Herbicides are chemicals used to kill weeds (unwanted plants) that tend to compete with the grown crops. Herbicides can be selective or non-selective. Each of these groups can be sub-divided into three namely;
  • Contact
  • Systemic
  • Residual


These are weed killers which by their chemical composition are capable of acting bio-chemically on either broad-leaved weeds or grasses. They are used predominately in monocropping situations.
However, when these herbicides are used in high concentration, they tend to have phytoxic effect on cultivated crops. Selective herbicides that kill grasses only are Alachlor, Pendimenthalin etc. also those that kill broad leaves weeds only are Atrazine, Imasaquine etc.

Examples of selective commercial herbicide are:


  • Basamaize for maize.
  • Ronster for rice.
  • Galex for cowpea, soyabeans, groundnut.
  • Basegram for rice and maize.
  • Cotoran for cassava.
  • Primextra for maize, cassava and yam. 
  • Diuron for yam and cassava.


These are otherwise known as total weed killers. They are used for weed control in any weed combination in the field, they will kill any kind of vegetation. Example is Glyphosate (Round-up).



  • CONTACT HERBICIDES: These are types of herbicides kill any vegetation or weeds immediately after application. They stop all biological activities. E.g paraquat, gramoxone, basta etc.
  • SYSTEMIC HERBICIDES: These are slow action type whose effects are not noticed until few days or week after application. Their effect is a thorough but gradual killing of most stubborn and perennial weeds. They have the ability to move around the transportation and translocation systems to achieve a total kill e.g Glyphosate.
  • RESIDUAL HERBICIDES: These are soil acting weed killers whose effects on weed control are primarily as photosynthetic inhibitors. They can have both pre and post emergence activity; they are applied to the soil after cultivation and effectively control germinating weed seeds. Examples are zimazine, Diuron etc.


  • PRE-PLANTING HERBICIDES: This can be a foliar; selective or non-selective herbicide, applied before the crop is planted. Examples are Glyphosate , Paraquat.
  • PRE-EMERGENCE HERBICIDES: These are applied in the soil before the emergence of weeds, immediately after cultivation e.g Galex  + Metolachar used for cowpea, Cotoran used for cassava etc. You can buy any of these Pre-Emergence Herbicides For Weeds Control
  • POST EMERGENCE HERBICIDES: These are applied after the emergence of weeds and can have both contact and systemic actions, but usually selective so as not to have phytoxicity effect on cultivated crop. Examples are Laddox in maize, Paraquat, Propanil, Glyphosate.  

Read also: List Of Herbicides Used For Weed Control On Maize Farm



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Author: Agbabiaka AbdulQuadri


  1. Thank you. Very educating but I have a question which goes thus:'Are non selective herbicides like glyphosate also systemic and/or used as a pre planting herbicide or not'? And also,how do we know how/when to apply the herbicides based on its mode of action?

  2. I have also ran into that trouble of not using herbicide at preemergence stage on my cassava farm. It's about 3weeks already after planting and I have agreed to doing manual weeding anyway. But am also asked to use herbicide after manual weeding. How do I apply it? Can I do it myself? How long will it keep the weed away after application?

  3. Is it possible not to use manual weeding at all for cassava intercropped with maize, I mean using herbicides only. What can I do to prevent the plants from being damaged during postemergence application of herbicides

  4. Is it possible not to use manual weeding at all for cassava intercropped with maize, I mean using herbicides only. What can I do to prevent the plants from being damaged during postemergence application of herbicides

  5. Very good write-up and a nice job you are doing here. Keep it up. I just harvested my maize and I want to kill off the weeds before planting cassava. What is the best herbicide combinations I can use please?

  6. Thank you very much. It is very possible you use only herbicides on your cassava farm but it has to start from land preparation. After clearing, ploughing and harrowing your land, you plant. immediately after planting you apply pre-emergence herbicides. this will keep your land off weeds for about 3months. by then, your cassava plants would have grown taller and able to suppress the weeds. you can't totally eradicate the weeds but what you are required to do is to suppress them greatly.

    i hope this helps. thanks.

  7. My cassava farm was weeded going to 3 weeks ago now. That was the first weeding after planting. Can i still use atrazine now to keep weeds away for the next 2 to 3 month to reduce cost incurred if manual weeding is applied? Thanks

  8. Hi, please I've got a question. Can you Convince me why i should mix altrazine xtra force and contact herbicide grass cutter on a just planted cassava farm (two days ago) is it good to mix the two or not to mix them after. I need your urgent reply, please.

  9. Cover fliting is done when the crops are still very young; you just cover all the plants preferably with plastic bowl, just the portion of the crops and spray your field. what you are preventing is contact of the chemical and your crops. i hope this helps.

  10. Cover fliting is done when the crops are still very young; you just cover all the plants preferably with plastic bowl, just the portion of the crops and spray your field. what you are preventing is contact of the chemical and your crops. i hope this helps.

  11. Pls i planted corn 2 weeks ago after plowing and am currently intercropping it wt cassava but i hv little weeds germinating around. Shld i just spray atrazine herbicide as am planting d cassava or spray afterd cassava has sprouted

  12. Plz I will like to know the selective chemical I can us for cassava.the farm has been hand weeded but the weed keep growing too fast.is there any chemical I can use to control the weeds?

