How to Identify and Spot-Treat Round Leaved Weeds

The Problem with Round Leaved Weeds in Turfgrass

Homeowners frequently group all broadleaf weeds together, assuming a single off-the-shelf herbicide will eliminate them. This approach fails spectacularly with round leaved weeds. Species like Creeping Charlie (Ground Ivy), Dollarweed, and Common Mallow share a similar circular leaf profile but possess entirely different reproductive strategies, root structures, and chemical resistances. Applying a standard 2,4-D product to Creeping Charlie, for example, will only burn the top growth while the stolons continue to spread underground.

Successful eradication requires precise identification followed by targeted spot-treatments using specific active ingredients, correct surfactant ratios, and optimal seasonal timing. According to the University of Minnesota Extension, misidentification and improper herbicide selection are the primary reasons homeowners struggle with these specific weeds year after year.

Diagnostic Flowchart: Which Round Leaved Weed is in Your Lawn?

Before purchasing any herbicide, examine the weed's stem attachment and leaf margin. Use this decision tree to identify your specific invader:

• Stem attaches to the center of the leaf (peltate) like an umbrella: You have Dollarweed (Hydrocotyle umbellata). Leaves are perfectly round, glossy, and lack scalloped edges.
• Stem attaches to the edge, leaves have scalloped margins, emits a minty odor when crushed: You have Creeping Charlie (Glechoma hederacea). Also known as Ground Ivy, it forms dense mats in shaded, moist areas.
• Stem attaches to the edge, leaves are deeply lobed (geranium-like) with a velvety texture: You have Common Mallow (Malva neglecta). Often found in compacted soils and neglected lawn edges.

Targeted Spot-Treatment Protocols by Species

1. Creeping Charlie (Ground Ivy)

Creeping Charlie is notoriously difficult to kill because standard 2,4-D herbicides are largely ineffective against it. You must use a product containing Triclopyr. Triclopyr mimics plant growth hormones specifically in a way that disrupts the vascular system of woody and semi-woody broadleaves, translocating down into the creeping stolons.

2. Dollarweed

Dollarweed is an indicator weed. Its presence almost always signals over-irrigation, poor drainage, or compacted soil. While chemical control works, the NC State University TurfFiles database notes that dollarweed will aggressively return unless moisture levels are corrected. Furthermore, dollarweed leaves have a waxy, hydrophobic cuticle that causes liquid herbicides to bead up and roll off.

3. Common Mallow

Common Mallow develops a deep, resilient taproot. If you attempt to pull it by hand, the root snaps below the soil line, and the weed regenerates within weeks. Spot-treatment requires a fast-acting burn agent combined with a systemic translocator to ensure the taproot is destroyed.

Herbicide Comparison Matrix

Critical Application Rules and Edge Cases

Even with the correct herbicide, environmental factors and application errors can cause spot-treatments to fail. Adhere to these professional parameters to ensure efficacy and protect your turfgrass:

Temperature and Volatilization Limits

Never apply ester-based formulations of 2,4-D or Triclopyr when daytime temperatures exceed 85°F (29°C). At high temperatures, these chemicals undergo volatilization—they turn into a gas and drift onto nearby desirable broadleaf plants, shrubs, or trees, causing severe twisting and cupping damage. If you must treat in late spring or summer, apply in the early morning when temperatures are below 80°F and the wind is completely calm (under 3 mph).

Mowing and Hydration Schedules

Do not mow your lawn for 48 hours before or 48 hours after spot-treating. The weed needs maximum leaf surface area to absorb the chemical, and the herbicide needs 48 hours to translocate out of the leaf and into the stolons or taproots. Additionally, do not apply herbicides to drought-stressed weeds. If the lawn is dry, water it deeply 24 hours before application. Weeds shut down their vascular systems during droughts to conserve water, which prevents the systemic herbicide from moving to the roots.

"According to Purdue University Turf Extension, the most common failure mode in broadleaf weed control is applying herbicides to weeds that are too large or mature. Spot-treat round leaved weeds when they are young and actively growing for a 90%+ kill rate, rather than waiting until they have established massive root networks."

Frequently Asked Questions

Will horticultural vinegar kill round leaved weeds?

No. Horticultural vinegar (20% to 30% acetic acid) is a non-selective contact burn herbicide. It will destroy the top growth of Creeping Charlie and Mallow within hours, but it does not translocate. The stolons and taproots will survive and push up new growth within 10 to 14 days. Furthermore, high-concentration acetic acid drastically lowers soil pH and can harm surrounding turfgrass roots. Stick to synthetic systemic herbicides for permanent eradication.

Why did my Creeping Charlie turn yellow but not die?

This is the classic symptom of using a standard 2,4-D lawn weed killer that lacks Triclopyr. The 2,4-D causes the leaves to curl, yellow, and die back, but the active ingredient cannot effectively penetrate the plant's specific defense mechanisms to reach the stolon network. Switch to a Triclopyr-based product and apply in the fall for a complete kill.

Can I use a weed and feed granular product instead of spot-treating?

Granular weed and feed products are highly inefficient for established round leaved weeds. Granules must stick to moist, broad leaves to be absorbed, which is difficult to achieve uniformly. You will end up applying excessive synthetic nitrogen and herbicide to your entire lawn just to target a few patches of weeds, increasing the risk of turf burn and environmental runoff. Liquid spot-treatment using a 1-gallon pump sprayer is vastly superior, more cost-effective, and environmentally responsible.