Thistle is an invasive, noxious, persistent, and nonnative herb belonging to the sunflowers family. It is both an annual and a biennial herb. There exists 2,500+ species of thistle globally. They are dominantly found in the Southwest of the United States of America, which encompasses New Mexico, Arizona, Western Oklahoma, and Texas.
These temperate regions offer optimum conditions for the growth, development and reproduction of herbs. Thistles’ persistence is attributed to its rapid production, propagation of seeds, and ability to sprout from fragments of active rhizomes. This calls for effective control measures utilizing chemical Herbicides to effectively control it. Read the entire article to learn details.
This write-up entails:
- The top 5 herbicides for thistle.
- How to identify and manage thistle herbs
- Approaches to managing herbs
| Parameter | Monterey Thistledown | Compare-N-Save Grass and Weed Killer | Roundup Weed and Grass Killer | Southern Ag Amine 24-D Weed Killer | Ortho Weed-B-Gon |
| Usage, ft per pack | 15,000 | 25,000 | 25,500 | 18,500 | 5,000 |
| Visible Results, Days | 3 – 4 | 2 – 4 | 2 – 4 | 3 -5 | 1 |
| Concentrated Element (name and %) | Clopyralid 40% | Glyphosate 41% | 50.2% Glyphosate | 2,4-D-Dichlorophenoxyacetic acid 46.3% | 2,4-D-Dimethyl salt 6.42%, Quinclorac 2.13%, Dicamba dimethyl salt 0.6% |
| Application Rate | 3 lbs/gallon | 3 – 5 tablespoons in 1 gallon of water | 2.5 ounces/gallon | 3 tablespoons in 5 gallons of water for 1000 sq ft | 2.5 ounces / gallon of water for every 400 sq ft |
| Month to Use | Between March to May | March to May | April | Between April and June | From March to May |
Monterey Thistledown – Best Herbicide for Canada Thistle
This is a proven remedy for broadleaf weeds, including Canadian, Musk, Star thistle, Knapweed, and Oxalis. Its active component clopyralid permits its safe usage on sods, sods, and cropless areas.
This concentrate formulation gives ultimate control against the persistent thistle herbs during their active growth. Regrettably, this herbicide can’t be sprayed on ornamentals or crop areas. It causes harm or injury if it falls on exposed skin.
Pros
- Kills multiple broadleaf herbs
- Safe on greenswards
Cons
- Not usable crops
Compare-N-Save Grass and Weed Killer – Eliminates All Unwanted Herbs
It has the ability to annihilate existing herbs and halt the development of fresh herbs.It is supplied in miscible formulation hence easing its usage. It lasts up to 4 months in the soil. It is the preferred herbicide for herbs management on domestic and commercial lawns..
Its first action composition presents results in a little under three days with total elimination of herbs guaranteed a fortnight. Has high adhesion to the foliage making it resistant to wash off beyond 120 minutes after application and increases absorption into the plant roots. Application should be done when thermal conditions are beyond 60℉.
Pros
- Eliminates herbs
- Friendly to edible vegetation
- Resistant to wash off
Cons
- Destroys all plants
Roundup Weed and Grass Killer – Offers Economic Value for Vast Application
Contains Glyphosate which permeates to extirpate the herb from the roots. Damaged roots reduce the spread and colonization rate of sod by the herbs. It gives excellent monetary value for protracted applications given its extensive coverage hence its high economic value.
This herbicide resists wash-off in half an hour post-application, ensuring maximum contact time with the herb. Timely killing action ensures the plant commences wilting after 76 hours and requires 2-3 weeks to take out all the herbs from your lawn completely. This product causes skin irritation during contact.
Pros
- High economic value
- Compatible with blossom and trees
- Vast coverage
Cons
- Requires special equipment to dispense
- Destroys every vegetation
Southern Ag Amine 24-D Weed Killer – Best Eclectic Broadleaf Weed Killer
This formulation has lethal action against specific broadleaf herbs like Thistle and Velvetleaf. It is however tolerable to sods and selectively eliminates herbs. It possesses the power to destroy both existing and developing herbs to constrain dense herbs buildup.
Follow product’s directives while spraying to realize the stipulated coverage. Best applied in sunny weather with no precipitation. One to four pints can be sprayed over an acre of land. Employ targeted spraying with low pressure. Southern Ag is harmful if ingested.
Pros
- Eliminates unwanted herbs only
- Destroys present and anticipated herbs
Cons
- Noxious to bare skin
Ortho Weed-B-Gon – Best Herbicide for Broadleaf Weeds
Ortho has 200+ weeds on its kill list including Clover, Dandelion and Thistles. With 3 active ingredients, it offers excellent selectivity to herbs while sparing the sod. It gives immediate outcome in 24 hours after usance.
Ultimate care and requisite protection are necessary amid application as it is harmful to humans and animals. Also, it’s usage is restricted to a limited sod species – consult the product’s label for compatibility information. Optimum usage temperature is from 85℉ and beyond. It becomes waterproof 60 minutes after spraying.
Pros
- Eliminates 200+ herbs
- Destroys herbs faster
- Destroys roots
Cons
- Hazardous to humans and pests
- Not compatible with all sods
Buyer’s Guide
How to Destroy Thistle Herbs?
This includes the use of Natural, organic, or chemical herbicides. However, due to herbs’ persistent nature, chemical herbicides like Ortho Weed-B-Gon that kill the entire plant including the roots have proven more effective of the three.
How to Identify Thistles?
Purple blossom and spiny leaves with alternate sided grooves is the characteristic appearance of thistle herbs although they may differ slightly in appearance for the different species. Below is a step-wise guide for accurate identification.
How to Destroy Thistles Using Vinegar?
Obtain 20% horticultural vinegar and dilute. Accurately target spray each herb until it is dripping with the formulation. The herb will eventually wilt within 1 week. However, the advisable method with timely outcome is the usage of herbicides like Roundup Weed and Grass Killer.
Can Thistle Reappear Within the Same Season?
Yes, if the chemical power of the herbicide has faded. There is almost a guarantee that they will visit again after the chemical wears off. This is because the roots stay active and sprout again despite prior wilting.
How Long Does the Herbicide Effect Last?
The outcome appears averagely before the elapse of 3 days; however, for significant destruction it takes close to 2 weeks of active action against the herbs like Southern Ag Amine 24-D Weed Killer. Some herbicides take less or more duration to utilize their kill power exhaustively
FAQ
Their active growth season is Spring or Fall.
Consider uprooting, burning or slashing, grazing, or seeding sod.
Wet conditions with temperatures beyond 65℉.
Conclusion
Thistle herbs are stubborn and persistent. They often reappear after the implementation of management protocols. Only the tested and proven scientific formulations have proven successful in completely exterminating this herb. They work by killing the entire herb to the roots therefore giving it no chance of bouncing back.
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