Herbicides can be define as chemicals used to kill or control unwanted plants, known as weeds.Some herbicides are used before planting (pre-emergent) to prevent weeds from growing, while others are used after weeds have appeared (post-emergent).

1. Selective Herbicides: These herbicides target specific types of weeds without harming the desired crops. For example, they might kill broadleaf weeds but leave grasses unharmed.


2. Non-Selective Herbicides: These herbicides kill all plants they come into contact with, used for clearing areas where no vegetation is wanted.


3. Pre-Emergent Herbicides: Applied before the weeds have sprouted, these herbicides prevent weed seeds from germinating and growing.


4. Post-Emergent Herbicides: Used after weeds have already sprouted, these herbicides kill existing weeds.


5. Contact Herbicides: These herbicides kill only the parts of the plant they touch, typically the leaves and stems, and are effective against annual weeds.


6. Systemic Herbicides: These herbicides are absorbed by the plant and travel throughout its tissues, killing the entire plant, including roots. They are effective against perennial weeds.


7. Residual Herbicides: Also known as soil-applied herbicides, these remain active in the soil for a period, providing ongoing weed control.


8. Organic Herbicides: Made from natural substances, these herbicides are less harmful to the environment and can be used in organic farming.


9. Synthetic Herbicides: These are chemically manufactured and widely used for their effectiveness and reliability in conventional farming.


10. Selective Grass Herbicides: Specifically target grass species without affecting broadleaf plants, useful in crops like soybeans or tomatoes.

1. Spraying: Herbicides are mixed with water and sprayed directly onto the leaves of weeds. This method is common for both pre-emergent and post-emergent herbicides.


2. Soil Application: Herbicides are applied directly to the soil to control weeds before they emerge. This is often used with pre-emergent herbicides.


3. Foliar Application: Herbicides are sprayed onto the leaves of plants. This is particularly effective for post-emergent herbicides that need to be absorbed by the plant.


4. Granular Application: Herbicides are applied in a granular form, spread evenly over the soil. Rain or irrigation dissolves the granules, allowing the herbicide to work.


5. Spot Treatment: Herbicides are applied only to specific, targeted areas where weeds are present. This is often used for non-selective herbicides to avoid damaging desirable plants.


6. Broadcast Application: Herbicides are applied evenly over a large area, either by hand or with machinery. This method is used for both pre-emergent and post-emergent herbicides.


7. Wicking or Wiping: Herbicides are applied using a wick or cloth that wipes the herbicide onto the weeds. This method is useful for treating weeds among crops without harming them.


8. Injection: Herbicides are injected directly into the soil near the roots of the weeds or into the plant itself. This method is used for controlling deeply rooted perennial weeds.


9. Aerial Application: Herbicides are sprayed from an aircraft, suitable for large fields or difficult-to-reach areas. This method is efficient but requires precise application to avoid drift.


10. Drip Irrigation: Herbicides are mixed with water and delivered through a drip irrigation system. This method ensures the herbicide reaches the soil directly around the plants.

1. Herbicides can contaminate soil, water, and air, harming plants, animals, and ecosystems.


2. Exposure to herbicides can cause health problems in humans, including skin irritation, respiratory issues, and long-term diseases like cancer.


3. Herbicides can accidentally harm plants that are not weeds, including crops and beneficial plants.


4. Overuse of herbicides can lead to weeds becoming resistant, making them harder to control over time.


5. Herbicides can run off into rivers, lakes, and groundwater, affecting drinking water and aquatic life.


6. Frequent herbicide use can harm soil organisms and reduce soil fertility over time.


7. Herbicides can negatively impact birds, insects, and other wildlife, disrupting ecosystems.


8. Herbicides sprayed on fields can be carried by the wind to nearby areas, affecting non-target plants and ecosystems.


9. Herbicide residues can remain on crops, potentially entering the food chain and affecting food safety.


10. Over-reliance on herbicides can be expensive for farmers, particularly if resistance leads to the need for more or stronger herbicides.