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Glyphosate misuse in long-standing orchards

Glyphosate is a systemic non-selective herbicide of the glycine class, registered in India only for use in tea plantations. Its widespread off-label use in orchards has driven the Government of India to restrict its sale and use to certified Pest Control Operators since 2022.

Composition / Active ingredient

  • Active ingredient: Glyphosate (N-(phosphonomethyl)glycine)
  • Formulations seen: 41% SL (Roundup, Glycel and generics)
  • Chemical class: Phosphonoglycine

Mode of action

Glyphosate inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), the penultimate enzyme of the shikimate pathway that produces aromatic amino acids in plants and many micro-organisms. Without EPSPS, the plant cannot synthesise phenylalanine, tyrosine or tryptophan, and starvation kills it over 7-14 days. The enzyme is absent in animals, accounting for the molecule's low acute mammalian toxicity. HRAC Group 9.

The molecule is highly systemic in phloem and is translocated to all growing points — including roots, rhizomes and tubers — making it lethal to perennial weeds. The same systemic property is the source of orchard damage when spray drift or root uptake reaches a fruit tree's root zone.

Target use and regulatory status

The herbicide was originally CIBRC-registered for weed control only in tea plantations under the Insecticides Act 1968. Off-label use in citrus, mosambi (sweet lime), mango and other fruit orchards has been associated with progressive root decline and orchard collapse over 4-5 seasons of repeated under-canopy use.

By gazette notification published 25 October 2022, the Government of India restricted glyphosate use to certified Pest Control Operators (PCOs); CIBRC required all manufacturers to surrender their certificates of registration to incorporate prominent warning labels.

Alternatives in orchards

For under-canopy and bund weed control in fruit orchards, the safer alternatives are contact-only herbicides — Glufosinate Paraquat Bund Knockdown and Upl Sweep Power Glufosinate — applied with hood or foam directed spray to avoid root-zone exposure.

See also: Glufosinate Paraquat Bund Knockdown, Upl Sweep Power Glufosinate, Pendimethalin Cotton Preemergent.

References

  1. Indian government implements restrictions for glyphosate. Global Agriculture.
  2. Centre restricts glyphosate citing health hazards. Down to Earth (Oct 2022).