Dogfennel Control: How to Get Rid of Dogfennel

This page is a general dogfennel control guide. You will get control of the dogfennel using the suggested products and methods. Follow this DIY guide and use the recommended products, and we guarantee 100% control of dogfennel.

Dogfennel is a tall summer annual or short-lived perennial weed that falls under Eupatorium capillifolium or dog fennel and thrives in poorly maintained south-eastern to west yards, pastures, and gardens. Depending on the conditions of the turf, this weed can grow to heights above 3 feet or reach full maturity as a short plant less than 6 inches. Despite the soft touch of the dogfennel leaves, this plant has a sour and musty odor when crushed.

This broadleaf weed prefers thin terrain containing moist to wet areas but does not do well in thick, established lawns. Once dogfennel has settled on your property, it releases numerous seeds, which will quickly suffocate other desired plants. This plant also contains a spreading rootstock that helps dogfennel to survive drought sites, such as Texas terrain.

The name dogfennel comes from the weeds used around the floor of dog kennels to ward off fleas and ticks. This worked because dogfennel contains an alkaloid toxin, pyrrolizidine, used in various insecticide products. If dogfennel is crushed, it produces a liquid secretion with the toxic alkaloid, which could cause liver damage. The liver will clog and begin to retain fluids if consumed in large quantities, which may cause death.

In this DIY guide, you will learn how to remove and prevent dogfennel on your property by following the steps and recommended products in this article. The directions and products suggested in this DIY guide were written by our lawn care experts and will show you how to properly remove dogfennel in a quick and cost-efficient manner.

Identification

Before a treatment program, you must determine if the weed on your property is dogfennel. Careless identification can lead you to use the wrong treatment method, which can waste time and money. Listed below are the identifying characteristics to know what dogfennel looks like:

• Dogfennel can be tall or short based on the space and nutrients available in its environment. Some reach 6 or more feet tall, while others will grow no more than 6 inches. Either size will be upright.
• Stems of young dogfennel will be soft and easily broken, but as the weed matures, it can become woody and tougher.
• The coloration of stems starts as green, then red as the fall season approaches.
• Leaves are thin, hairless, and have a feathery appearance. They are yellowish green and change to a subtle silver or red the closer fall approaches.
• Dogfennel is often confused with horseweed, mayweed, and pineapple weed. However, horseweed leaves are more divided and wider than dogfennel leaves. During the seedling growth, dogfennel is mistaken for mayweed or pineapple weed. Unfortunately, the only way to tell the difference is to crush the plant. When crushed, pineapple weed will have a pleasant aroma of pineapple, whereas mayweed or dogfennel odor is unpleasant. Seedling dogfennel also have hairy stems, unlike mayweed or pineapple weed.
• Flower blooms from September to November, when present they are small and range in color from white to pale green.

Use the description and image above to help you properly identify the dogfennel on your property. If unsure, then contact us with a photo of your weed, and we will identify it and suggest treatment options for you.

Inspection

Once you have confirmed that you are dealing with dogfennel, you can proceed to inspection. During this phase, you will locate areas where the dogfennel thrives and observe the conditions allowing it to thrive. This information will help you in knowing where to focus your herbicide application.

Where to Inspect

Dogfennel is often seen in pastures, areas of thin turf, parts of your yard prone to flooding or consistent moisture, and yards under poor maintenance. Common sites include, but are not limited to, home lawns, pastures, roadsides, and waste areas. 

Typically, dogfennel is dormant from January to March, but its seeds will sprout when temperatures reach 65 degrees Fahrenheit. As a summer annual weed, dogfennel can be found in parts of your yard exposed to full sunlight or partial shade.

What to Look For

When found on your property, dogfennel can easily be spotted due to its height or lacy fernlike leaves. This weed typically overcrowds other foliage in the area.

Treatment

Before carrying out a treatment plan, you will need to make sure you have the appropriate personal protective equipment (PPE) to handle any herbicide products or enter grassy areas.