  13. Weldone. I planted maize on my entire farm and cassava on half (bcos of stem shortage). I weeded 3 weeks ago. Now i want to plant d remaining cassava but weeds are up again. What chemicals do i use? 2 when do i apply it, b4 or after planting? Thanks

  14. Well sir I must say I enjoy reading your article. Pls what chemical can I use to kill the grass in front of my compound? No plants just only weeds. Pls tell me the name chemical and where to get it in lagos. I want a very strong chemical that will be able to kill all the grass. Thanks. Michael from Lagos.

  15. helo master quadri i really enjoy ur class how ever i cultivate entirely different crops compared to what every one has commented one , my plants are plantain, paw paw and pepper but i intend to plant plantain now and inter-cropped with cassava so i want to seek ur advice how do i go about the planting and when do i need to use herbicide or shld i separate the crops like i hv done b4 now and for my plantain hat is stand alone like 5 months now wch herbicides that is best for it to b used thanks

  16. Thank for your work here. Please am planning to cultivate pepper and water melon next season. Although they would be on different plots of land. Which herbicides can i use to adequately control weeds on these farms and should they be sprayed pre emergence?

  17. Thanks for your observation. Personally, am an advocate of organic farming, i sternly detest the use of chemicals, however, you would agree with me that some situations in farm require the use of chemicals. Chemical is very effective in controlling weeds and pest. Glyposate in unarguably the most recommended and most effective active ingredient in controlling weeds, that is why i tell people to use it. On the issue if its apparent danger, it has dosage farmers must adhere to. With the recommended dosage their apparent dangers are mitigated.

  18. Please I need your urgent help. I want to go into agriculture business for the first time and having 2acres which am planting cassava and maize, so I need procedure to follow in pre and post emergence in chemical method. Thanks

  19. Good day pls I just inter cropped yam,maize and cassava in my farm and they have started sprouting, which selective herbicide do I use and method of use thanks.

  20. Good day, i planted maize is about one month plus now and want to broadcast rice on the same land. What type of weed control should i use.

  21. Good morning, I have a plantain farm and I want to intercrop with watermelon, I have just weeded the place, whats the best herbicide to use and can I spray befor planing the watermelon or after planting the watermelon?

  22. Am in need of ur assistant and is there no any herbicides that will work for both maize and cassava for post planting herbicides. My farm was large and have used glyphosate with attrazine as pre planting herbicides but to my surprise after two weeks its look as if I didn't spray any herbicides. Then I apply labourers weeding which is hoeing in order to remove d broad leaves and d grasses but to my surprise the farm has also grow this same weeds and I used d farm last year which am using this yr again. Now am tired of weeding and initially I forgot to apply d maize herbicides b4 planting cassava. My question now is that haven't d agriculturist develop another herbicides for mixed cropping of cassava and maize or other herbicides which will kill any kind of herbicides on mixed cropping.

  23. for now, there is not herbicide for such. that is why it is recommended to apply herbicide immediately after harvest. you can con tact the admin for further assistance.

  24. I went to agrochemical dealers 4 pre emergence herbicideherbicide for late maize. I was given squash which contains 276 g of paraquat. When I asked the amount toto mix, I was asked to use 1 and half of the cup for 16L back sprayer. Pls hw right is that?

  25. Pls weeds have taken over my melon farm. Pls which herbicide will I use to control weeds now?

  26. Well done sir , could pre emergent chemical be used in un cultivated / plan land and be effective like that of cultivated land.

  27. Well done sir, please I was told that powdered chemical mixed with liquid one are effective in killing the weeds and their seeds. Can my crop seeds like maize and groundnuts be affected if I apply these chemicals two days after planting because I was told to apply first and wait for 10days before planting! Thanks.

  28. Well done sir, please can my crop seeds(maize and groundnuts) be affected if I apply powdered plus liquid chemicals like two days after planting. I was told to apply first and wait for 10days before planting. Thanks.

  29. Morning sir, pls, can my seedlings( maize and groundnuts) be affected if powdered chemical mixed with glyphosate are applied 1 or 2 days after planting? I was told to apply first and wait for 10days before planting. Thanks.

  30. Good evening sir. I applied force up herbicide on my farm of 21 days maise today. After getting home, someone told me that those maize will be destroyed. I didn’t spray on it but around it. Is it true? Thank you sir

    1. To avoid waste of time and money, as early as possible tomorrow, go and plant another maize on the field to replace the 21st day old one because the will definitely die within a week, if you plan another one immediately, you were good to go.

  31. I read your article and quite educative, where can I get the basegram for rice and maize you mentioned in the article?

  32. But sir, I didn’t let the herbicide touch the maize. I just sprayed on the surrounding weeds

  33. Good Morning.

    I am about to plant plantain suckers and I want to know which herbicide to use and how it should be used.

    Should I apply before planting the suckers or after planting the suckers.

    How should I apply it? Will there be an effect on the plantain if the herbicide touches it when applying?


  34. Thanks for your article. It really enlighten me more about Agriculture. I’m new in farming. I just prepare about 10 acres of land for watermelon farming. Please which herbicide is the best to use before planting watermelon to keep weed away from the farm till harvest period. Pls I need your help urgent. Regard Paul.

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