Propagating Fusarium oxysporum for agarwood inoculation involves cultivating the fungus in a controlled environment to produce a viable and effective inoculant. Below is a step-by-step farmer-friendly protocol for propagation and preparation:
Fusarium oxysporum Propagation Protocol
For Agarwood Inoculation Use
1. Isolation and Pure Culture Maintenance
- Source: Obtain pure Fusarium oxysporum strain from a reputable laboratory or isolate from infected agarwood tissue.
- Medium: Use Potato Dextrose Agar (PDA) for culturing.
- Steps:
- Sterilize PDA in autoclave or pressure cooker.
- Pour into sterile Petri dishes and let solidify.
- Inoculate with a small plug of the fungus.
- Incubate at 25–28°C for 7–10 days.
2. Liquid Culture Expansion (for Field Use)
- Medium: Potato Dextrose Broth (PDB) or Sabouraud Dextrose Broth.
- Steps:
- Prepare broth in sterilized flasks or bottles (500 mL – 1 L).
- Inoculate with mycelial plugs from the solid culture.
- Incubate on a shaker or gently swirl twice daily.
- Grow for 7–10 days until dense fungal biomass appears.
3. Fermentation and Inoculant Preparation
- Strain Strengthening (Optional):
- Add 0.5% NaCl or 1 g MnO₂ during fermentation to adapt the fungus.
- Dilution for Field Use:
- Mix 100 mL of fungal broth with 900 mL of sterile water or 1% molasses water.
- Filter through mesh if needed.
- Shelf-life: Use within 7 days or refrigerate for up to 1 month.
4. Inoculation into Aquilaria Trees
- Age of Trees: Best for 3–5 years old.
- Method:
- Drill 1–1.5 cm holes at 30° angles into the trunk or large branches.
- Inject 10–15 mL of fungal suspension per hole.
- Seal with cotton or wax to prevent contamination.
Precautions:
- Work in a sterile environment to avoid contamination.
- Always label cultures with strain name, date, and medium.
- Use personal protective equipment (PPE) during handling.
- Avoid inhalation of spores.