Practical Implementation of Push & Pull Strategies
in NFT and DFT Systems
This article is the second part of a series on integrated pest management in hydroponic systems.
1. Target Pests and Species-Specific Strategies
| Pest Group | Common Species | Recommended Push Substances | Effective Pull Methods | Specifics in Hydroponics |
|---|---|---|---|---|
| Aphids (Aphidoidea) |
Green Peach Aphid (Myzus persicae) |
Azadirachtin, Pyrethrins, Rosemary Extract |
Yellow Sticky Traps, Mustard Plants, Aphis Pheromones |
Rapid Reproduction, Systemic Virus Transmission |
| Whiteflies (Aleyrodidae) |
Greenhouse Whitefly (Trialeurodes vaporariorum) |
Neem Oil, Citrus Extracts, Diatomaceous Earth |
Yellow Sticky Traps, Nasturtium, Optical Traps |
Frequent Development of Insecticide Resistance |
| Spider Mites (Tetranychidae) |
Two-Spotted Spider Mite (Tetranychus urticae) |
Canola Oil Formulations, Plant Strengtheners |
Phytoseiulus Mites, Color Traps (blue) |
Prefer Dry Conditions, High Reproduction Rate |
| Thrips (Thysanoptera) |
Western Flower Thrips (Frankliniella occidentalis) |
Spinosad, Neem Extracts, Essential Oils |
Blue Sticky Traps, Amblyseius Mites, Pheromone Traps |
Hidden Lifestyle, Difficult Control |
| Leafminers (Agromyzidae) |
Tomato Leafminer (Liriomyza bryoniae) |
Azadirachtin, Abamectin Formulations |
Yellow Sticky Traps, Parasitoid Wasps |
Larvae Protected within Leaf Tissue |
2. Push Substances: Active Ingredients and Application
Botanical Insecticides
Azadirachtin (Neem)
- Mode of Action: Antifeedant, Molting Disruption
- Concentration: 0.01-0.05% in Nutrient Solution
- Compatibility: Selective, Beneficial-Friendly
Pyrethrins
- Mode of Action: Neurotoxic, Contact Poison
- Application: Foliar Spray (0.1-0.2%)
- Note: Photolabile, Apply in the Evening
Microbial Agents
Spinosad
- Origin: Saccharopolyspora spinosa
- Target Spectrum: Thrips, Caterpillars, Beetles
- Application: Systemic via Nutrient Solution
Bacillus thuringiensis
- Target Spectrum: Larval Stages (Lepidoptera)
- Application: Foliar Treatment upon Infestation
- Specificity: Species-Specific Strains
Plant Strengtheners
Diatomaceous Earth
- Mode of Action: Physical, Desiccation
- Application: Leaf Powder at Low Humidity
Essential Oils
- Examples: Rosemary, Thyme, Mint
- Effect: Repellent, Antimicrobial
- Formulation: Emulsified Sprays
Application Note: Compatibility with hydroponic systems must be checked prior to use. Not all formulations are suitable for recirculating systems (Resh, 2013).
3. Pull Methods: Attractants and Trap Systems
Visual Attractions
Color Traps
- Yellow Traps: Whiteflies, Aphids, Leafminers
- Blue Traps: Thrips, Fungus Gnats
- Optimal Placement: 10-20 cm above plants
Reflective Mulches
UV-reflective mulch films confuse flying insects and reduce landing attempts on crop plants (Antignus, 2000).
Chemical Attractions
Pheromone Traps
- Sex Pheromones: Species-specific attraction
- Aggregation Pheromones: Attraction of both sexes
- Dispenser Systems: Long-lasting effect (4-8 weeks)
Plant-Based Kairomones
Scent compounds that mimic natural host plants, attracting pests specifically (Khan et al., 2008).
Trap Crops - Specific Combinations
| Main Crop | Target Pest | Trap Crop | Placement | Efficacy |
|---|---|---|---|---|
| Tomato | Whitefly | Nasturtium, Tobacco | Perimeter, 5% of area | 75-85% Reduction |
| Cucumber | Spider Mites | Beans, Eggplant | Between rows | 60-70% Reduction |
| Bell Pepper | Aphids | Mustard, Canola | Corner positions | 80-90% Reduction |
| Lettuce | Leafminers | Celery, Parsley | Border areas | 70-80% Reduction |
4. System Implementation and Combination
NFT Systems: Specific Adaptations
Push Strategies
- Systemic Application: Low concentrations (0.01-0.05%)
- Timed Dosing: 4-6 hours per treatment
- Compatibility Test: Test on individual plants first
Pull Strategies
- Space Optimization: Vertical trap arrangement
- Trap Crops: In separate NFT channels
- Air Circulation: Optimize pheromone distribution
DFT Systems: Specifics
Utilizing Advantages
- Larger Buffer Volume: More stable active ingredient concentrations
- Longer Residence Time: Lower dosages possible
- Filter Integration: Activated carbon for residue removal
Challenges
- Active Ingredient Degradation: Consider microbial degradation
- System Cleaning: Necessary after treatment
- Cost: Higher active ingredient requirement
5. Monitoring and Adaptive Management
Integrated Monitoring System
Damage Indices
- Aphid Infestation Index (0-5 scale)
- Thrips Damage Score (Western Flower Thrips)
- Egg/Larva Count per Leaf
Chemical Monitoring
- Active Ingredient Concentration in Nutrient Solution
- Pheromone Release Rates
- Residue Analysis
Plant Physiology
- Chlorophyll Fluorescence (Fv/Fm)
- Leaf Temperature Differential
- Growth Rates
References
- Resh, H. M. (2013). Hydroponic Food Production: A Definitive Guidebook for the Advanced Home Gardener and the Commercial Hydroponic Grower. CRC Press.
- Antignus, Y. (2000). Manipulation of wavelength-dependent behaviour of insects: an IPM tool to impede insects and restrict epidemics of insect-borne viruses. Virus Research, 71(1-2), 213-220.
- Khan, Z. R., James, D. G., Midega, C. A., & Pickett, J. A. (2008). Chemical ecology and conservation biological control. Biological Control, 45(2), 210-224.
- Van Lenteren, J. C. (2012). The state of commercial augmentative biological control: plenty of natural enemies, but a frustrating lack of uptake. BioControl, 57(1), 1-20.
- Stenberg, J. A., et al. (2015). Optimizing crops for biocontrol of pests and disease. Trends in Plant Science, 20(11), 698-712.
Next Article in the Series: Semiochemicals in Hydroponics: From Research to Practice
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