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Post-emergent Herbicides

Types of Post-emergent Herbicides

Post-emergent herbicides are used to kill the weeds that have already grown in the yard.  Some of the common types include liquid post-emergents, granular post-emergents, systematic post-emergents, contact post-emergents, selective post-emergent herbicides, and selective post-emergent herbicides. The ‘post’ in post-emergent herbicides signifies that these products are used to kill the weeds after they grow as compared to pre-emergent herbicides, which are used to prevent weeds from growing in the yard altogether. 

Lawn care is all in the details, and we take care of every single one to give you the lawn of your dreams. Contact us today!

These are classified into various categories depending on their mode of application, impact, and form. This article explains all these types of post-emergent herbicides in detail. You will also find information about the most commonly used herbicides, the common chemicals present in post-emergent herbicides, and the risks associated with post-emergent herbicides here. Let us start with the types of post-emergent herbicides.

1. Liquid post-emergents

Liquid post-emergents are post-emergent herbicides that come in the form of liquid concentrates or ready-to-use sprays. These liquid post-emergent concentrates need to be mixed with water in the right ratio according to the directions given on the product label before using them for effective control and to avoid burning any surrounding plants. After mixing, the mixture is poured into a hand pump or a backpack spray, according to the convenience of the person applying the post-emergent. Liquid post-emergents adhere to plants really well and therefore are effective in controlling weeds. 

The advantages of liquid post-emergents are that they stick to the weeds easily and can be applied to the weeds both when their leaves are dry and wet. Also, as they need to be sprayed, they allow more control for an even application. The disadvantage of using post-emergent herbicides is that they need to be mixed in the exact ratio mentioned on the label, or you might end up either burning your plants or not getting effective control of the weeds.

The cost of liquid post-emergent herbicides ranges from around $5 for a ready-to-use selective post-emergent herbicide that comes in a 32 oz spray bottle to around $200 for 2.5 gallons of non-selective systemic post-emergent liquid concentrate. The price can go higher depending on the brand, type, and range of control of the post-emergent herbicide.

 Liquid post-emergents

2. Granular post-emergents

Granular post-emergents are post-emergent herbicides that come in the form of pellets or granules that are coated with weed-control chemicals. These granular post-emergent herbicides are applied to the weeds using a handheld spreader, push spreader or the more accurate ride-on spreader. Like liquid post-emergent, granular post-emergents can also be applied to a broad spectrum of weeds. For specific weeds, the product label will tell you its range of effectiveness.

The advantages of using granular post-emergent herbicides are that no accurate measurements are required, unlike liquid post-emergent, and they are easy to use for beginners. The disadvantages of using granular post-emergent herbicides are that they don’t stick to the leaves of the weeds as easily as liquid post-emergents do. For some granular post-emergents, you need to wet the ground before applying to ensure effective control. 

The cost of a granular post-emergent herbicide is around $18 for a 5 lb bag of selective post-emergent that is said to cover 2500 square feet. The price can vary depending on the brand, type of application and impact and quantity of the granular post-emergent herbicide.

3. Systemic post-emergents

Systemic post-emergents, also known as translocated herbicides, which are designed to be absorbed by the vegetative parts of the weed during photosynthesis. After absorption, they travel from the roots through the entire structure of the plant, destroying it completely. They are slow to act compared to contact post-emergents, but they destroy the entire weed plant along with its root system, which prevents the weed from sprouting in your yard again. This is the reason systemic post-emergents are mostly used to kill perennial weeds like dandelion and ground ivy to prevent the weed problem from recurring the next year. 

The advantages of using systemic post-emergent herbicides are that they kill the entire weed plant along with its root system, eliminating the chance of the weed sprouting in your yard again the next year, and they are effective against weeds that have developed resistance to contact herbicides. Also, in the long run, systemic herbicides are more cost-effective as they do need repeated applications to be effective. The disadvantage of using systemic post-emergent herbicides is that they are slow to take effect, and it might take seven days for their impact to be visible.

A good systemic post-emergent herbicide costs around $18 for a 32 oz ready-to-use spray bottle of systemic post-emergent application. The price will vary depending on the quantity, type and brand of the product.

Systemic post-emergents

4. Contact post-emergents

Contact post-emergents, as their name suggests, are post-emergent herbicides that are designed to kill the weed plant on contact. Unlike systemic post-emergent, they are not absorbed into the plant, and hence they do not kill the roots of the plants but kill the foliage of the weeds they are applied to. For most weeds, the death of the foliage means the death of the plants, as there are no leaves available for photosynthesis in this scenario. Since contact post-emergents do not kill the roots of the weeds, they are used to control annual weeds like crabgrass and nettle, as these weeds do not recur year after year after establishing roots. 

The advantages of using contact post-emergent herbicides are that they are very quick to act, and you can see the results immediately. They are also cheaper than systemic herbicides and are a good option for spot treatments. The disadvantage of using contact post-emergent herbicides is that they do not kill the roots of the weed, which increases the chances of the weed appearing in your yard again next season. 

A good contact post-emergent herbicide costs around $8 for a 16 oz liquid concentrate of contact post-emergent herbicide. The price will vary depending on the number of listed weeds, brand and quantity of the product.

