Chlorpyrifos 20% EC: Complete Guide to Uses, Dosage & Application (2026)
Fun fact: "Chlorpyrifos" and "Chlorpyriphos" are both spellings you'll see on Indian product labels. They're the same molecule. The industry hasn't made up its mind on the spelling, but it has absolutely made up its mind on the effectiveness — Chlorpyrifos 20% EC is the single most widely used insecticide in India, applied across more crop-hectares than any other insecticide in the country.
It's been in continuous use since 1965. If you're farming in India, you've probably used it. This guide covers how to use it correctly — the right timing, right dose, and how to get maximum results while managing resistance.
What is Chlorpyrifos 20% EC?
Chlorpyrifos 20% EC is a broad-spectrum organophosphate insecticide with triple action: contact, stomach, and vapour activity. The "20% EC" refers to 20% active ingredient in an Emulsifiable Concentrate formulation.
The vapour activity is the feature that distinguishes it from most other insecticides — it can kill insects that never directly contact the spray, just by being present near treated surfaces. This makes it particularly effective for soil-dwelling pests and insects sheltering inside crop canopies.
It is registered and approved for agricultural use in India by the Central Insecticides Board and Registration Committee (CIBRC). It is one of the foundational inputs in Indian crop protection and forms part of IPM (Integrated Pest Management) programmes across major crop systems.
How Does Chlorpyrifos Work?
Chlorpyrifos is an organophosphate that works by inhibiting acetylcholinesterase — a critical enzyme in the insect nervous system. When this enzyme is blocked, acetylcholine accumulates at nerve junctions, causing continuous nerve firing. The insect experiences paralysis, convulsions, and death.
The three modes of action:
- Contact: Kills insects that directly touch the sprayed surface
- Stomach: Kills insects that ingest treated plant material
- Vapour: The chemical vapourises slowly from treated surfaces, killing insects in enclosed spaces (soil, leaf rolls, plant crowns) that never contact the spray directly
The vapour action is particularly valuable for controlling termites, white grubs, and stem borers that feed below the soil surface or inside plant stems.
Pests Chlorpyrifos 20% EC Controls
| Pest Category | Specific Pests | Primary Crops |
|---|---|---|
| Soil pests | Termites, white grubs, cutworms, root borers | Sugarcane, cotton, groundnut, vegetables |
| Sucking pests | Aphids, jassids, whiteflies, thrips, mealybugs, leafhoppers | Cotton, chilli, vegetables, citrus |
| Stem & shoot borers | Yellow stem borer, shoot borer | Paddy, sugarcane, maize |
| Leaf folders / rollers | Paddy leaf folder | Paddy (rice) |
| Bollworms | American bollworm, pink bollworm | Cotton |
| Fruit borers | Brinjal fruit borer, tomato fruit borer | Brinjal, tomato, chilli |
| Scale insects / mealybugs | Citrus mealybug, mango scale | Citrus, mango, grapes |
| Grasshoppers / locusts | Various species | Multiple field crops |
Crops Where Chlorpyrifos 20% EC Is Used
- Cereals: Paddy (rice), wheat, maize, sorghum
- Cash crops: Cotton, sugarcane, tobacco
- Vegetables: Tomato, chilli, brinjal, okra, potato, onion, cabbage, cauliflower
- Fruits: Mango, citrus, grapes, banana, pomegranate
- Oilseeds: Groundnut, soybean, sunflower, mustard
- Pulses: Pigeon pea, chickpea, lentil
Chlorpyrifos 20% EC Dosage Chart
| Crop | Pest | Dose (per acre) | Method |
|---|---|---|---|
| Paddy | Stem borer, leaf folder, BPH | 400–500 mL in 150–200 L water | Foliar spray |
| Cotton | Aphids, jassids, whiteflies, bollworms | 400–500 mL in 200 L water | Foliar spray |
| Sugarcane | Termites, white grubs, borers | 1–1.5 L in 500 L water | Soil drench / basal spray |
| Tomato / Chilli | Aphids, mites, fruit borer | 300–400 mL in 200 L water | Foliar spray |
| Groundnut | White grubs, sucking pests | 1 L per hectare | Soil treatment / foliar |
| Maize | Stem borer, fall armyworm | 400–500 mL in 200 L water | Foliar spray |
| Citrus / Mango | Mealybug, scale insects | 3–4 mL/L water | Foliar spray to run-off |
| Termite control (soil) | Termites | 2–4 L per 100 L water | Soil treatment / trenching |
How to Apply Chlorpyrifos 20% EC
- For foliar sprays: use 150–200 litres of water per acre. Chlorpyrifos needs adequate coverage to be effective against contact-feeding pests. Under-diluted sprays miss insects on leaf undersides and in plant crevices.