Unlike other types of weeds, there is no specific time frame for applying herbicide products. To treat dogfennel, you will need to apply herbicide products containing either 2,4-D, glyphosate, bromoxynilor, clopyralid, dichlobenil, florasulam, fluroxypyr, metribuzin, sulfentrazone, triclopyr, or dicamba when the weed is 20 inches or smaller.

We recommend using Eraser 41% Glyphosphate as this product will treat a large variety of emerged broadleaf weeds like dogfennel on lawns, landscapes, and other terrains. Keep in mind this product is non-selective and will kill any vegetation it comes into contact with, so for this reason, you will need to do a spot application. 

Applications during drought should be avoided because dogfennel will become tougher to preserve water. Thus, herbicide material cannot move completely throughout the dogfennel's stem and roots, causing the weed not to receive the full effects of the used product.

Step 1: Measure Lawn and Mix Herbicide

Begin by calculating the square footage of the treatment area to determine how much product to use. To find this, you must measure the length and width of the treatment site in feet and then multiply them together (length X width = square footage). The formula for acreage is to take the square footage and divide it by one acre (square footage / 43,560 = acre).

Apply 2 1/2 oz. of Eraser 41% Glyphosate per gallon of water to treat an area as large as 300 sq. ft. You will need to use a handheld pump sprayer during mixing and application. 

To mix, pour half of the required amount of water, then fill with the measured amount of herbicide and add the remaining half of the water. Close the lid to the sprayer tank and shake to ensure an even mixture.

Step 2: Apply Herbicide in Mid-January to Mid-March

Adjust the nozzle on your sprayer to a fine spray pattern setting so it will spray a low-pressure mist on the dogfennel.

Spray the top and bottom of the dogfennel leaves until wet, but not to the point of run-off. We suggest placing a cardboard box around the weed during application to protect the desired foliage better. 

A suggested time to spray dogfennel is from mid-January to mid-March, as this is when dogfennel seedlings are beginning to emerge or germinate and when older or more established weeds are sometimes awakening from dormancy.

Check the weather forecast to ensure no rain or high-volume winds are predicted for 24 hours following application to avoid product drift or washing off the treated dogfennel.

Dogfennels with heights of 20 inches or more may need a following application in June as they may take longer to awake from dormancy and are harder to control. When less than 20 inches in height, dogfennel is much easier to eliminate and will take less application.

When applied properly, affected weeds will turn yellow and begin to die. A follow-up application may be necessary if signs of recovery are observed, especially if the plant’s taproot is still alive. A reapplication with Eraser 41% Glyphosate may be made after 4 weeks.

Prevention

After you have treated the dogfennel on your property, you will need to implement some preventative measures to ensure this weed does not return. Implement the following preventative measures to keep the invasive weed from re-establishing.

• Hand-pull seedings with a gloved hand in areas where mowing can not be performed, such as garden beds.
• Dogfennel does not do well in thick, established turf, so practices such as fertilization are recommended. We recommend Solutions 15-5-10 Weed and Feed Fertilizer with Trimec, which acts as a fertilizer and eliminates germinating weeds like dogfennel in turf. Use 3.2 to 4.0 lbs. of product per 1,000 sq. ft.). You will need an inch of water to activate the granules after application. 
• Help strengthen your grass by mowing at the proper height of 3 to 4 inches in turfgrass. This will help stimulate growth, which will cause grass roots to choke out dogfennel seedlings before they can emerge.
• Improve air circulation in your soil by raking or dethatching your lawn. Circulation in your soil helps nutrients, water, and grass roots spread more easily.
• Once a week, water your lawn deeply with an inch of irrigation in the early mornings. Apply the water all at once in the morning so it has time to seep into the ground without evaporating in the sun.

Key Takeaways

What is Dogfennel?

• Dogfennel is a perennial summer weed that falls under the Asteraceae family and can grow tall or short in thin, distressed lawns, pastures, gardens, and grassy areas.

How to Get Rid of Dogfennel

• Our recommendation to remove dogfennel is to use Eraser 41% Glyphosate to eliminate this weed.

Preventing Dogfennel

• By maintaining a regular lawn care schedule and promoting a lush, green, nutrient-rich turf, dogfennel will not be able to establish.