5. Selective post-emergent herbicides 

Selective post-emergents are the post-emergent herbicides that are formulated to only target the weeds they are labeled for and not affect the surrounding desirable plants and turfgrass. In other words, the chemical formulation of selective herbicides is designed to be potent for some plant species and safe for others. A simple example of this is the Turflon Ester Ultra, which is a selective post-emergent herbicide that kills broadleaf weeds like yellow woodsorrel and wild violet and vines such as ground ivy and kudzu. Selective herbicides are the best option to use in areas where you cannot avoid turfgrass and other desirable plants and where you have identified the weeds that need to be removed.

The advantage of using selective post-emergent herbicides is that they are safe to use around turfgrass species and plants that are not listed on the product label. This means that if this herbicide spray drifts to the nearby plants or if you happen to spill this herbicide on your turfgrass, it will not kill them. The disadvantages of using selective post-emergent herbicides are that they cannot be used for blanket control of weeds as all the weeds present in one area might be controlled by the same product, and they require multiple applications to be effective. 

A good selective post-emergent herbicide costs around $18 for a 32-ounce liquid concentrate of selective post-emergent herbicide. The price will vary as the quantity and brand change.

Selective post-emergent herbicides

6. Non-selective post-emergent herbicides 

Non-selective post-emergents are post-emergent herbicides that kill every kind of vegetation that they come in contact with. Therefore, apart from noxious weeds, non-selective post-emergents will also kill vegetation, such as shrubs, grass, bushes, flowers, and any other desirable plant that they touch. These herbicides are powerful, which makes them a good option to use around fences, in driveways, and on sidewalks for controlling weeds. As these non-selective post-emergent kill plants indiscriminately, they are mostly suitable for use in large, unmanaged areas or in case of severely infested areas where the surrounding turfgrass cannot be salvaged. 

The advantages of using non-selective post-emergent herbicides are that they can be used around hardscapes like driveways and sidewalks, one application provides effective control, and this eliminates the need for multiple applications, thus proving to be more cost-effective. The disadvantages of using non-selective post-emergent herbicides are that they kill all plants indiscriminately. Weeds and desirable plants alike are eliminated and these products can harm the overall health of your landscape if they are not applied correctly.

A good non-selective post-emergent herbicide costs around $13 for more than one gallon of non-selective liquid concentrate. The price will vary depending on the brand and quantity of the product.

Which type of Post-Emergent Herbicides is commonly used?

The most commonly used post-emergent herbicides are systemic selective liquid post-emergent herbicides which are a combination of some of the above-mentioned post-emergent herbicide types. Liquid herbicides are most commonly used by professional as well as amateur gardeners and landscapers as they provide more control for an even application. 

Selective herbicides are preferred over non-selective herbicides because they do not harm the surrounding desirable plants and turfgrass, preventing you from having to replant the entire area, which will be required if you use a non-selective herbicide. Therefore, non-selective herbicides are only used if the severity of the infestation demands it. Systemic herbicides provide more effective and long-term control compared to contact herbicides and therefore are preferred over contact post-emergents to control hardy weeds.

For more information on the post-emergent products that are effective on lawns, read Eden’s article – Post-Emergent for Lawns.

Which type of Post-Emergent Herbicides is expensive?

Selective systemic post-emergent herbicides are expensive compared to contact and non-selective herbicides, and these come in the form of liquid concentrates. As mentioned above, these types of post-emergent herbicides are the most effective, and this factor contributes to their higher price. Also, granular post-emergents are more expensive than liquid post-emergent herbicides. 

An example of this would be Blindside Herbicide WDG 8 oz and Tenacity Turf Herbicide 8 oz, both of which are systemic selective post-emergent herbicides (liquid concentrates) and are priced at $143.50 and $62.98 on Amazon, respectively. Monterey LG5328 Getter, Post Emergence Herbicide for Grass Weeds, 8 oz,  is a selective contact post-emergent priced at $34.97 for the same quantity on Amazon. Also, Spectracide 66001 Weed & Grass Killer Concentrate, 16 oz is a non-selective contact post-emergent priced at $ 7.58 on Amazon for a higher quantity. Looking at these prices we can see that the granular post-emergent herbicides are priced higher than the liquid ones.

What are the common chemicals in Post-Emergent Herbicides?

Post-emergent herbicides are formulated to target existing or established weeds, and therefore, all products contain some common chemicals. Eden lists the chemicals that are commonly found in post-emergent herbicides.

Dicamba: It is a selective post-emergent herbicide that works best on broadleaf weeds, both perennial and annual, like clover, spurge, dandelion, thistle, etc.

Glufosinate: Glufosinate is a non-selective, contact, broad-spectrum post-emergent herbicide that is used to control weeds such as morning glory, yellow nutsedge, 

Bentazone/Bentazon: Bentazone is a selective post-emergent herbicide that is safe to use on plants like maize, peanuts, peas, alfalfa, pepper, etc., as well as turf and lawns. 

Glyphosate: Glyphosate is a selective systemic post-emergent herbicide that is used to control broadleaf weeds and grasses like thistle, dandelions, and grassy weeds like bluegrass.

Fluazifop: Fluazifop is a selective post-emergent herbicide that provides good control of grassy weeds like witchgrass, foxtail weeds, barnyard grass, crabgrass, etc., but is not as effective on broadleaf weeds.

Methanearsonate: Methanearsonate is a selective post-emergent herbicide that is mostly used to control nutsedge and crabgrass.

If weeds are taking over your landscape and impacting its health and appearance, you can contact Eden. Our professional landscapers will identify the weeds present in your landscape and develop control methods accordingly. You can also contact Eden if you have any other landscaping query.

Lawn care is all in the details, and we take care of every single one to give you the lawn of your dreams. Contact us today!