effect on Ganoderma. Do not rely on chemistry as the primary control.
</Note>

## Set an alert for early warning

<Tip>
  Turn the diagnosis into a trigger. Ganoderma is a *census discipline* backed by satellite - the alert prompts the walk, and the walk confirms the palm.
</Tip>

Recommended settings for Ganoderma on oil palm:

* **Quarterly census reminder** - schedule via calendar, not just imagery. Every palm on stands over 8 years, at least four times per year.
* **Palm-cluster NDVI drop alert** - trigger when a localized zone (a cluster of 3 to 5 palms) drops NDVI 0.10 or more month over month while the block average remains stable.
* **High-resolution imagery review** - schedule a drone or very-high-resolution pass at least twice per year on high-pressure blocks.
* **Cumulative census dashboard** - review Ganoderma count per block per year; a rising slope on second-generation replanting is a warning to escalate sanitation.

## Related

* [Oil Palm Diagnosis](/guides/Crop/Oil-Palm/oil-palm-diagnosis)
* [Field Walk Protocol](/guides/Crop/Oil-Palm/field-walk-protocol) - the trunk-tapping and census sequence.
* [Upper Stem Rot](/guides/Crop/Oil-Palm/biotic/diseases/upper-stem-rot) - Ganoderma variant on the mid-trunk.
* [Set up automated crop alerts](/guides/alerts-notifications)