University of Maryland Extension

Control Options

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Back to lawn weed identification

An Environmentally Responsible Approach to Weed Control

Before you rush out to buy an arsenal of chemicals, read and remember these tips. Also, it is perfectly acceptable to have a tolerable level of weeds in a home lawn - really! There has been much talk in the news lately about the plight of pollinators.  Did you know that common dandelion (Taraxacum officinale) and Dutch white clover (Trifolium repens) are two high quality forage plants for them, particularly early in the season when not much else is blooming? 

Glossary

 1) Terms for reading the product label

Active ingredient

Is the chemical contained in the herbicide that controls the target weeds. There can be more than one active ingredient. 

Chemical name (only one chemical name)

A complex technical description of the active ingredient contained in an herbicide.

chemical names
Common name (only one common name)A simpler version of the chemical name. See chemical name above.
Trade name

A name used by the manufacturer of an herbicide for marketing purposes.  Active ingredients can be sold under many trade names.
 

2) Mode of ActionSelective or Non-Selective - for lawn weeds a selective herbicide is preferred.

Contact herbicideAffects only the portion of the green plant tissue to which the herbicide was applied. They can ‘burn down’ the tops, but they cannot move within the plant’s vascular system and cannot kill the root, rhizomes or tubers of perennial plants. Vinegar and potassium salts of fatty acids are examples of organic contact herbicides. Effective against young, annual weeds, a poor choice for perennial weeds. 
Systemic herbicide

Are translocated or moved within the plant’s vascular system.  systemic herbicide
When applied in the late summer and fall to foliage the herbicide will translocate to the root system providing better control of perennial, difficult to control weeds. Can be selective or non-selective. May take weeks to kill the target weed. 
Nonselective herbicide

Kills or injures all plants, whether they are broadleaved or grassy, target and non-target that come in contact with the herbicide. Glyphosate, diquat, and vinegar are some examples. Glyphosate is typically used in preparation for total lawn renovation. These are usually not used on grass as they also will kill desirable turf grass.

Selective herbicide

Kills or damages certain plant species without seriously harming others. Often used to selectively kill broadleaf weeds growing in turf without injuring the grass. 2,4-D, Triclopyr, and Dicamba are some examples.

3) Timing of Application

Preemergent herbicide

Applied before the weeds begin to germinate.
preemergent herbicideTiming of application is important for effective control. Commonly used in the spring to control crabgrass.

Postemergent
herbicide

Applied directly to the foliage of weeds that have germinated. They can be selective or non-selective and work more effectively when the weeds are actively growing and not drought stressed.

    ~~~~~~~New trends in homeowner herbicides~~~~~~~

Manufacturers of lawn herbicides labeled for homeowner use are formulating more combination products. They contain a number of the active ingredients listed below under 'chemical options' and can control or suppress a large number of different weeds. There are combo products labeled to control both grassy and broadleaf weeds.  Some even contain both a postemergent and a preemergent for controlling existing weeds and preventing those that return from seed. Read and follow the label directions of the product you select. Look on the label for important information regarding the following: cautions, timing of application, weeds controlled or prevented, where to use, dilution rate (if a concentrate), watering, mowing and reseeding instructions.

Chemical Options

Chemical and trade names to look for on the label

For Grassy weeds

 
  • Preemergent - annual grassy weeds, like crabgrass and Japanese stilt grass
  • Apply prior to seed germination. For crabgrass this begins when soil temperatures are above 55° to 60°F for 7 to10 days (during and shortly after, forsythia bloom is a rough, but not consistently reliable, guide for application timing).
  • Water after application, according to label.
  • A second application may be possible (see label).
  • Consult label for specific waiting period between application and overseeding.
  • Only siduron (Tupersan) is labeled for application on newly seeded turf.

