What You Need to Know About Gripeweed AKA Chamberbitter

By: Alice Marty, Mobile County Master Gardener | www.MobileCountyMasterGardeners.org

Pre-emergent seems to not affect it! Common herbicides do not seem to faze it! The experienced gardener will find it in their flowerbeds after thinking that their weed war was won. Most gardeners do not know it by name. Or perhaps you have given it another name, although maybe not as polite as chamberbitter, gripeweed, shatter stone, stonebreaker, or leaf flower to name a few. The world of horticulture knows it as Phyllanthus urinaria. It is an herb species in the family Phyllanthaceae and has been added to the noxious weed list in Alabama.

Chamberbitter is an increasingly common invasive weed that has been spreading heavily across regions of the country with more tropical climates. It is a broadleaf weed that sprouts in warm season grasses annually during the early summer. It is believed that the weed originated in tropical Asia, but it has become a major lawn pest across the southeastern United States from Virginia to Texas. Preferring to grow in excessively high temperatures or areas with long periods of drought, chamberbitter enjoys our zone 8b lawns. As it is drought tolerant and produces so many seeds, it is quite difficult to control on landscapes. It grows quickly and has an extensive taproot which makes this weed particularly difficult to completely remove without the help of chemicals. Hand pulling is a largely useless option because they will just pop up again before long.

The plant resembles the leaves of a mimosa tree and goes to seed when it is only about an inch tall. The seeds are little balls that develop on the underside of the leaves. The seeds explode and scatter giving hundreds of new weeds their start. Even very few plants can produce vast new crops this year and next.

After you have identified the weed as chamberbitter, it is important to know that chemicals may be most effective at certain times of the year. You can waste time and money if you try to chemically treat a weed at the wrong time of the year. The pre-emergent you used in March will not bother the seeds it had laid for growing this year. It is a summer weed and begins showing itself in May and June, after you have used the post emergent herbicide for the spring weeds in April.

Before using chemicals, know your grass type. Not all chemicals are safe to spray on all types of grass. Many property owners have two or even three types of grasses in a lawn that weeds invade. Make sure the chemical can be sprayed on those grass types.

Practice healthy turf management techniques. Make sure your grass is healthy before applying any weed control chemicals. A healthy lawn incorporates proper mowing heights for grass, having sharp mower blades, not cutting more than 1/3 of the leaf blade off at a time, and making sure proper fertilizer practices are being followed. You also want to avoid treating during periods of drought and seasonal transition periods such as spring green-up and fall dormancy.

Do your neighbors, friends, or family members borrow your lawn equipment? If so, make sure the equipment is clean before using to avoid invading your lawn with weeds or seeds from another yard. Lawn disease can also be transmitted this way.

Before using any herbicide product, make sure you first have on the proper PPE for safety (gloves, glasses, mask). It is especially important for your own safety as well as your family and pets.

Be sure to read the entire label. Knowing what care will be needed if a chemical accident occurs can hasten relief and affect outcome. Avoid using lawn chemicals of any kind when temperatures are high. Your lawn is already heat-stressed, adding chemicals will be adding stress, a mistake you will regret.

Glyphosate (Roundup) will kill chamberbitter, but you must be careful to keep the chemical off nearby foliage. In a lawn, broadleaf weedkiller (Weed-B-Gon, Weed Stop, etc.) applied twice, seven days apart should be effective.

If you cannot identify your weed or have other lawn questions: contact your County Extension Master Gardener Help Line. Home Grounds and Garden information line 1-866-855-1909.

Home Lawn Maintenance - Alabama Cooperative Extension System (aces.edu)

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