Test Your Knowledge - November

Common chickweed
Common chickweed
Karan A. Rawlins, University of Georgia, Bugwood.org

Yes! This is common chickweed.

Chickweeds frequently infest home lawns, ornamental beds and vegetable gardens, and generally appear in the fall. These cool weather weeds will grow rapidly during the fall, winter and spring months, and then produce an abundance of flowers and seeds from spring through early summer.

Common chickweed (Stellaria media) is a winter annual that grows as a flat, mat-forming plant, which is covered in white, five-petaled flowers during the spring. These five petals are deeply notched and appear as ten. The plant thrives in moist, shady areas, especially in soils that are high in nitrogen, where it creates very dense mats of shoots.  Seed production is its primary means of spread, and each plant may produce between 600 and 15,000 seeds.

Young chickweed
Young, spreading common chickweed as seen in the fall.
Photo by John D. Byrd, Mississippi State University, Bugwood.org

Mouse ear chickweeds (Cerastium vulgatum and C. glomeratum) are similar looking chickweeds that are winter annuals or perennials. The leaves of mouse ear chickweeds are very pubescent or hairy, versus the leaves of common chickweed that are smooth. The stems of these spreading, mouse ear chickweeds will root readily upon soil contact, and seed production by these species is also high. Seeds of all chickweeds may remain viable in the soil for several years, resulting in a constant battle to maintain control.

Mouse ear chickweed
Mouse ear chickweed with hairy leaves.
Joseph M. DiTomaso, University of California - Davis, Bugwood.org

To help prevent seed germination in the fall, keep the lawn healthy and thick by testing the soil, and applying the recommended amount and type of fertilizer and lime at the correct time of year. Irrigate the lawn properly, as excessively frequent irrigation keeps the soil continually moist and conducive to chickweed seed germination and weed growth.

Chickweeds may be hand pulled or dug from lawns and flower beds. Plant beds may be mulched to prevent further seed germination. Lawns may be treated in the early fall with a preemergence herbicide to prevent seed germination, or can be sprayed with a postemergence herbicide after weed appearance. Younger chickweed plants are more easily controlled in the fall by postemergence herbicides than are older plants in the spring. Since chickweeds flower and produce seed in the spring, it is better to treat the lawn in the fall before flower production begins. See the following tables for lists of preemergence and postemergence herbicides.

Table 1. Efficacy Ratings of Preemergence Herbicides for Control of Chickweed Species.
Chickweed
Species
Preemergence Herbicides
Atrazine Benefin Dithiopyr Isoxaben Oryzalin Pendimethalin Prodiamine
E = Excellent control (90 to 100%)
G = Good control (80 to 89%)
Common
Chickweed
E G G E G G-E E
Mouse Ear
Chickweed
-- E -- G -- G G

 

Table 2. Turfgrass Tolerance to Preemergence Herbicides.
Preemergence
Herbicide
Turfgrass Species
Bermudagrass Centipedegrass St. Augustinegrass Tall Fescue Zoysiagrass
D = For use on dormant turfgrass.
NR = Not registered for use on this turfgrass species.
S = Safe for use; follow label directions.
Atrazine D S S NR NR
Benefin S S S S S
Dithiopyr S S S S S
Isoxaben S S S S S
Oryzalin S S S NR S
Pendimethalin S S S S S
Prodiamine S S S S S

 

Table 3. Efficacy Ratings of Postemergence Herbicides for Control of Chickweed Species.
Chickweed
Species
Postemergence Herbicides
Atrazine Dicamba Imazaquin MCPP Metsulfuron
E = Excellent control (90 to 100%)
G = Good control (80 to 89%)
Common
Chickweed
E E E G E
Mouse Ear
Chickweed
G E G G E

 

Table 4. Turfgrass Tolerance to Postemergence Herbicides.
Postemergence
Herbicide
Turfgrass Species
Bermudagrass Centipedegrass St. Augustinegrass Tall Fescue Zoysiagrass
D = For use on dormant turfgrass.
NR = Not registered for use on this turfgrass species.
I = Intermediate tolerance; use lower rate
S = Safe for use; follow label directions.
Atrazine D S S NR NR
Dicamba S I I S S
Imazaquin S S S NR S
MCPP S I I S S
Metsulfuron S NR S NR S

 

Table 5. Examples of Brands of Preemergence and Postemergence Herbicides.
Preemergence
Herbicide
Brands & Specific Products
Notes: Many 3-way postemergence herbicides contain both dicamba and MCPP (mecoprop). There are several different Image products and Ortho Weed-B-Gon products. Always check the label for the correct active ingredients, as well as that it is labeled for use on the specific turfgrass.

* Recommended for use by professional turfgrass managers.
Atrazine Image for St. Augustinegrass & Centipedegrass with Atrazine
Hi Yield Atrazine Weed Killer
Southern Ag Atrazine St. Augustine Weed Killer
Benefin Green Light Amaze Granules (benefin & oryzalin)
Hi Yield Crabgrass Control (benefin & trifluralin)
Dithiopyr Green Light Crabgrass Preventer with Dimension
Hi Yield Ornamental Weed & Grass Stopper
Isoxaben Green Light Portrait Granules
Oryzalin Green Light Amaze Granules (benefin & oryzalin)
Pendimethalin Scotts Halts Crabgrass Preventer
Prodiamine Barracade (several formulations)*
Postemergence
Herbicides
Brands & Specific Products
Atrazine Image for St. Augustinegrass & Centipedegrass with Atrazine
Hi Yield Atrazine Weed Killer
Southern Ag Atrazine St. Augustine Weed Killer
Dicamba & MCPP Bayer Advanced Lawn Southern Weed Killer for Lawns (also with 2,4-D)
Ortho Weed-B-Gon for Southern Lawns (also with 2,4-D)
Spectracide Weed Stop Weed Killer for Lawn (also with 2,4-D
Imazaquin Image Nutsedge Killer
Metsulfuron Manor Selective Herbicide*

Joey Williamson, Ph.D.
Home & Garden Information Center

Page maintained by: Home & Garden Information Center

This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.