Description

Chamberbitter (Phyllanthus urinaria L.), also known as gripeweed, little mimosa or leafflower, is a warm-season, annual, broadleaf weed with an erect growth habit. Chamberbitter is an invasive weed that can invade lawns, garden beds and agricultural fields. It germinates in the late spring or early summer after the soil has warmed considerably (approximately 75 F). Chamberbitter is tough to eradicate with a well-developed taproot and is a prolific seed producer. Once established, chamberbitter is considered tough to control, and complete eradication can be difficult to achieve.

Identification

Chamberbitter has ½ to ¾ inch long, thin, green, oblong leaves with smooth margins. Its leaves are compound and arranged in two rows on the branchlets (Figure 1). Chamberbitter flowers are inconspicuous (Figure 2), producing green fruit attached to the underside of branches (Figure 3). It reproduces through prolific seed production. In certain instances, chamberbitter can be confused with powderpuff mimosa (Figure 4). For more information on chamberbitter identification and characterization, visit the U.S. Department of Agriculture Plants Database.

Figure 1 (left). Thin, green, oblong leaves with smooth margins. Figure 2 (right). Inconspicuous flowers.

Figure 3 (left). Green fruit attached to underside of branches. Figure 4. Chamberbitter, middle, can be confused with powderpuff mimosa, right.

Cultural control practices

The best way to prevent or reduce weed encroachment is to maintain a healthy lawn through proper fertilization, soil pH management and regular mowing. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass, allowing it to better compete with weeds. Below are the recommended mowing heights and nitrogen fertility rates recommended for each turfgrass species. In addition to these lawn care practices, manual removal of weeds may also be necessary.

Chemical control practices

In addition to cultural practices, herbicide applications may be required to achieve effective weed control. For hard-to-control weeds like chamberbitter, multiple herbicide applications and higher rates may be necessary to achieve satisfactory control. Ensure your lawn has fully greened up before spraying atrazine or a combination herbicide product containing 2,4-D, MCPP and dicamba to St. Augustinegrass and centipedegrass. Remember, postemergence herbicides are less effective when controlling established mature weeds.

When applying any type of herbicide, you must follow the manufacturer’s labeled directions. For more information regarding pesticides for turfgrass, please reference the Louisiana Suggested Chemical Weed Control Guide.

*2,4-D is a common herbicide used to control broadleaf weeds. However, centipedegrass and St. Augustinegrass are sensitive to 2,4-D, and its use can potentially damage or even kill these grasses. It is generally not recommended to use 2,4-D on centipedegrass or St. Augustinegrass unless the product label specifically states it is safe for use on this type of grass and the product is applied according to the label instructions.

Sources

Murphy, T. R., & Colvin, D. L. (1992). Weeds of Southern turfgrasses: Golf courses, lawns, roadsides, recreational areas, commercial sod. University of Florida, Cooperative Extension Service, Institute of Food and Agricultural Sciences.

Patton, A. J., & Elmore, M. (2023). Turfgrass Weed Control for Professionals. Purdue University Extension

For information regarding weed identification and control options, please contact your local LSU AgCenter Extension Parish Office.

Download here: Louisiana Home Lawn Series: Chamberbitter (P3624-IIII)