Botryodiplodia disease (Botry) mainly affects the bark and stem of rubber trees and can occur throughout almost all growth stages. When infection reaches level 4 or higher, latex yield can drop by 20–30%. If left untreated, the disease may cause complete tapping panel dryness. Therefore, early identification and timely treatment are essential to protect plantation productivity.
Symptoms and Identification
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Botryodiplodia disease is caused by the fungus Botryodiplodia theobromae Pat., which attacks rubber trees during most growth stages and is common across Vietnam’s rubber-growing regions.
The fungus is most active during the rainy season, and aside from rubber, it can infect over 500 other woody plant species.
At high infection levels, the disease reduces grafting success rates, kills seedlings, slows growth, and lowers latex yield by up to 30%. Severe, long-term infections can result in complete bark necrosis and tree death.
Common Symptoms by Growth Stage
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Nursery and Budwood Gardens:
Small nodules appear on the rootstock, merging to form rough, scaly bark. The bark becomes resin-poor and difficult to peel, reducing graft success. Infection occurs around the graft union when bandages are removed, leading to graft failure or death. -
Seedling and Replanting Stage:
Dark, sunken lesions appear on shoots, later spreading upward and downward, leading to dieback. The bark darkens with black fruiting bodies containing spores. The infected wood turns white with fine dark streaks, and the dead bark adheres tightly to the wood. -
Budding Gardens:
Small nodules appear on young brown-green bark, merging and making bark peeling difficult during grafting. -
Immature Trees (1–2 years, green-brown bark):
Diamond-shaped cracks develop on shoots, with latex oozing and blackening. Bark and wood dry out and become spongy. Leaves above the infected zone wilt and dry but do not fall. The disease often appears during seasonal transitions, affecting clusters of 10–15 trees per site. -
Mature Trees (3+ years, brown bark) and Tapping Trees:
Small bumps (1–2 mm) appear, later merging into patches of 4–5 cm² or spreading along branches and trunks.
Severe infections cause bark thickening, cracking, and flaking. Latex flow declines, and tapping panels may dry out completely.
The fungus penetrates through cracks or tapping wounds, destroying cambium tissue and reducing both tree vigor and latex yield.
Prevention and Control Measures
Proper identification is key — avoid confusion with similar symptoms caused by physiological dryness, sunburn, lightning strikes, frost, or drought.
1. General Principles
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Apply fungicides only during the rainy season.
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For immature and mature trees, treat only when over 50% of trees show level 2 or higher infection.
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Trees with level 4 or above infection should be treated immediately and suspended from tapping until recovery.
2. Nursery and Budwood Gardens
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Preventive spraying on new grafts and young plants using:
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Hexaconazole (Hexin 5SC, Anvil 5SC, Vivil 5SC, Saizole 5SC) at 0.3%
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Tebuconazole (Vitebu 250SC) at 0.15%
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Pyraclostrobin (Headline 250EC) at 0.03%
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Add BDNH 2000 adhesive at 0.3% concentration.
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Spray 2–3 times at 10–15 day intervals.
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Ensure seedlings are disease-free before planting.
3. Immature Trees (1–2 years)
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Use:
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Hexaconazole 0.3–0.5%
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Tebuconazole 0.2%
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Pyraclostrobin 0.04%
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Combine with BDNH 2000 adhesive 0.5%
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Spray 2–3 times every 10–15 days using a backpack sprayer.
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When shoots die, cut 10–20 cm below the infection site at a 45° angle, then apply a thin layer of vaseline to seal the wound.
4. Mature and Tapping Trees
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Spray with Hexaconazole 0.5% plus BDNH 2000 adhesive 0.5–1.0%.
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Apply 2–3 sprays at 10–15 day intervals, ensuring full coverage of the infected bark (0–3 m height from the base).
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Stop tapping on severely infected trees until the disease is under control.
Conclusion
Botryodiplodia disease remains one of the most serious fungal threats to rubber plantations in Vietnam, significantly reducing latex yield and tree longevity.
Applying the proper preventive fungicide treatments, maintaining clean planting materials, and ensuring early detection and intervention are critical for sustaining healthy, productive rubber plantations.