- For soil pests (termites, white grubs): drench the soil around the plant base. The vapour action then works slowly through the soil column, reaching pests that foliar sprays cannot.
- Spray in early morning or evening. UV light degrades Chlorpyrifos; morning/evening application extends residual activity. At midday temperatures above 35°C, spray drift and evaporation reduce effective deposition.
- Rainfastness: allow 4–6 hours before rain. Chlorpyrifos needs time to bind to the leaf surface. If rain is forecast within 4 hours, delay the application.
- Use clean water. Hard water or highly alkaline water can hydrolyse the active ingredient, reducing efficacy. If your irrigation water is highly alkaline, lower the pH with a mild acidifier.
- Wear PPE. Organophosphates can be absorbed through the skin. Use gloves, protective clothing, and a face shield during mixing and application.
Resistance Management: Critical for Long-Term Effectiveness
Chlorpyrifos resistance has been documented in certain populations of cotton whitefly, Helicoverpa bollworm, and diamondback moth in India — a consequence of decades of over-reliance on organophosphates.
To preserve Chlorpyrifos effectiveness on your farm:
- Rotate with insecticides from different chemical groups: neonicotinoids (imidacloprid, thiamethoxam), avermectins (emamectin benzoate), diamides (chlorantraniliprole), or pyrethroids.
- Maximum 2 consecutive sprays of Chlorpyrifos per season on the same pest.
- Avoid sub-lethal doses. Diluting below recommended rates does not save money — it selects for resistant individuals in the pest population.
- Monitor pest populations. If a full-rate spray leaves significant live insects 72 hours later, resistance may be developing. Switch chemical groups immediately.
Chlorpyrifos 20% EC Price in India (2026)
- 500 mL: ₹180–₹260
- 1 litre: ₹320–₹420
- 5 litres: ₹1,400–₹1,800
At ₹350–₹420 per litre, a standard paddy/cotton spray (400–500 mL per acre) costs ₹140–₹210 per acre — making Chlorpyrifos one of the most affordable broad-spectrum insecticides available in India.
Buy Chlorpyrifos 20% EC on Farmkart with cash on delivery and fast delivery across India.
Frequently Asked Questions
Q: What is the difference between Chlorpyrifos and Chlorpyriphos?
A: They are the same molecule — two different transliterations of the same chemical name appear on Indian product labels. Both spellings are correct and refer to identical products.
Q: Can I mix Chlorpyrifos with fungicides?
A: Generally compatible with most fungicides including Mancozeb, Copper Oxychloride, and Propiconazole. Avoid mixing with alkaline formulations. Do a jar test before bulk preparation.
Q: Is Chlorpyrifos banned in India?
A: No — Chlorpyrifos is approved for agricultural use in India and is registered with CIBRC. It is banned or restricted in some other countries (EU, USA for certain uses) but remains a legal and widely used crop protection input in India.
Q: How long does Chlorpyrifos remain active in the soil?
A: Residual soil activity is typically 2–4 weeks depending on soil type, temperature, and moisture. In dry sandy soils it breaks down faster; in moist clay soils it persists longer.
Q: What is the pre-harvest interval for vegetables?
A: Typically 15–21 days for most vegetable crops. Check your product label — this is an important food safety parameter. Do not harvest before the stated PHI.
Q: Is Chlorpyrifos effective against whiteflies in cotton?
A: Historically yes, but resistance in cotton whitefly populations has been reported in some parts of India. If you observe reduced efficacy, rotate to a neonicotinoid (imidacloprid, thiamethoxam) or a newer-class insecticide.
