Selective and Non-Selective Herbicides - the Difference

06 Nov '18

man spraying herbicides on grassHerbicides are used to inhibit the reproduction and growth of weeds. These chemicals are classified depending on their usage. Weed control using herbicides follows a strict application when it comes to timing.

Some are applied before planting a seed, while some are used after the plant has already grown. Adequate weed control relies on proper timing.

How Herbicides Work

Chemicals can either work by contact or by systemic action. Fast-acting herbicides kill weeds upon application. They work ‘fast’ but the effect is limited.
When the chemical that is applied works systemically, it does not immediately kill the weeds. The plants absorb the herbicide first either through the roots or the waxy surface. When it spreads into all parts of the plant, all of the functions are shut down.

Types of Herbicides

Basically, there are two main types of herbicides - selective and non-selective. The former is used when inhibiting the growth of a specific weed, leaving the other plants unharmed. The non-selective variants kills all the plants it comes in contact with.

Selective Herbicides

This chemical is formulated to be extremely potent to specific types of plants only, such as grass and broadleaf weeds. However, it is not harmful to other plant species. When using selective herbicides, it’s important to read the product label to confirm it targets the type of plants you want to eliminate.
The effectiveness of its use is dependent upon the dosage and timing of the application. Here are some herbicides in the selective category:

  • Turflon Ester Ultra

This specialty post-emergent herbicide works best on broadleaf weeds and vines such as kudzu and ivy.

  • T-Zone SE

With the combination of chemicals, this selective variant covers a wide-spectrum of tough weeds. The Triclopyr component kills ground ivy, wild violet oxalis and wild blackberry. The Sulfentrazone chemical is responsible for the rapid weed elimination for species like spurge, white clover and dandelions.
The 2,4-D ingredient targets the growth regulator of plants causing curling and twisting of the weeds, which leads to death of the plant. Dicamba, the fourth component, is responsible for inhibiting growth of tough weeds as it reaches the leaves and roots.


Non-Selective Herbicides

This variant is designed to eliminate a broad range of weeds and plants. It works either by contact or systemic mode of action. Some of popular non-selective herbicides are the following:

  • Round-Up (Glyphosate)

This is a systemic, post-emergent herbicide which kills perennial weeds. One of the advantages of using this chemical is how toxic it is to plants but does not pose any harm to animals and humans.

However, because of its toxicity to broad range of plants, even a small amount of spray that drifts away can harm ornamentals nearby.

  • Reward

This is another post-emergent weed killer that works by direct contact. It can kill small, annual weeds rapidly. Small amounts of spray drift will not cause extreme harm to ornamentals.

This herbicide is not sensitive to temperature but is relatively dangerous to animals compared to Roundup-Pro.


The decision of which type to use depends on the type of plants you want to eliminate and if ornamentals are planted nearby. If weed elimination is not successful or you are uncertain how to do it, you can always ask help from a professional weed control service in your area.

Custom Weed & Pest Control has been in business since 1989, serving the greater Phoenix metro area for both residential and commercial. We offer organic, natural and chemical weed control, with customized service to meet your specific needs.

Related Page: Types of Herbicides

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