What’s the Difference Between Systemic and Contact Herbicides?

Herbicides are crucial in managing weeds and unwanted plants in agricultural practices. Systemic and contact herbicides are two primary types of herbicides commonly used in farming. These herbicides differ in their work, application methods, and effectiveness in controlling specific types of weeds. Understanding the distinctions between systemic and contact herbicides is essential for farmers and gardeners who want to optimize their weed control methods and enhance their agricultural productivity.

This blog’ll explore the differences between systemic and contact herbicides, the science behind their action, and how they fit into modern farming practices. We’ll also discuss the benefits and drawbacks of each and provide helpful guidance on choosing the right herbicide for your needs.

What Are Systemic Herbicides?

Systemic herbicides are designed to be absorbed into the plant and move throughout its tissues. This means that the herbicide is transported through the plant’s vascular system, ultimately affecting the plant’s internal processes. When applied, these herbicides are absorbed through the leaves, stems, or roots and then circulate through the plant, interfering with key biological functions. Over time, this internal disruption stunts the plant’s growth, eventually causing it to die.

A popular dry systemic herbicide that utilizes this mechanism is Glyox ammonium - salt of glyphosate 71% SG, a widely used formulation in farming. The formulation is particularly effective for controlling perennial weeds and unwanted grasses. Understanding the proper dosage of ammonium salt of glyphosate 71% SG per litre is essential to ensure its effectiveness in killing target plants while protecting non-target species. By following the manufacturer’s recommended dosage and usage guidelines, farmers can achieve optimal results in weed management.

• Usage in Agriculture: Systemic herbicides like ammonium salt of glyphosate 71% SG are widely used in large-scale farming for weed control. These herbicides are especially effective on deep-rooted weeds that are difficult to manage with other methods.

• Mode of Action: Once absorbed, systemic herbicides can travel through the plant's vascular system, attacking vital processes such as photosynthesis and protein synthesis. This ultimately leads to the plant’s death.

Systemic herbicides are advantageous because they target the plant’s internal systems, allowing them to kill both the visible portions and the roots of the plant, ensuring long-lasting results. However, their action can sometimes take several days or even weeks to manifest, depending on the weed type fully.

What Are Contact Herbicides?

Unlike systemic herbicides, contact herbicides only affect the parts of the plant they come into direct contact with. These herbicides work by causing immediate damage to the plant tissues where they are applied, typically through cell membrane disruption. Contact herbicides do not enter the plant’s vascular system and thus do not spread internally. As a result, they generally kill only the parts of the plant they touch, leaving the roots intact.

Contact herbicides are more suited for annual weeds, fast-growing plants, and weeds with shallow root systems. They are typically applied to the plant's foliage, and their effect is usually visible within hours. However, contact herbicides are not as effective on perennial weeds with deep root systems, as they do not reach the roots where regeneration can occur.

• Immediate Action: The results of contact herbicides are typically visible quickly, often within a few hours of application.

• Limited Effect: These herbicides do not provide long-term control because they only target the plant’s visible tissues. Weeds may regrow if their roots remain intact.

Although contact herbicides may not be as effective on deep-rooted weeds, they are often preferred for use in situations where rapid action is needed, such as in non-crop areas or in pre-planting conditions.

Key Differences Between Systemic and Contact Herbicides

To better understand which herbicide might be best for your specific agricultural needs, let’s break down the main differences between systemic and contact herbicides:

Mode of Action

• Systemic Herbicides: These are absorbed by the plant and move throughout its vascular system, affecting the visible parts and the roots.

• Contact Herbicides: These only impact the plant parts they directly contact, leaving the roots unaffected.

Target Weeds

• Systemic Herbicides: Effective against perennial weeds, deep-rooted plants, and those that have a tough growth cycle.

• Contact Herbicides: Best used on annual weeds, fast-growing plants, and those with shallow root systems.

Speed of Action

• Systemic Herbicides: Slower acting, with the effects often taking several days to a few weeks to fully manifest.

• Contact Herbicides: Fast-acting, with visible results often seen within hours or days of application.

Persistence

• Systemic Herbicides: Provide longer-lasting control as they target the entire plant, including its root system.

• Contact Herbicides: Do not offer long-term control, as they only kill the exposed parts of the plant and do not affect the roots.

