RUBBER NEWS

Establishing and Managing Rubber Budwood Gardens: Design, Care, and Grafting Standards in Vietnam

Posted on by content02.vinahugo
13
Oct

Budwood gardens play a vital role in Vietnam’s rubber industry, supplying high-quality scion wood for grafting and replanting programs. Proper site selection, soil management, and pruning practices ensure consistent bud quality and genetic purity across all rubber clones. This section outlines the Vietnam Rubber Group’s (VRG) technical standards for establishing and managing budwood gardens.

1. Site Selection and Garden Design

To achieve optimal growth and budwood quality, each garden must meet specific ecological and design criteria:

  • Site conditions: Choose areas with suitable climate, irrigation availability, light-textured soil, and good drainage. The site should allow easy access for transportation and management.

  • Design: Layouts must prevent erosion and waterlogging during rainy seasons and facilitate convenient management and harvesting.

  • Plot division: The garden should be divided into smaller plots measuring 50–100 m long and 20–30 m wide, separated by 3 m paths, and main roads 5 m wide.

  • Plant spacing and density:

    • Single rows at 1 m between rows and 0.5–1.0 m between trees.

    • Equivalent densities: 20,000 plants/ha (0.5 m spacing) or 10,000 plants/ha (1.0 m spacing), excluding roads.

  • Soil preparation:

    • Dig furrows 40 cm wide × 50 cm deep or plow equivalent trenches.

    • Apply 20 tons/ha of well-decomposed manure or other approved organic fertilizers, plus 1.1 tons/ha of fused phosphate, evenly mixed with the soil.

  • Planting materials:

    • Use bare-root stumps, top-cut stumps, or potted seedlings with leaf whorls.

    • Seeds may also be sown directly for in-garden grafting.

2. Garden Maintenance and Irrigation

Proper care and moisture management are essential to ensure vigorous scion growth and bark quality.

  • Watering:

    • Maintain soil moisture at planting, during fertilization, and before budwood harvest.

    • During dry seasons, irrigate 250 m³/ha per session, once per week for 6 weeks before cutting.

    • Under severe drought, increase to 2–3 times/week for 6 consecutive weeks.

  • Weed control: Maintain a weed-free environment using manual or chemical methods.

  • Shoot maintenance:

    • Year 2–3: Maintain 2 shoots per stump.

    • From Year 4 onward: Maintain up to 3 shoots, depending on rootstock size.

3. Variety Purification (Clonal Selection)

To ensure the purity of each clone:

  • Regularly remove wild shoots and ineffective branches.

  • Eliminate any mixed or off-type rootstocks.

Annual purification guarantees high genetic consistency and disease-free budwood.

4. Standards for Budwood (Scion) Quality

High-quality scion wood must meet the following standards:

  • Scions should be mature and easily peelable, matching the age of rootstocks.

  • Each meter of budwood should have at least 10 effective buds (for most clones).

  • Some clones, such as RRIV 106 or PB 255, may have fewer effective buds.

Only budwood that meets these standards can be used for grafting to ensure high success rates.

5. Leaf Layer Management and Budwood Cutting

Proper timing and cutting technique preserve bud vitality and bark integrity.

  • Leaf pruning (raising leaf tiers):

    • Conduct 20–25 days before budwood cutting.

    • Remove lower leaves, leaving 1–2 cm petioles, and keep the top two leaf whorls intact.

  • Budwood cutting:

    • Only cut branches with stable top leaves and easily peelable bark.

    • Perform cutting in cool weather.

    • Cut 10 cm above the shoot base, ensuring clean cuts.

    • Apply vaseline to seal the wound.

  • Expected yields of green-brown budwood per hectare:

    • Year 1: ~10,000 m

    • Year 2: ~22,000 m

    • From Year 3: ~30,000 m

6. Budwood Harvest Without Leaf Raising

When leaf raising is not applied:

  • Cut budwood with attached petioles (green buds).

  • Immediately trim leaves, leaving 1–2 cm petiole stubs, and store in cool, moist conditions.

  • During transport:

    • Stack budwood in layers with moist padding (e.g., sawdust or straw).

    • Do not tie tightly or expose to direct sunlight.

    • Spray light misting water during cool hours.

  • The time from cutting to grafting must not exceed two days.

7. Budwood Preservation and Transportation

  • After cutting, carefully collect and handle budwood to prevent bruising.

  • Seal both ends with wax or vaseline, store in a cool and humid place, never under sunlight.

  • For longer transport:

    • Wrap with wet jute sacks, moist sawdust, or damp straw (non-heating materials).

    • Tie into bundles of 20 branches, transport in vehicles with ventilated covers and moist padding layersbetween bundles.

    • Keep moisture by spraying water during cool hours.

  • The maximum time from cutting to grafting must not exceed five days.

8. Pruning and Regeneration

  • Shaping: Maintain a single main stem at 50 cm height. Subsequent cuts are made 10 cm above the previous harvest point.

  • Regeneration pruning: After 3–5 years of budwood harvest, cut the main stem below the initial shaping point to allow new shoot regeneration.

  • Re-grafting: Over-grafting to change clones is not recommended. If necessary, perform grafting only on new shoots after regeneration.

Conclusion

Establishing and maintaining budwood gardens under Vietnam Rubber Group standards ensures a sustainable supply of high-quality grafting materials. By following correct design, care, irrigation, pruning, and transport practices, producers can preserve genetic integrity and achieve optimal results in rubber seedling production.