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 the emerged weeds after planting a potato within 10-15 days. e.g. Glyphosate, Paraquat.
- Early post-emergence: These types of weed killers are applied to low-growing plants like sugarcane, potato etc. 2-3 weeks after sowing.
Guide on how to use Weed Killers:
Follow the instructions given on label: Check the purpose of weed killer. Go through the storage, disposal and use of weed killer. Don’t forget to Follow the cautions given and check the level of toxicity. Mix exact proportions according to the requirement: Weed killers will not work efficiently with higher concentration. The more massive dose may lead to negative consequences. Mix the required amount of weed killer. Make sure it is not stored only the amount that is needed. Dilute the chemical weed killer by 1-part chemical 100 parts water. This is a 1% mix, and this will be of less strength. For a more reliable mix, to kill weeds such as Scutch grass two %mix will be a better choice. Ten litres of weed killer mix is sufficient to kill a large number of weeds. Spraying from 10 cm above the height of the weeds will ensure proper coverage.
Choose suitable weather condition: Make sure to use the weed killers during suitable weather conditions. Avoid applying weed killers if there is a chance of raining in the next 24 hours. Make sure not to use weed killers in windy weather because they may damage the surrounding plants. Avoid using weed killers in windy weather because they may damage surrounding plants. Choose the best Time: It is better to use the weed killers in morning and evening times. Use separate equipment for weed killers so that it will not affect the plants. Granular weed killers are applied when the grass is Moist. Make sure not to water the plant for 48 hours after the application of weed killer. The dampness will help the weed killer to stick on the leaf. Watering the plant soon after applying weed killer can wash off the chemical before it gets absorbed.
For the excellent association of weed killer with the weed, make sure not to mow the grass. Mowing decreases the efficiency of the weed killer on the plant. Don’t cut the grass two days after the application of weed killer and five days before the application. Identify the area of weed before applying weed killer: Make sure the plants are not close while spraying the weed killer because it may affect the green plant which is in contact with the weed, for better results use a Ready-To-Use Spray which can be treated in small areas. Make sure to shake the bottle well before using the weed killer to disperse the contents. Do Not directly apply the weed killer to the cropland without diluting it. Let the weed die entirely before removing it from the land.
Do not let the water runoff onto the main plant because the weed killer will be carried from leaf to root system. Granular weed killers are more effective than liquid weed killers. Use liquid weed killers for vigorous weeds for better results. 65 and 85 F is considered the ideal temperature for applying post herbicides. Weeds are killed slowly below 60 F. Some weed killers damage the crops if applied above 85F. Make sure not to apply volatile weed killers in hot weather conditions. Make sure not to use a weed killer with a higher concentration of Glyphosate. Glyphosate quickly spreads throughout the plant and penetrates the root, eventually killing the main crop. Use a chemical resistant sprayer for easy and practical application of weed killer. It works well in reaching the hard spots.