Application Methods

• Systemic Herbicides: Can be applied to leaves, stems, or roots, and they will be absorbed and transported throughout the plant.

• Contact Herbicides: Applied to the leaves or stems of the plant, where they cause immediate damage.

Benefits of Systemic Herbicides

Systemic herbicides are highly effective for managing stubborn and invasive weeds. Their ability to kill both the visible plant and the root system makes them particularly useful for long-term control of perennial weeds and invasive plant species.

• Effectiveness on Perennials: Systemic herbicides can target weeds that other herbicides might struggle to control due to their deep root systems.

• Long-lasting Results: These herbicides offer extended protection by attacking the plant’s internal systems, reducing the need for frequent reapplications.

In large-scale agriculture, systemic herbicides like ammonium salt of glyphosate 71% SG are commonly used to keep fields clear of weeds and prevent them from competing with crops for nutrients, water, and sunlight. Systemic herbicides can help boost agricultural productivity and ensure higher crop yields when used correctly.

Benefits of Contact Herbicides

While contact herbicides are not as effective on deep-rooted or perennial weeds, they do offer several advantages in specific situations:

• Fast Results: Contact herbicides work quickly, providing rapid control of weeds in areas where speed is essential.

• Targeted Applications: These herbicides are useful for spot treatments, such as when weeds are located in small or isolated areas of the field or garden.

• Low Risk of Resistance: Contact herbicides generally target the external parts of the plant, which reduces the likelihood of weed resistance developing in the same way it might with systemic herbicides.

Farmers often use contact and systemic herbicides to create a comprehensive weed control strategy. By using both types of herbicides, they can control a broader range of weeds and prevent herbicide resistance from developing.

Which Herbicide Should You Use?

The decision between systemic and contact herbicides depends mainly on the type of weeds you are targeting, the timing of the application, and your overall weed management strategy. Here are some factors to consider:

• For Perennial Weeds with deep roots, Systemic herbicides are typically the best choice, as they can kill the entire plant, including the roots.

• For Annual Weeds or Fast-growing Plants: Contact herbicides are effective for quickly controlling annual weeds or fast-growing plants without deep root systems.

• For Speedy Action: If you need quick results and want to eliminate weeds quickly, contact herbicides can damage the plant immediately.

• For Long-term Control: Systemic herbicides are the better option for long-lasting weed control. They target the plant’s internal systems and provide more enduring results.

The Future of Herbicide Use in Agriculture

In contemporary agriculture, the application of contact and systemic herbicides remains crucial. Herbicides' function in weed control is probably going to shift as farming methods and technology advance. For instance, precision agriculture methods that target certain field regions using GPS and data analytics may assist increase the effectiveness of herbicide application while lowering overall usage.

Furthermore, new herbicide formulations are always being created to solve issues like herbicide resistance and environmental problems. Farmers can choose which herbicide to use and when to apply it more intelligently if they keep up with the most recent advancements and best practices.

Frequently Asked Questions (FAQs)

1. How can I determine which herbicide to use?

The type of herbicide you choose depends on the type of weed you’re targeting. Systemic herbicides are best for deep-rooted, perennial weeds, while contact herbicides are effective for annual weeds and quick treatments.

2. Are systemic herbicides safe to use in farming?

 According to the manufacturer's instructions, systemic herbicides, such as ammonium salt of glyphosate (71% SG), are safe for use in agriculture. Always follow safety guidelines to minimize risk to human health and the environment.

3. How long do systemic herbicides take to work? 

Systemic herbicides can take anywhere from a few days to several weeks to show visible results, depending on the type of plant and environmental conditions.

4. Can I mix systemic and contact herbicides? 

Many farmers combine systemic and contact herbicides to achieve broader weed control. This combination can address various weed types and improve overall effectiveness.

Stay Informed and Make the Right Choice

Understanding the difference between systemic and contact herbicides is key to making informed farming weed management decisions. Choosing the right herbicide for the right situation can optimize your weed control efforts, increase crop yields, and contribute to sustainable agricultural practices. Whether you're dealing with deep-rooted perennial weeds or fast-growing annuals, a herbicide solution can help. Stay informed about the latest trends, products, and practices in weed management to ensure a successful farming operation for years to come.