Systemic vs. Non-Systemic Pesticides: Understanding the Differences

Pesticides 

Pesticides are essential in contemporary agriculture, enabling farmers to safeguard crops against insects, fungi, and other pests. However, pesticides function differently and can generally be categorized into systemic and non-systemic (contact) types.

What Are Systemic Pesticides?

Definition

Systemic pesticides are taken up by the plant and moved throughout its vascular system, including the xylem and/or phloem.  

Mode of Action

After entering the plant, the chemical disperses to various parts such as roots, stems, leaves, flowers, and occasionally fruits. Pests consuming the plant absorb the pesticide and are exterminated.  

Examples include neonicotinoids (e.g., imidacloprid), systemic fungicides, and certain herbicides.  

Application Methods

Soil drenching, seed treatment, and foliar sprays that infiltrate plant tissues.  

Advantages 

  - Provides protection for new growth over time.  

  - Less reliant on spray coverage.  

  - Effective against concealed or sucking pests like aphids, whiteflies, and nematodes.

  Limitations

  - Possible risks to pollinators due to pesticide residues in nectar or pollen.  

  - Persistence in soil and water.  

  - Requires strict pre-harvest interval (PHI) compliance.  

What Are Non-Systemic (Contact) Pesticides?

Definition

Non-systemic pesticides remain on the plant's surface and do not penetrate internally.  

Mode of Action

These pesticides eliminate pests only through direct contact or by ingestion of treated surfaces.  

Examples include pyrethroids, copper fungicides, sulfur dust, and many traditional insecticides. 

 Application Methods

Foliar sprays, dusting, or surface coating.  

Advantages

    - Fast knockdown effect.  

  - Reduced risk of residues within edible plant parts.  

  - Suitable near harvest due to shorter persistence.  

 Limitations

   - Requires comprehensive coverage for effectiveness.  

  - Easily washed away by rain or irrigation.  

  - Offers limited protection for new plant growth.  

 Systemic Pesticides  

- Absorbed and circulate within plant tissues  

- Safeguard new growth  

- Effective against concealed/sucking pests  

- Longer duration, but poses risk to pollinators  

- Example: Neonicotinoids  

Non-Systemic (Contact) Pesticides  

- Remain on the plant surface  

- Immediate knockdown effect  

- Necessitate thorough coverage  

- Short-term protection, easily rinsed off  

- Example: Pyrethroids  

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