Pesticide Mixing and Spray
Biotechnology Advisor
About
1. General Guidelines for Safe Pesticide Mixing
The preparation of the spray suspension is a critical step that dictates both the biological efficacy of the chemical and the safety of the operator.
Standardized Dilution: In apple cultivation, pesticide recommendations are typically standardized based on a dilution factor, explicitly stated as the quantity of pesticide required per 100 liters of water, rather than per unit of land area
. Mixing Sequence: Always fill the spray tank to half its capacity with clean, neutral-pH water before adding the chemical. Pre-mix wettable powders (WP) or water-dispersible granules (WG) in a small bucket of water to form a uniform slurry before introducing them to the main tank.
Agitation: Ensure continuous mechanical or hydraulic agitation during mixing and application to prevent the precipitation of active ingredients or phase separation, particularly when using emulsifiable concentrates (EC) or Horticultural Mineral Oils (HMO)
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2. Orchard Spray Volume Requirements
The total volume of spray solution required for thorough canopy coverage varies significantly based on tree age, rootstock vigour, and planting density
Traditional Orchards (Seedling Rootstock)
Characterized by irregular spacing and large canopy volumes, accommodating approximately 20 plants per kanal
1–5 years: 3 L/plant resulting in 60 L/kanal
. 5–10 years: 5 L/plant resulting in 100 L/kanal
. 10–20 years: 8 L/plant resulting in 160 L/kanal
. >20 years: 15 L/plant resulting in 300 L/kanal
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Medium Density Orchards (MM-111 or MM-106 Rootstocks)
Standardized spacing (3 × 1.5 sq. m) accommodating approximately 111 plants per kanal
1–2 years: 1 L/plant resulting in 111 L/kanal
. 2–5 years: 2 L/plant resulting in 222 L/kanal
. >5 years: 4 L/plant resulting in 444 L/kanal
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High Density Orchards (M9 Rootstock)
Intensive planting architecture (3 × 1 sq. m) accommodating roughly 167 plants per kanal
1–2 years: 1 L/plant resulting in 167 L/kanal
. 2–5 years: 1.5 L/plant resulting in 250 L/kanal
. >5 years: 2.5 L/plant resulting in 418 L/kanal
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3. Equipment Configuration, Nozzles, and Calibration
Effective pest suppression, particularly for stationary pests like overwintering eggs or scale insects, relies on the physical delivery system.
Machinery Specifications: A standard setup for manual orchard spraying involves a 6.5 HP petrol-engine power sprayer equipped with a 200 ft spray pipe, spray gun, and appropriate nozzles
. Fuel Consumption: A 6.5 HP petrol engine consumes approximately 1.48 liters of fuel per hour of operation
. Nozzle Selection & Pressure: Use hollow-cone nozzles for standard fungicide and insecticide applications to generate a fine droplet mist that penetrates the dense apple canopy. Adjust the operating pressure to ensure uniform film deposition, which is especially critical for Petroleum Spray Oils (PSOs) as they act via physical suffocation and require complete coverage to runoff
. Labour Efficiency: A standard operating crew of two labour units can effectively apply 200 L of spray solution per hour
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4. Cost Economics and Field Capacity
Understanding the operational economics allows for optimized pest management budgets. Total costs are a combination of fixed machinery costs (depreciation, interest, taxes, insurance, housing) and variable operating costs (fuel, lubrication, repair, and labour)
Field Capacity: Orchards requiring less than 200 L of solution per kanal (Type-I) require roughly 1 hour of labor per kanal
. Conversely, mature or dense canopies requiring 200 to 450 L per kanal (Type-II) demand approximately 2.25 hours of active spraying per kanal . Application Expenses: The total application cost (excluding the chemical itself) for a Type-II orchard ranges from approximately Rs. 1040 to Rs. 1159 per kanal depending on the depreciation calculation methodology utilized
. Chemical Cost Variability: The choice of insecticide drastically shifts the total cost. For instance, spraying older trees (>20 years) with Neem oil (1500 ppm) can escalate total costs beyond Rs. 2,500 per kanal
. While older organophosphates like Dimethoate present lower material costs per kanal , their use is discouraged due to proven resistance failures in green apple aphid populations .