Wondering what the best weed killer is for thistle? These herbicides should kill both roots and seeds, which are the primary spreading of this weed.

Thistle has an extensive root system that adapts to mechanical, biological, and chemical control measures.

Herbicide for thistles must also be capable of d destroying underground roost and growth structure to prevent this notorious weed from re-sprouting.

Moreover, a thistle herbicide’s persistence is 100% imperative to kills these aggressive and creeping weeds to the roots.

How To Select The Best Weed Killer & Preventer For Thistle

Although there are hundreds of weedkiller on the market, getting the most appropriate product to control thistle in your yard or lawn remains to be a hard nut to crack. Additionally, there are hundreds of factors to consider before selecting thistle herbicide as expensive, generic, organic, and counterfeit products on the market.

Here are the most common and appropriate things you should consider before choking out any product from the market.

Selective Herbicide For Thistles

Thistles are a broadleaf weed that has a deep roots system. Therefore when controlling these notorious weeds in your lawn, consider going for a product that kills thistle while supporting grass growth.

Additionally, a selective thistle herbicide kills both the roosts and the entire thistle plant without causing any collateral damage to your lawn, such as leaving behind yellow and brown patches—Roundup Pro Weed Killer Concentrate was our editor’s pick of selective thistle weed killer.[table id=12 /]

Non Selective Herbicide For Thistles

 Next up, when killing thistle and other plants or grass in your lawn or yard, a non-selective herbicide will work great. Non-selective thistle herbicide kills any plant they come into contact with. This herbicide offers an excellent ground clearing option when preparing new land or renovating your lawn or driveway infested with thistle.

Liquid Weed Killers For Thistles

There are hundreds of liquid weed killers that are compatible with thistles, but Quali-Pro Prodiamine 65 WDG was our editor’s pick. The most exciting thing about liquid weed killers is that they are easy to formulate and easy to use.

Liquid thistle herbicides formulating can be done through direct drenching to the ground or through spraying. Consider going for a liquid product that is easy to blend with other agricultural products such as fertilizers or even fungicide, such as Paraquat, Diaquat, and Bromacil.

Granular Weed Killers For Thistles

Granular weed killers for thistles are not only easy to formulate but also more effective. The granular herbicide does not require mixing or measuring, as broadcasting them around the base of your target weed is more than enough.

Moreover, the granular herbicide is equally effective as they can kill thistle weeds on contact. Snapshot 2.5 TG took our editor’s favorite position of Granular yet Pre-Emergent thistles Herbicide while on the other hand; Spectracide Weed Preventer Granules was our top granular – yet an efficient post-emergent.

Pre-Emergent Herbicides For Thistles

In case your lawn already has thistles seeds, then pre-emergent herbicide will work best. The mode of action of pre-emergent herbicide is to create a thin film on the soil surface, thus preventing thistle seeds from germinating.

Quali-Pro Prodiamine 65 WDG was our favorite pre-emergent weedkiller for thistles. Pre-emergent thistle weed killers also play a huge role in controlling thistle in your lawn just before your newly planted grass seeds emerge.

For quick results when using a pre-emergent herbicide, consider going for products with Simazine or Atrazine as their primary ingredients.

Post -Emergent Herbicide For Thistles

When controlling newly germinated thistle weed plants consider going for post-emergent herbicides such as Compare-N-Save Broadleaf Weed Killer.

Additionally, the ingredient that should be active in post-emergent herbicides should be either 2-4-D or dicamba to effectively kill thistles and their roost.

Thistles post-emergent herbicide is also a quality product that prevents thistle from germinating on your lawn after your grass or foot plot seeds emerge. 

Review: 7  Best Weed Killer For Thistle In December In 2024

1.Quali-Pro Prodiamine 65 WDG Canadian Thistle Weed Killer

Despite being a chemical strategy for dealing with thistles, Quali-Pro Prodiamine 65 WDG   is both pet and an eco-friendly product. It consists of 65% Prodiamine as the only active ingredient; thus, it kills thistles to the roots. It kills weed in your lawn by causing systemic damage, hence our best weed killer for Canadian thistle.

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The 65% prodiamine ingredient is designed to kill the broadleaf weed, such as Canadian thistles, nettles, and chick weeds on contact. Interestingly the ready-to-use formula allows you to only add the content of the 4.99 pounds bottle to a sprayer and top it up to the mark with tap water.

This Quali-Pro Prodiamine is 100% designed to be compatible with Canadian thistle growing on the walkway and driveway cracks. It kills all broadleaf weeds on contact. Additionally, it comes with a quality container, thus helps in keeping the Quali-Pro away from moisture.

Moreover, by being a pre-emergent herbicide, it controls Spurge, Annual bluegrass, Henbit (Poa annua), Chickweed, Knotweed, and Foxtail flexible herbicide, Quali-Pro Prodiamine can control Canadian thistle in both spring and fall seasons.

2.Spectracide Weed & Grass Russian Thistle Weed Killer, Ready-To-Us

Spectracide for thistles is another excellent Russian thistle weed killer option, which took our second position. Like Quali-Pro Prodiamine 65 WDG, spectracide is a non-selective weed killer that eradicates both thistles and grass and prevents dead weeds from re-emerging.

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The 0.12% Diquat dibromide active ingredient allows spectracide to target Russian thistle roots and prevent them from re-growing accurately. By also being a quality pre-emergent weedkiller, spectracide can prevent thistle seeds from germinating by creating a protective barrier on the ground for over three months (90 days).

However, unlike Quali pro, Spectracide herbicide kills young and mature thistle weeds just three hours after formulation. Fortunately, Spectracide thistle herbicide has a non-staining formula. Hence it will not stain your work gear or your driveway pavements.

