This biological control plan adheres to the strategy of “Prevention First, Integrated Management,” utilizing natural enemies, microbial agents, and physical methods to reduce reliance on chemical pesticides.

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1. Biological Control of Major Diseases

The core approach for soil-borne and fungal diseases is “Microbe-vs-Microbe” (Bio-antagonism):

• Sclerotinia Stem Rot (Sclerotinia sclerotiorum):
  • Soil Treatment: Incorporate Coniothyrium minitans or Trichoderma spp. into the soil during deep plowing/sowing to accelerate sclerotial decay and reduce primary inoculum.
  • Foliar Application: Spray Bacillus licheniformis or Bacillus subtilis during the early to full bloom stages to block fungal infection.
• Clubroot (Plasmodiophora brassicae) & Damping-off:
  • Seed Coating: Treat seeds with Bacillus polymyxa or Bacillus subtilis to protect seedling roots from pathogen invasion.
  • Soil Conditioning: Apply lime in acidic, high-incidence areas to adjust pH levels, and supplement with bio-organic fertilizers to improve the soil micro-ecosystem.

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2. Biological Control of Major Pests

Utilize natural predators and biological toxins for precision control:

• Rapeseed Aphids:
  • Biopesticides: Apply Metarhizium anisopliae  (a high-activity entomopathogenic fungus) when aphid populations reach the economic threshold.
  • Natural Enemy Conservation: Protect native ladybugs (Coccinella septempunctata), lacewings, and aphid parasitoid wasps. Release Harmonia axyridis (500-1,000 per mu) or parasitoid wasps (10,000 per mu) during the early infestation stage.
• Diamondback Moth & Cabbage White Butterfly:
  • Microbial Insecticides: Apply Bacillus thuringiensis (Bt) or Nuclear Polyhedrosis Virus (NPV) before larvae reach the 3rd instar.
  • Mass Trapping: Use frequency-vibration insecticidal lamps or yellow sticky traps to capture adults and reduce egg-laying.
• Flea Beetles & Leaf Miners:
  • Utilize botanical pesticides such as Rotenone for targeted foliar spraying.

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3. Integrated Pest Management (IPM) Techniques

• Physical Trapping: Install 20-30 yellow sticky cards per mu to monitor and trap aphids and leaf miners, positioned slightly above the crop canopy.
• Ecological Disruption: Implement paddy-upland rotation (e.g., Rice-Rapeseed rotation) to significantly lower the survival rate of clubroot and sclerotinia pathogens in the soil.
• Silver-Grey Mulching: Use silver-grey plastic film during the seedling stage to repel aphids through light reflection.

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4. Key Implementation Schedule

Stage	Core Method	Target
Sowing	Seed Coating (Bacillus) + Soil Treatment (C. minitans)	Clubroot, Sclerotinia, Seedling Pests
Seedling	Yellow Traps + Parasitoid Wasp Release	Aphids, Flea Beetles
Flowering	Biofungicide Spraying (B. subtilis)	Sclerotinia (preventing petal-borne infection)

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