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October 27, 2022 4 min read

Herbicides are a broad category of pesticides used to kill or control undesired plants or weeds. There are many different types of herbicides, each of which works in a unique way. From pre-emergent herbicides that prevent weeds from germinating to post-emergent herbicides that kill existing weeds, these products are an important part of weed control and management.

In this blog post, we'll take a closer look at how herbicides work so that you can make an informed decision about which type of lawn or garden herbicide is right for your needs.

How Do Herbicides Work?

Herbicides work by targeting specific plants and interfering with their ability to grow or reproduce. They play a critical role in controlling grassy weeds, broadleaf weeds, woody brush, and other undesired plants or weeds. They're used on both residential and commercial lawns, golf courses, farms, gardens, sports fields, and any other green spaces where weed control is necessary.

With all the different types of herbicides available, it's critical to understand the different ways they work. The four main ways that herbicides work are either by inhibiting photosynthesis, preventing seed germination, stopping plant growth, or killing the roots of plants. 

Inhibiting Photosynthesis

Photosynthesis is the process that plants use to convert sunlight into energy. Some herbicides work by inhibiting this process, which prevents the plant from being able to produce food and eventually kills it. This type of herbicide is known as a photosystem II inhibitor.

There are two types of photosystem II inhibitors:

  • Non-selective photosystem II inhibitors - These will kill any plant they come into contact with, including crops. 
  • Selective photosystem II inhibitors - These will only kill certain types of plants. 

Stopping Plant Growth

Some herbicides work by stopping the plant from being able to grow. This can be done in several ways, including:

  • Inhibiting cell division
  • Preventing the formation of new cells
  • Interfering with the plant hormone auxin

Killing the Root System

Still wondering how do herbicides work? Another way is by killing the plant's roots. This prevents the plant from being able to take up water and nutrients from the soil, which eventually kills it. If the roots are killed, the plant will eventually die.

Preventing Seed Germination

Some types of herbicides can prevent seeds from germinating. This means that the plant doesn't even have a chance to grow before it is killed.

Modes of Action for Herbicides

As mentioned above, herbicides work by either killing the plant outright or preventing the plant from being able to grow. The mode of action of an herbicide is the specific way in which it kills or prevents the growth of plants. There are four main modes of action for herbicides: 

  • Contact herbicides - These kill the parts of the plant they come into contact with. They are generally fast-acting but only effective on small plants since they must come into direct contact with the leaves or stems. 
  • Systemic herbicides - These types of herbicides are absorbed by the plant and then moved throughout the plant's tissues. They can be effective on both small and large plants. 
  • Translocated herbicides - These are absorbed by the leaves or roots and then moved to other parts of the plant, such as the stems or leaves. They are most effective on larger plants. 
  • Selective herbicides - These kill certain types of plants while leaving others unharmed. This type of herbicide is often used in agricultural settings to kill weeds without harming crops. 

Herbicide Resistance

Now that we’ve answered the question of how do herbicides work, one of the biggest challenges facing farmers today is herbicide resistance. This is when a plant becomes resistant to a herbicide that was previously effective at killing it. When this happens, farmers have to use more herbicides or even different types of herbicides, which is costly and can harm the environment.

There are several ways that plants can become resistant to herbicides:

  • Mutations - This is when a plant's DNA changes and it becomes resistant to the herbicide.
  • Cross-resistance - This is when a plant is resistant to more than one herbicide because it has the same mode of action.
  • Target site resistance - This is when the herbicide binds to a different site on the plant's enzyme, which prevents it from working.

To combat herbicide resistance, farmers must constantly monitor their crops and rotate their herbicides. This means using a different type of herbicide with a different mode of action each time, which reduces the chances of the plants becoming resistant.

Herbicide Application
Women Gardening

Herbicides can be applied in different ways, depending on the type of herbicide being used and the size of the area that needs to be treated. Small areas like residential lawns and gardens can be treated with hand-held sprayers or portable backpack sprayers, while large areas like sports fields or commercial green spaces may require the use of agricultural equipment such as commercial-grade sprayers or even tractors.

Herbicide application should always be done according to the manufacturer's instructions provided with the type of herbicide you buy. This includes wearing the proper safety gear, such as gloves and a face mask, to protect yourself from exposure to the herbicide. It's also important to ensure that you don't apply more herbicide than is necessary, as this can lead to environmental contamination and harm non-targeted plants and animals. 

Learn More From Experts at DIY Pest Warehouse

Herbicides are an essential tool for lawn and garden weed control, but before using them, it's important to understand how herbicides work. This is critical when it comes to targeting specific weeds while also protecting your family, pets, and the environment. At DIY Pest Warehouse, we have a wide selection of herbicides that can be used for everything from killing weeds in your garden to controlling plant growth around your home.

Our experts can provide you with everything you need to know about using herbicides, including which types of herbicides are best for your specific needs and how to apply them safely and effectively. Contact us today to learn more.