But why outer runner-up thistle killer, not the editor’s pick? Firstly, Spectracide herbicide only works effectively at 60 degrees Fahrenheit, unlike Quali-pro, which works flawlessly in warm and cold climates.

3.Monterey LG 5130 Weed Killer For Bull Thistle

Monterey LG 5130 Weed Herbicide is an excellent product for eliminating bull thistle while on budget. It kills broadleaf weed such as chickweeds, nettles, thistles, and grass varieties such as crabgrass, panicum, and foxtail.

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Bull thistle is commonly known as it produces hundreds of seeds that have a high germination rate. Interestingly, Monterey LG 5130 features a quality water formulation, which turns it to be a quick-acting weedkiller.

Another good thing about this product is that the 3 oz. Per bottles have a better ability to kill bull thistles in an area of over 5,000 to more than 10,000 sq. ft.  For instant Bull thistle killing ability, consider maintaining Monterey herbicide application rate of 3 oz. Per every 1,000 sq. ft. covered with bull thistles.

The Oryzalin 40.4% ingredient present allows this weedkiller to be a perfect product for complexly killing bull thistles, weeds, roost, and seeds. Interestingly Oryzalin 40.4% allows this weedkiller to remain useful for months even after tiling your yard. However, to some extent, Monterey is a toxic bull thistle weed killer as it has Oryzalin 40.4%, which causes harmful congenital disabilities to both pets and human beings.

4.Bonide (BND7464) – Burnout Concentrate

Fourth on our list finds an easy to use weed killer for eradicating thistle weeds in the grass of your lawn and brushes from bonide. Being anon selective herbicide bonide is an efficient ground clear option for regions that hundreds of thistle weeds are emerging.

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After formulating this weedkiller, for significant results, consider maintaining an application rate of concentrate mix formula of 8 fluid ounces Bonide Burnout Concentrate in every 24 ounces of pure or tap running water.

Many homeowners and landscapers find thistle to be challenging to control as they have a deep root system. Thanks to a 0.1% Sulfentrazone and a 0.2% prodiamine ingredient, they enhance the thistle root killing ability of bonide burnout.

Additionally, Sulfentrazone and prodiamine ingredients disrupt the photosynthesis capability of thistles, thus killing them instantly. It also can remain active even under 40 degrees Fahrenheit, hence an outstanding fence line, driveway, and walkway thistle killing strategy.

5.Roundup Pro Non-Selective Thistle Weed Killer Concentrate, 2.5 Gal

Wondering if round up will kill thistle and their roots? Then find Roundup Pro Weed Killer Concentrate. Furthermore, the 41% Glyphosate ingredient present ensures that round up pro can kill a broad spectrum of weeds.

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This product is a non-selective herbicide. As a result, it kills broadleaf weed and different varieties of contact. It comes with quality surfactant making it to be compatible with both wet and warm-season weed varieties.

It is also a fast-acting herbicide; hence the 2.5 Gal acts as a quality ground clear option for grass and thistle in an area of over 435,600 sq. ft.  The 41% Glyphosate gives round up pro the non-selective weed killing characteristic.

Three hours after formulating this herbicide, expect to see wilting and yellowing of thistle leaves. Round up inhabits enzyme production by thistle, thus preventing them from producing enough amino acids, which is vital for their survival, killing them instantly. The surfactants present offer additional burn out ability, thus improving its overall thistle weeds killing performance.

6.PBI Gordon Trimec Broadleaf Classic Herbicide

Stop thistle weed from lowering your lawn’s quality and appearance with this PBI Gordon Trimec Herbicide, which is compatible with all broadleaf weeds.

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Unfortunately, thistles have deep roots and also produce more seeds making them challenging to control. Luckily, PBI Gordon Trimec has 18.74% 2, 4-D, dimethylamine salt, which effectively kills both show and depth thistle roots.

Also, it comes with dicamba as an additional ingredient hence kills thistle weeds on contact. The dicamba ingredient present also gives this weed killer enough power to effectively kill both thistle seeds and root.

To get a quick result, either when killing thistles in a large or a small lawn/yard, consider maintaining an application rate of 0.37 – 0.75 oz  PBI Gordon per 1,000 sq. ft.

It also comes with anon staining formula, which does not expose your work gear, such as boot and f gloves, to collateral damage. Although PBI Gordon Trimec features a non-burning and non-staining formula, it kills both young and mature thistle weed plants effectively.

7.Preen 2464127 Garden Thistle Weed Preventer,

Taking our last position, find Preen Weed Preventer, which prevents thistle seeds from germinating. Interestingly, this product is kids and pets friendly as a result. It is safe to use around the household.

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Preen Weed Preventer is also an organic product. As a result, it does not release harmful aerosol or carbon compounds to the environment, making it an eco-friendly weed preventer.

The only downside of Preen Weed Preventer is that it does not have existing thistle weeds. It comes with a quality container that can make a perfect potting container for shallow root flowers and tree fruits.

Despite Preen Weed Preventer coming in an 8.1 pounds container, it has a better ability to kill thistle in a wide area of over 2,560 sq. ft.  it is a dual-duty weed preventer. It is compatible with lawns, flower beds, and vegetables.

Preen Weed Preventer work by blocking broadleaf weeds from emerging. This broadleaf prevents as plays a huge role in forming an unbreakable film on the ground, thus preventing thistle, nettles, and chickweed seeds from germinating. This film kills young thistle weeds instantly upon contact.

Conclusion

Having gone through our Best weed killer for thistle review and buyers guide, I hope that you have gained all the necessary information that will allow you to control thistles and their roost effectively from your yard.

Getting on the above herbicides will go a long way in keeping your yard, lawn, driveway, food plots, or pasture field free from thistles. Interestingly, all the product on the list is 100% eco-friendly and non-allergic hence safe to use around pets and household.