                       Examples

Common Name: Dithiopyr; Trade Name: Dimension (also some control on young crabgrass)


Common Name: Pendimethalin; Trade Name: Halts, others


Common Name: Prodiamine; Trade Name: Barricade


Common Name: Siduron; Trade Name: Tupersan (can be used when sowing grass seed)


Common Name: Benefin; Trade Name: Balan

Notesedges such as nutsedge are not grassy weeds (see below)

  • Postemergent - Selective
  • There are not many options for selective chemical control for perennial grass weeds like bermudagrass 
    (wire grass), Poa trivialis, or nimblewill.
  • Conventional treatment has been to spray the weeds with a non-selective herbicide that contains glyphosate at least twice a couple of weeks apart and reseeding the areas. This should be done in late summer into early fall. 

                   Examples

Common Name: Quinclorac; Trade Name: Drive

Common Name: Fenoxaprop-p-ethyl; Trade Name: Acclaim Extra, others

For Broadleaf weeds

**Products can contain one ingredient or a combination of active ingredients (combination herbicides are more effective on difficult to control weeds). They can contain a postemergent to control existing weeds and a preemergent to prevent them from developing or can be labeled for both broadleaf and grassy weeds (see ingredients above). **
Common Name: Isoxaben; Trade Name: Gallery

  • Postemergent - Selective
  • Apply when daily air temperature will be between 65° to 85°F. When temperature is too hot, herbicide will be more likely to volatilize and damage sensitive plants.
  • Do not apply when precipitation is expected within 24 hours.
  • Do not mow for a few days prior to or after application; and
  • Consult label for specific waiting period between application and overseeding

 

Common Name: These active ingredients are found in many herbicides. They can be the single ingredient or be combined to control a broader range of weeds. There are many trade names.

2,4-D
MCPP (mecoprop)
MCPA
Dicamba-be careful when using around tree and shrub roots.
Triclopyr
Carfentrazone

Sedges

Yellow nutsedge and kyllinga are the only significant lawn weeds in this category. 

                      Examples

Common Name: Halosulfuron; Trade Name: Sedgehammer and others

Common Name: Sulfentrazone

  • Vegetation killer - Non-Selective, kills both grass and weeds
Common Name: Glyphosate - Used for major lawn renovation projects to prepare the area before seeding.  

Organic and Less Toxic Controls

 

 
Products to control weeds with fewer chemicals are non-selective, contact herbicides. They will also kill your grass and are not effective on mature or perennial weeds that have a substantial root system.Active ingredients include: Acetic acid (vinegar), cinnamon oil, iron chelate, potassium salts of fatty acid, citric acid, and clove oil.
Corn gluten has been sold for many years as a preemergent herbicide. It can suppress annual weeds but not as effectively as traditional herbicides.

Corn gluten is a source of nitrogen. Applying it at the recommended amount to control weeds may exceed the amount of nitrogen allowable in Maryland per the (PDF) Fertilizer Use Act of 2011. Check the label to make sure. Some products are labeled as both an herbicide and a fertilizer. 

For more detailed information see our publications:

(PDF)HG 101 Guide to Controlling Weeds in Cool Season Turf

(PDF)TT-49 Broadleaf Weed Control in Established Lawns

(PDF)TT 46 - Perennial Grass Weeds and Their Control in Turf

(PDF)TT 43 - Herbicides for Crabgrass and Goosegrass Control in Turf

Link: National Pesticide Information Center Active Ingredient Fact Sheets

 

References to trade names do not constitute an endorsement or warranty by the University of Maryland.  No discrimination is intended against products not mentioned.

Home gardeners face many of the same insect pests and plant diseases as commercial growers, arborists, and landscapers. However, some pesticides recommended and labeled for professionals are not labeled or appropriate for gardeners. Pest management practices and recommendations on this website that are “brought to you by…” the Home and Garden Information Center or Grow It Eat It, are intended for the general public. Our goal is for all gardeners to learn and practice Integrated Pest Management (IPM) and select the least toxic solutions. If you have questions regarding any pesticide recommendation, contact us at Ask the Experts.

Tradenames mentioned in this publication are for product identification purposes only. No endorsement is intended.

Herbicides and active ingredients mentioned are registered in Maryland. Contact your local Extension Service for out-of-state recommendations. 

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