Farmers’ Guide With Joseph Mugenyi: Herbicides Application In Farming

Farmers’ Guide With Joseph Mugenyi: Herbicides Application In Farming

By Joseph Mugenyi

Kampala: Herbicides are agricultural chemicals used to control weeds.

These reduce on Labour expense and time.

Herbicides are classified according to;

  • Use
  • Mode of action
  • Time of application
  1. Herbicide classification according to use;

Examples include,

Selective herbicides;-

 These kill or impair the growth of a certain plant species when applied to a mixed plant population but cause no injury to the wanted plant.

These include 2.4 Amine (kills weeds in millet plants, metrazin in maize) etc.

Each crop has a specific herbicide used in weed control so always be careful during application because when applied on a wrong plant it instead kills even the wanted plant.

Non selective;-

They will kill every plant they come in contact with.

They contain an active ingredient called glyphosate e.g. round-up, weed master, weed solution, pinup etc.

Land Sprayed by Non Selective Herbicides
  • Classification of herbicide based on mode of action.

Contact herbicides;-

These kill plant tissues that come in direct contact with them.

All are applied to the foliage/leaves of the plant. E.g. paraquat

Translocated / systemic herbicides;-

These are readily absorbed by the leaves, stem or roots then move through the vascular system of the plant to organs where they exert their toxic actions. E.g. weedmaster.

  • Soil sterilants

These prevent the growth of all plants while present in the soil.

Their effect may be temporary or may last longer depending on the type.

E.g. bromacid-4yrs


Atrazine -1yr, (this is not usually recommended.)

 3. Classification of herbicides according to time of application.

Pre-planting herbicides;-

These are herbicides applied before planting.

They may affect the germination process.

They easily kill weeds. E.g. glyphosate.

Post emergency herbicides:-

These are applied after planting e.g. 2.4d amine.

They are both systemic and contact

They are usually applied on foliage/leaves.


Usually spray in either morning or evening hours for easy penetration of the herbicides.

Use recommended quantity of herbicides.

Herbicides are both in liquid and granular form.

There are both organic and inorganic herbicides on market.

They are very poisonous, so be extra carefull during application and storage.

Don’t mix different herbicides together.

You may not like the results.

Get all the agricultural information here bi-weekly.Mugenyi Joseph (MJ Farmer) is a practicing Agribusiness entrepreneur based in Kibiito and a software Engineering student at Makerere University. He can be reached on 0701-443309, an accessible web community

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