Before knowing how to use a weed killer, it is essential to know how it endeavours.
Weed killers, also known as weedicide, are the chemicals used for killing unwanted plants growing in crop plants. They are classified based on site of action, Mode of action (MOD), toxicity, chemical characterization etc.
Classification of Weed Killers:
Based on the Method of application:
Based on the Method of application, weed killers are further classified into two categories.
- Soil applied weed killers: These types of weed fillers act through roots and underground parts of weeds. e.g. Fluchloralin
- Foliage applied weed killers: These type of weed killers primarily acts on the plant foliage. e.g. Paraquat
Based on Mode of action:
Based on Mode of application, weed killers are further classified into two categories.
- Selective weed killers: This type of weed killers are used when there is a mixed growth of plant species. They kill specific species without damaging other plants. e.g. Atrazine
- Non-selective weed killers: These types of weed killers indeed destroy most of the treated vegetation. e.g. Paraquat
Based on mobility:
Based upon the mobility weed killers are further classified into two categories.
- Contact weed killers: This type of weed killer kills the plant parts which comes in direct contact with the, e.g. Paraquat [REVISION]
- ranslocated weed killer/Systemic weed killer: They also act on untreated parts of the plant through xylem or phloem tissue depending on the nature of the molecule. e.g. Glyphosate
Based on Time of application:
Based on the Time of application, weed killers are further classified into four categories.
- Pre-planting application: This type of weed killers are applied before the plantation of crops. They are applied to soil as well as the foliar application is done. e.g. Fluchloralin is applied to the soil and also assimilated while sowing groundnut while Glyphosate is only applied to the foliage of perennial weeds before planting the crop.
- Pre-emergence application: They are applied before plantation of the crop or before the weed is emerged. For annual crops, this weed killer is applied after sowing the crop, and before the weed has emerged while in perennial crops, it is applied only before the weed is emerged. e.g. Atrazine, Pendimethalin, Butachlor, Thiobencarb.
- Post-emergence application: These types of weed killers are applied after the plantation of crops and after the emergence of the weed. Paraquat is applied to control