Summer is here and so is the onslaught of summer weeds. A weed that is problematic for many gardeners is Chamberbitter (Phyllanthus niruri). It is also referred to as “Little Mimosa” because its leaf resembles the Mimosa leaf. Another name for it is, “Gripeweed,” maybe because folks “gripe” about how hard it is to eliminate. A summer annual, Chamberbitter dies out in the winter and then reappears in early summer about mid-June. Preemergent herbicides applied in the spring provide good control of most summer annual weeds, but not Chamberbitter. Chamberbitter is not easily controlled by most herbicides. So how can we control the “Gripeweed?”
How it grows
Knowing a little bit about Chamberbitter’s life cycle can help you to make cultural and mechanical control methods more effective. Chamberbitter is a summer annual, meaning that it grows from seed each year when temperatures get warm and then dies after frost, root and all. It is commonly found in turfgrasses and ornamentals. It reproduces by seeds, which can arise in the axil of every leaf. Each seedpod contains several seeds (usually three). These seeds pods, on the underside of the leaves are unique, and help identify the plant. Chamberbitter can be 2 to 36 inches tall. Seeds tend to germinate in warm temperatures (above 70°F), and tend to be seen in mid to late summer in Paulding County.
Cultural control
“Prevention is the best medicine” applies to reducing many problems in the lawn and garden. Proper fertilizer applications (per soil test report recommendations), regular watering, controlling disease and insects, proper mowing height are critical to keeping lawns healthy and better able to compete against weeds. Ensuring your lawn is healthy is the best way to control Chamberbitter in lawns.
Mulching is effective in controlling growth of Chamberbitter in your gardens. In addition to needing warm weather to germinate, it also requires light. Spread 2-4 inches mulch to help reduce seed germination. A personal recommendation is to apply three layers of newspaper around plants and shrubs before mulching to increase light reduction. Note that if mulching after Chamberbitter has sprouted, pull the weed before mulching for better results.
Mechanical control
Along with good mulching practices, weeding is one of the most effective ways to control Chamberbitter in the garden. Chamberbitter is easy to pull, especially when it is young. It does have a taproot, which makes it more difficult to pull when it is more mature, therefore moisten the soil before weeding. Examine the back of the leaf for presence of seeds before you begin weeding – they are easy to see. If seeds are present, pull it by the stalk, holding it close to the ground and place it into a bucket or onto cardboard, or plastic, as you do not want the seeds to fall onto the ground for next year. Discard the weeds and do not place them in a compost pile.
If you notice chamberbitter in your lawn or garden, get started on control practices early. If this weed becomes well established it gets harder to control!
The author of this article, John Shipley, is a Paulding County Master Gardener Extension Volunteer. As representatives of the University of Georgia Cooperative Extension, Master Gardener Extension Volunteers are trained experts, who answer questions about home horticulture, sustainable landscaping, and environmentally friendly gardening practices using unbiased, research-based information from the University of Georgia. For more information on gardening, contact Paulding County UGA Extension at 770-443-7616 or check us out online at www.ugaextension.org/paulding.
