Selective herbicides: Mechanism and examples
- Definition: Herbicides formulated to control specific weed species (such as broadleaf weeds, grasses, or sedges) without causing physiological injury to the companion crop.
- Crop tolerance mechanisms: The cultivated crop safely metabolizes, degrades, or compartmentalizes the chemical before it reaches toxic concentrations.
- Common selective examples: 2,4-D (controls broadleaf weeds in wheat, rice, and sugarcane); Atrazine (controls broadleaves and grasses in maize); and Imazethapyr (controls mixed weeds in soybean and pulses).
- Application: Applied as pre-emergence or post-emergence sprays directly over the standing crop at recommended growth stages.
Non-selective herbicides: Mechanism and examples
Non-selective herbicides destroy all green plant tissue upon contact or absorption, making no distinction between crops and weeds. Common examples include Glyphosate (systemic EPSPS inhibitor) and Glufosinate-ammonium (contact glutamine synthetase inhibitor). They are restricted to non-crop land, irrigation bunds, pre-sowing zero-tillage field burn-down, or directed inter-row hooded spraying.
Spray equipment, drift precautions and nozzles
- Always use flat-fan or flood-jet nozzles operating at low pressure to prevent drift-prone fine droplets.
- When applying non-selective herbicides near standing crops, use a protective plastic spray hood over the nozzle to prevent chemical contact with crop stems.
- Thoroughly clean and rinse spray tanks and delivery hoses before using the equipment for other agricultural applications.
Official source
Check the latest rules, benefits and forms here. KisanPe is an independent platform and is not a government website.
Directorate of Plant Protection, Quarantine & Storage (CIBRC) ↗Related on KisanPe
Common questions
What is the key difference between a selective and a non-selective herbicide?
A selective herbicide kills target weeds without harming the crop, while a non-selective herbicide kills all green vegetation it contacts.
Can non-selective herbicides like Glyphosate be sprayed directly over crops?
No. Non-selective herbicides will kill regular standing crops; they can only be used before sowing, on field bunds, or with protective spray hoods.
Where can farmers check approved herbicide recommendations?
On the official portal of the Directorate of Plant Protection, Quarantine & Storage (ppqs.gov.in) under CIBRC approved lists.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
More Crop Protection & Pesticides guides
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