Monday, April 28, 2014

Weed of the month for March 2014 is Common Chickweed

Common Chickweed  

Biology: Common chickweed (Stellaria media) is a winter annual broadleaf weed. It forms dense, prostrate patches in turfgrass throughout North America, though it can grow much taller when it’s not mowed. Common chickweed germinates from seed in late summer or early fall. However, germination timings can vary throughout the year if conditions are shady, and moist enough. Its prostrate growth habit and capabilities to withstand low mowing practices make common chickweed a widely distributed turfgrass weed in all regions of the United States.

Identification: Common chickweed is predominantly a winter annual broadleaf weed that can be identified by its prostrate growth habit and leaf shape. Common chickweed leaves are located opposite each other on stems that may be hairy on older portions and smooth on newer growth. Additionally, leaves are light green, smooth, and oval- to egg-shaped that come to a point at the apex. Leaves located on the upper portions of the stems have no petioles (leaf stems) while leaves located lower on the stems have long, sparsely-hairy petioles. Common chickweed produces small clusters of white flowers with five daisy-like petals in early spring. Flower petals have a deep centered lobe that makes it appear as though there are ten petals. Common chickweed can often be mistaken for mouse-ear chickweed; however, mouse-ear chickweed leaves are more oblong in shape and are densely covered in soft hairs. 

Light green leaves with tiny point at the apex

Leaves may often look more succulent than herbaceous

Daisy-like flowers with 5 petals. Petals have deep lobes so it appears there are 10 petals

Prostrate growth habit via laterally spreading branches

Dense, mat-like growth

Presence may indicate moist, poorly drained, or compacted soils

Cultural control: Proper turf maintenance such as adequate mowing height, fertilization, and irrigation will help to develop a dense, aggressive turf capable of out-competing invading weeds. Common chickweed is also an indicator weed, meaning its presence might indicate underlying management issues that are allowing the weed to dominate spaces meant for turf. For example, it thrives in compacted soils that are consistently moist or poorly drained. Its presence might indicate that the soil should be cultivated (aeration) and irrigation practices should be adjusted to reduce excess moisture in the soil. Common chickweed also thrives in shady conditions; thus, efforts to reduce shade if possible, such as pruning tree branches, may also help turf out compete common chickweed. Hand-pulling common chickweed when populations are small may also be an effective cultural weed management tool.

Biological control: None known for specific use in common chickweed. There are some organic postemergence herbicides available for turf weed control such as pelorgonic acid (Scythe), acetic acid (5% or greater solutions), and medium-length fatty acids (Eugenol); however, these products do not differentiate between the target weed and the desired turf (non-selective). As a result, these products are often used as spot treatments for weed control in parking lots, along fence rows, and in other bare-ground areas.

Other organic products that contain iron HEDTA (FeHEDTA), may be used to manage common chickweed; however, their ability to control common chickweed has not been effectively researched.

Chemical control: Control options for common chickweed include both pre- and postemergence management strategies. Preemergence herbicides such as Gallery 75 (isoxaben), Pendulum (pendimethalin), Barricade (prodiamine), and Dimension (dithiopyr) are available for use in home lawns; however, it is important that they are applied prior to common chickweed germination in autumn.

Postemergence control can be achieved with repeat applications of two or three-way mixtures of 2,4-D, dicamba, MCPP, or MCPA in cool-season turf.  In warm-season grasses, Manor (metsulfuron), Katana (flazasulfuron), or Celsius (thiencarbazone + iodosuluforn + dicamba) can control common chickweed when applied in combination with a non-ionic surfactant (0.25% v/v).

Most of these herbicides require supplemental applications for adequate control especially in spring when common chickweed plants are larger.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate


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