Fusarium bark rot, caused by the fungus Fusarium equiseti, is a destructive disease that affects both young and mature rubber plantations in Vietnam. The fungus thrives in humid conditions during the rainy season, causing bark decay, cambium necrosis, and latex production losses.
1. Causal Agent and Distribution
Table of Contents
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Pathogen: Fusarium equiseti
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Distribution: Found in immature (KTCB) and mature (commercial) rubber plantations across Vietnam.
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Activity: The fungus develops most aggressively during the rainy season, spreading through airborne spores and moisture contact.
2. Damage and Impact
Fusarium bark rot affects nearly all tree parts, with severe impact on:
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Young plantations: slows vegetative growth, weakens the canopy, and may cause dieback.
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Mature trees: damages tapping panels, leading to latex yield reduction and long-term productivity loss.
If left untreated, the infection can cause complete bark necrosis, tapping face rot, and dieback of upper branches.
3. Symptoms
In immature plantations (1–2 years old):
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Bark and wood tissues swell, turn brown, and crack.
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Latex oozes from fissures; leaves may fall prematurely.
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Young shoots and branches dry back, and trees stop growing.
In commercial plantations:
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Disease appears on tapping panels and cuts as dark brown to black lesions.
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Rotten, spongy bark with brown discoloration spreads progressively.
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Beneath the lesion, a rubbery latex layer (cushion) forms, while inner wood darkens.
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Boundary lines (rahn tien, rahn hau) crack and darken inside the bark layer.
(See Figure IX.9)
4. Control and Treatment
a. Immature Plantations (KTCB)
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Spray fungicides:
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Hexaconazole 0.015% (150 ppm) or
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Metalaxyl 0.0525% (525 ppm).
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Add 0.3% adhesive to enhance penetration.
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Apply 2–3 times at 10–15 day intervals during the rainy season.
b. Mature Plantations (Commercial Trees)
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Suspend tapping on severely infected trees.
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Apply Metalaxyl 0.35% (3,500 ppm) mixed with 1.0% adhesive on the entire tapping panel.
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Treat 2–3 times every 10–15 days for all affected trees in the block.
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For adjacent plots, perform preventive coating once per month during the rainy season.
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Apply fungicide evenly across the tapping cut and 1–1.5 cm above the regeneration bark strip.
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Disinfect tapping knives using the same fungicidal solution to prevent cross-contamination.
5. Preventive Recommendations
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Maintain good drainage to prevent prolonged waterlogging.
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Avoid mechanical injury to the trunk and tapping area.
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Use sanitized tools and ensure workers follow proper hygiene protocols.
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Regularly inspect during rainy months to detect early infection signs.
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Combine with balanced fertilization to improve tree resistance.
6. Summary
Fusarium bark rot is among the most economically damaging fungal diseases in rubber plantations.
Timely detection, strict tool sanitation, and preventive fungicide application are key to controlling infection and sustaining latex productivity.