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Classification of Herbicides
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Classification of Herbicides • Herbicide: It is a chemical used to kill some targeted plants. • Principles of chemical weed control • The selectivity exhibited by certain chemicals to cultivated crops in controlling its associated weeds without affecting the crops forms basis for the chemical weed control. Such selectivity may be due to differences in the morphology, differential absorption, differential translocation, differential deactivation etc. • Classification of Herbicides • 1) Based on Method of application • i) Soil applied herbicides: Herbicide act through root and other underground parts of weeds. Eg. Fluchloralin • ii) Foliage applied herbicides: Herbicide primarily active on the plant foliage Eg. Glyphosate, Paraquat • 2) Based on Mode of action • i) Selective herbicide: A herbicide is considered as selective when in a mixed growth of plant species, it kills some species without injuring the others. Eg. Atrazine • ii) Non-selective herbicide: It destroys majority of treated vegetation Eg. Paraquat • 3) Based on mobility • i) Contact herbicide: A contact herbicide kills those plant parts with which it comes indirect contact Eg. Paraquat • ii) Translocated herbicide: Herbicide which tends to move from treated part to untreated areas through xylem / phloem depending on the nature of its molecule. Eg. Glyphosate • 4) Based on Time of application • i) Pre - plant application (PPI) • Application of herbicides before the crop is planted or sown. Soil application as well as foliar application is done here. • ii) Pre – emergence • Application of herbicides before a crop or weed has emerged • For example soil application by spraying of atrazine on 3rd DAT to sugarcane can be termed as pre-emergence to cane crop while soil application by spraying the same immediately after a rain to control a new flush of weeds in a inter-cultivated orchard can be specified as pre-emergence to weed. Eg. Atrazine, Pendimethalin, Butachlor, Thiobencarb, Pretilachlor • iii) Post – emergence • Herbicide application after the emergence of crop or weed is referred as postemergence application. • When the weeds grow before the crop plants have emerged through the soil and are killed with a herbicide then it is called as early postemergence. • For example spraying 2,4-D Na salt to control parasitic weed striga in sugarcane is called as post-emergence while spraying of paraquat to control emerged weeds after 10-15 days after planting potato can be called as early postemergence. Eg. Glyphosate, Paraquat, 2,4-D Na Salt. • iv) Early post emergence: • Another application of herbicide in the slow growing crops like potato, sugarcane, 2-3 week after sowing is classified as early post emergence. • 5) Based on molecular structure • a. Inorganic compounds • b. Organic compounds • Thanks for Watching • • Subscribe for More videos • • Our Website, https://advanceagriclasses.com/ • • like on FB: / advance-agricultural-classes-209935129434632 • • join our fb group: / 1600626926901456 • • Follow us on Instagram: • / advanceagriclasses.official
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