RUBBER NEWS

Pests and Diseases on Rubber Trees and Effective Control Methods

Posted on by content02.vinahugo
12
Oct

1. Principles of Pest and Disease Management in Rubber Trees

The first principle of pest management in rubber plantations is “prevention before treatment.”
Preventive care helps minimize costs and losses once an outbreak occurs—especially for seasonal fungal diseases like powdery mildew and Corynespora leaf fall.

Key management rules:

  • Carefully evaluate costs versus benefits before applying pesticides or fungicides.

  • Only use pesticides approved by the Ministry of Agriculture and Rural Development of Vietnam, and verified for use on rubber trees.

  • Always follow the four correct principles:

    1. The right chemical

    2. The right dosage/concentration

    3. The right time

    4. The right method

2. Classification of Rubber Tree Pests and Diseases

Rubber tree diseases are classified by the affected part of the plant, including:

  • Leaf diseases

  • Trunk and branch diseases

  • Tapping panel and bark diseases

  • Root and basal infections

3. Major Leaf Diseases on Rubber Trees

Leaf diseases cause the most direct impact on yield and tree growth, especially during the young stage and latex production phase.
Key diseases include:
Powdery mildew, Anthracnose (leaf blight), Rainy-season leaf fall, Corynespora leaf fall, Sunburn, Cold injury, and Chemical toxicity.

3.1. Powdery Mildew (Oidium heveae Steinm.)

  • Distribution: Common in all rubber-growing regions, especially during leaf shedding season.

  • Damage: Causes defoliation of young leaves and flowers across all ages.

  • Symptoms: White fungal spots on both leaf surfaces. Severely affected clones include VM515, PB235, PB255, RRIV4, GT1, etc.

Control:
Use fungicides containing hexaconazole (Hexin 5SC, Anvil 5SC, Saizole 5SC) at 0.2% or diniconazole (Sumi-Eight 12.5WP) at 0.05–0.1%.
Mix with adhesive BDNH 2000 at 0.2%.
Spray 400–700 L/ha, twice every 10 days, during cool hours (early morning or late afternoon).
Apply when 10–15% of trees have emerging young leaves.

3.2. Anthracnose (Colletotrichum gloeosporioides)

  • Occurrence: Predominantly in the rainy season.

  • Damage: Attacks young leaves and shoots in nurseries and young plantations, causing dieback.

  • Symptoms: Young leaves (<2 weeks old) fall prematurely; older leaves become deformed and leathery.

  • Severely affected clones: RRIM600, GT1, PB255, RRIV1–4.

Control:
Spray hexaconazole (Hexin 5SC, Anvil 5SC, Vivil 5SC) 0.2% + BDNH 2000 0.2%.
Apply every 7–10 days in early morning during rainy periods. Stop when 80% of trees have mature leaves.

3.3. Rainy-Season Leaf Fall (Phytophthora botryosa & P. palmivora)

  • Occurs: During continuous rainy periods.

  • Symptoms: Affected petioles show white resin-like nodules. Can spread to tapping panels causing stripe canker.

  • Susceptible clones: RRIM600, GT1.

Control:
Apply metalaxyl + mancozeb mixtures (Vimonyl 72BTN, Mexyl 72WP) at 0.2%.
Cut off infected shoots, treat with metalaxyl + mancozeb 2% and coat with vaseline.
Do not spray commercial tapping trees — instead, apply fungicidal paste directly on tapping panels.

3.4. Corynespora Leaf Fall (Corynespora cassiicola)

  • Seasonality: Year-round; peaks in May–June and August–September.

  • Damage: Causes multiple defoliations, stunted growth, yield loss, and even death in young trees.

  • Symptoms:

    • Circular gray-brown spots with yellow halos, sometimes forming holes.

    • Fishbone-like black lesions along veins (on sensitive clones).

    • Lesions on petioles/chutes may ooze sap and turn black, killing shoots.

Control:
Avoid sensitive clones (RRIC103, RRIM725, RRIV2–4).
Spray hexaconazole (Hexin 5SC, Saizole 5SC) 0.2–0.3% + BDNH 2000 0.2%.
Apply 2–3 times every 7–10 days when only 3–5% of leaves show symptoms.
Increase potassium fertilizer by 25% to boost disease resistance.
Stop latex tapping on severely infected trees.

4. Trunk and Branch Diseases

These diseases are difficult to control and directly affect latex yield and tree survival.

4.1. Pink Disease (Corticium salmonicolor)

  • Conditions: Common in low-altitude (<300 m) humid zones with distinct dry/rainy seasons.

  • Damage: Kills branches and shoot tips (ages 3–8 years).

  • Symptoms: White “spider-web” fungal growth turns pink as it matures; bark cracks with oozing latex.

Control:
Spray validamycine (Vivadamy 5SL, Validacin 5L) 1.0–1.2% or hexaconazole 0.5% + BDNH 2000 1.0%.
Repeat every 10–14 days until cured.
Stop tapping infected trees and prune/remove dead branches for burning.

4.2. Fusarium Bark Rot (Fusarium equiseti)

  • Occurrence: Common during rainy season on both young and mature trees.

  • Damage: Causes bark swelling, cracking, latex oozing, dieback, and yield loss.

  • Symptoms: Brown, spongy bark with blackened wood underneath.

Control:
Use hexaconazole 0.3%, metalaxyl 0.15%, or metalaxyl + mancozeb 0.3% + BDNH 0.3%.
Apply 2–3 sprays every 10–15 days.
For tapping trees, apply LSMC 99 or metalaxyl + mancozeb 2% paste on tapping panels.

4.3. Botryodiplodia Disease (Botryodiplodia theobromae)

  • Common in: Most rubber-growing regions, especially during rainy seasons.

  • Damage: Affects shoots, branches, and bark, leading to latex yield reduction (20–30%).

  • Symptoms:

    • Cracked lesions on young stems (1–2 years old) exuding latex.

    • In older trees, rough bark with dark pustules and peeling layers.

    • Prolonged infection can cause tapping surface death.

Control:
Spray hexaconazole 0.3–0.5% + BDNH 0.5–1.0%, 2–3 times every 2–3 weeks.
Cut dead shoots 10–20 cm below infection and seal cuts with vaseline.
Stop tapping heavily infected trees.

4.4. Stripe Canker on Tapping Panels (Phytophthora palmivora & P. botryosa)

  • Condition: Common in humid, cool environments.

  • Damage: Destroys tapping surfaces, sometimes causing complete latex loss.

  • Symptoms: Brownish vertical streaks above the tapping line, later merging into large rotting areas with foul-smelling yellow exudate.
    The inner bark decays, leaving black stripes on exposed wood.

Control:
Apply metalaxyl + mancozeb paste (2%) or LSMC 99 directly to affected panels.
Avoid tapping during infection.
Remove severely damaged bark to expose clean wood before applying treatment.

5. Conclusion

Rubber trees are high-value long-term crops, but they face threats from multiple fungal and physiological diseases.
To ensure sustainable yields:

  • Prioritize preventive management.

  • Use approved, effective fungicides with proper dosage and timing.

  • Strengthen trees’ natural resistance through balanced fertilization and sanitation.

  • Always monitor weather changes (especially transitions from wet to dry seasons).