📈 Pest and Disease Management in Protected Cultivation

This lesson builds core elective concepts in BSc Agriculture with practical applications and exam-oriented clarity.

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Pest and Disease Management in Protected Cultivation

Unique Pest Challenges Under Protection

While protected structures reduce exposure to many open-field pests, the warm and humid microclimate inside greenhouses creates favorable conditions for certain pest and disease complexes. Once established, populations can explode rapidly in the enclosed space.

Major Insect Pests

Pest	Crops Affected	Damage Symptoms
Whitefly (Bemisia tabaci)	Tomato, capsicum, gerbera	Honeydew, sooty mold, transmits ToLCV and TYLCV
Thrips (Frankliniella occidentalis)	Capsicum, roses, gerbera	Silver streaking on leaves, petal browning, transmits TSWV
Spider mites (Tetranychus urticae)	Roses, carnation, cucumber	Yellow stippling, webbing on leaf undersides
Leaf miner (Liriomyza trifolii)	Tomato, chrysanthemum	Serpentine mines on leaves reducing photosynthesis
Aphids (Myzus persicae)	Most vegetables and flowers	Leaf curling, honeydew, virus transmission

Major Diseases

• Botrytis grey mold (Botrytis cinerea): Thrives in high humidity (above 85%) and cool temperatures. Attacks flowers, stems, and fruits. Prevention requires proper ventilation and humidity management below 75%.
• Powdery mildew (Leveillula taurica, Erysiphe spp.): White powdery patches on leaves. Common in capsicum and roses. Favored by moderate temperatures and dry leaf surfaces with humid air.
• Damping-off (Pythium, Rhizoctonia): Seedling disease in nurseries caused by overwatering and poor drainage. Use sterilized media and treated seeds.
• Fusarium wilt: Soil-borne fungus causing vascular browning and wilting. Managed through resistant rootstocks, media sterilization, and grafting.

Integrated Pest Management (IPM) Strategies

Physical and Cultural Methods

• Insect-proof nets (40 to 50 mesh) on all vents and openings
• Yellow and blue sticky traps for monitoring and mass trapping of whiteflies, thrips, and leaf miners
• UV-stabilized anti-virus nets that filter UV radiation and disorient insects
• Proper sanitation: Removal of crop residues, weed-free surroundings, and foot dip trays at entry points

Biological Control

• Encarsia formosa: Parasitic wasp for whitefly control
• Amblyseius swirskii: Predatory mite effective against whitefly and thrips
• Phytoseiulus persimilis: Predatory mite for spider mite management
• Trichoderma viride: Biocontrol agent applied to growing media against soil-borne pathogens
• Bacillus subtilis: Bacterial biocontrol agent for foliar and root diseases

Chemical Control

• Used as a last resort and with careful attention to pre-harvest intervals
• Prefer biopesticides like neem oil, spinosad, and Beauveria bassiana
• Rotate chemical groups to prevent resistance development
• Avoid broad-spectrum pesticides that harm beneficial organisms
• Always apply during cooler hours to prevent phytotoxicity in enclosed structures

Environmental Management for Disease Prevention

• Maintain relative humidity between 60 to 75% through ventilation and heating
• Avoid overhead irrigation; use drip or sub-irrigation systems
• Ensure adequate plant spacing for air circulation
• Remove and destroy infected plant material immediately

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Summary Cheat Sheet

Topic	Key takeaway
Main focus	Pest and Disease Management in Protected Cultivation.
Section context	Revise this lesson with the rest of Management & Economics for stronger conceptual continuity.