Mode of action and rodenticidal chemistry
Zinc Phosphide operates as an acute inorganic toxicant targeting rodent metabolic systems.
- Chemical Reaction: Stomach hydrochloric acid reacts with ingested Zinc Phosphide to release toxic phosphine gas.
- Systemic Effect: Phosphine gas enters the bloodstream, damaging vital organs and blocking cellular oxygen respiration.
- Single-Dose Mortality: Rodents typically succumb within a few hours of consuming a lethal bait portion.
- Secondary Poisoning Risk: Poses lower secondary poisoning hazards to predators compared to chronic anticoagulants, though caution is required.
Field bait preparation and pre-baiting method
Rodents are naturally neophobic (suspicious of new food items), making pre-baiting essential for success.
- Pre-Baiting (Days 1 to 3): Place unpoisoned food grains (cracked wheat, millet, or rice with edible oil) in active burrows to build rodent confidence.
- Poison Baiting (Day 4): Mix Zinc Phosphide powder with fresh grain and edible oil strictly at CIBRC-approved label ratios (usually 2% active bait).
- Placement: Deposit bait spoons deep inside active burrow entrances or enclosed tamper-proof bait boxes.
- Bait Shyness: Never repeat Zinc Phosphide baiting within 60 to 90 days; surviving rats develop strong bait aversion.
Safety precautions and handling protocols
Extreme care is required to prevent accidental ingestion by children, pets, cattle, and farm birds.
- Always wear impermeable rubber gloves and a face mask while preparing and distributing poison baits.
- Never place poison powder openly on field bunds or around domestic cattle sheds.
- Collect and deeply bury all dead rodent carcasses and uneaten baits to safeguard scavenging birds and pets.
- Store concentrated powder in locked, dry cabinets away from water, acid, and food supplies.
Official source
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Central Insecticides Board & Registration Committee (CIBRC) ↗Related on KisanPe
Common questions
What is the active chemical in agricultural rat poison powder?
The primary active chemical used in agricultural rat poison powder in India is Zinc Phosphide, an acute inorganic rodenticide.
Why is pre-baiting necessary before using Zinc Phosphide?
Rats are suspicious of new foods; feeding them unpoisoned grains for two to three days ensures they consume a lethal dose when the poison bait is introduced.
What is bait shyness in rats?
If a rat consumes a sub-lethal dose of Zinc Phosphide and becomes sick, it associates the illness with the bait and refuses to eat it again for several months.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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