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How Long Does it Take for Quinclorac to Work & Kill Weeds?

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Written By: Mark Marino

a Massachusetts Core Applicator License holder and owner/operator of Lawn Phix,

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Quinclorac is an effective selective herbicide to control any crabgrass problems. This weed killer is popular among many homeowners and most lawn care professionals as it kills a broad spectrum of grassy weeds and broadleaf weeds. It can also be mixed with other 2-way and 3-way herbicides that contain 2,4-D, dicamba, MCPP, or triclopyr. When trying to eradicate weeds, particularly crabgrass, you’ll probably wonder how long it takes for quinclorac to kill weeds…

How Long Does it Take for Quinclorac to Work?

Quinclorac takes 10-14 days to work and kill crabgrass and other weeds. Evidence of quinclorac working on the plant can be seen within the first three days after application. Signs of dying include the wilting and discoloration of the weeds (turning brown, yellow, purple). Results may vary depending on the conditions, growth stages of the weeds, and applied mix rates.

A second application of quinclorac can be applied again after 14-21 days.

How to Kill Crabgrass with Quinclorac

Crabgrass will germinate in the early spring when soil temperatures reach 55 degrees and warmer.

Mix your spray tank with half the amount of water, followed by your quinclorac, methylated seed oil, and then the remaining water. Spray evenly over the entire lawn where crabgrass is present. Avoid the treated area for 1-2 hours or until the herbicide has completely dried before re-entering.

We have had great success Drive XLR8 , which contains 18.92% quinclorac as the active ingredient. Mix 1.45 ounces of Drive XLR8 and 0.55 ounces of methylated seed oil per gallon of water. It is labeled safe for most lawns and grass types.

Is Quinclorac safe for warm-season grasses?

The product label directions of quinclorac state that it is highly tolerant on Buffalograss, Bermudagrass (common), and Zoysiagrass; moderate tolerance on paspalum, bentgrass, and bermudagrass (hybrid); and susceptible on bahiagrass, carpetgrass, centipede grass, and St. Augustine grass.

Is Quinclorac safe for cool-season grasses?

Quinclorac is very safe for almost every cool-season grass type: turf type tall fescue (TTTF), perennial ryegrass, and Kentucky bluegrass. It should not be applied to fine fescue – including hard and red fescue – unless it is part of a seed blend.

How often can you apply Quinclorac?

Time sequential applications of quinclorac are 14-21 days apart. Do not apply more than 1.45 ounces of quinclorac (Drive XLR8) per 1,000 square feet in a single application or more than 2.9 ounces per 1,000 square feet per year.

Can you use Quinclorac on Bermuda grass?

Quinclorac is safe to apply on Bermuda grass as directed on the product labels.

How long does Quinclorac take to dry?

The time to dry is dependent on the outside temps and conditions. Under warm, dry conditions, Quinclorac will dry within an hour when applied according to the product label directions.

How long after Quinclorac can I mow?

You need to wait at least two days to mow your lawn before or after applying quinclorac products.

Will Quinclorac kill mature crabgrass?

Yes, quinclorac will kill larger and more mature crabgrass (five-tiller stage) when applied correctly and used with methylated seed oil.

What temperature do you spray Quinclorac?

The best temperature and conditions to spray quinclorac are when weeds like crabgrass are actively growing. This is between 65-80 degrees Fahrenheit. The potential for burning increases when temperatures are warmer (85 degrees or hotter).

Is Quinclorac a pre-emergent?

No, quinclorac is not a pre-emergent herbicide. It is a post-emergent herbicide – or weed killer – and will not prevent weeds from germinating or emerging. It is one of the best selective herbicides for killing crabgrass and broadleaf weeds.

Should I mow before applying Quinclorac?

You can mow your lawn two days before spraying quinclorac crabgrass killer to best control weeds.

Is Quinclorac a selective herbicide?

Yes, quinclorac is a selective herbicide to kill grassy weeds like crabgrass, foxtail, and torpedograss, and broadleaf weeds like black medic, clover, and dandelions.

Can Quinclorac be mixed with other herbicides?

Yes, quinclorac can be combined with other selective herbicides containing active ingredients 2,4-d, triclopyr, or dicamba. We mix with On Deck or Speedzone to tackle a broad spectrum of unwanted weeds.

Is it better to spray for weeds before or after mowing?

It is best to mow your own two days before spraying weeds. You should also mulch your clippings for three consecutive mowings after spraying quinclorac.

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Author's Note: this piece has been updated for accuracy since its first publication on
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Author: Mark Marino
My name is Mark Marino, and I am the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier lawn care services and advice. I am a fully licensed and insured lawn care applicator in Massachusetts, specializing in comprehensive turf nutrition, weed control, and lawn pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

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