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Mixture of capric and pelargonic acids (fatty acids)

A mixture of capric and pelargonic acids can be used to control weeds along buildings
Photo: Jardin botanique de Montréal (Édith Smeesters)
Taraxacum officinale

The information below is intended only as a guide. Always read product labels carefully.

Product description

Capric and pelargonic acids are saturated fatty acids from animal or vegetable sources.

Pesticides with a mixture of capric and pelargonic acids as the active ingredient are used to control weeds along buildings, fences and sidewalks, on driveways and between paving stones. They can also be used to eliminate weeds before planting or seeding.

These herbicides are available ready to use or as liquid concentrates to be diluted before use.

Target plants

Herbicides with a mixture of capric and pelargonic acids as the active ingredient may be used to control many different weeds, including:

  • common chickweed (Stellaria media)
  • common plantain (Plantago major)
  • lamb's-quarters (Chenopodium album)
  • redroot pigweed (Amaranthus retroflexus)
  • wild mustard (Sinapis arvensis)

NB: The product label lists the plants on which the pesticide may be used, along with the target organisms. 

How it works

The herbicide acts on contact. The fatty acids damage the waxy coating on plant leaves that protects them from desiccation. Treated plants usually dry out within 24 to 48 hours of application.


For best results, it should be applied in the spring or summer to young, actively growing weeds (ideally when they are less than 13 cm tall). Spray weeds thoroughly until foliage is wet, without run-off

Do not use when it is about to rain, or it may be washed off. If applied on a cool or cold day, the effects of the treatment will be delayed.

Repeat herbicide applications may be necessary to kill perennial or large weeds.

Wait 3 days after applying the herbicide before planting or seeding.


The product may irritate the skin and eyes, so it is best to wear gloves, long sleeves and pants and goggles when applying it.

The herbicide should be applied only to undesirable plants, as it can damage lawns. It is best to apply it on calm days, to keep it from drifting.

Do not use near any body of water or wetland, or dump any pesticide or rinse your equipment there, as this will contaminate the water. Never dump pesticides down sewers.

The pesticide may leave white residue on some brick or concrete surfaces. These deposits will disappear within a few weeks.

Keep out of reach of children.

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