Remove wetter weed seeds


Chamberbitter (Phyllanthus urinaria) is also known as gripeweed, leafflower, or little mimosa. It is a warm-season, annual, broadleaf weed that emerges from warm soils beginning in early summer. It reproduces by seeds, which are found in the green, warty-like fruit attached to the underside of each branchlet.

Chamberbitter grows upright and has a well-developed taproot. The leaves are arranged in two rows on the branchlets and are thin and oblong, with smooth margins, resembling a mimosa seedling.

Management of chamberbitter is best achieved through the integrated use of mechanical, cultural, and chemical methods.

Mechanical Control

Mechanical weed control involves the physical removal of the weed from the soil. This is best accomplished by hand when weeds are young and small or in the seedling stage and easier if the soil is moist. Preventing the weed from reaching maturity and setting seeds also reduces future weed populations.

Cultural Control

Cultural weed control is the prevention of weeds through proper lawn management practices. A properly mowed turf that is not stressed by insects, diseases, drought, or nutrient imbalance is the best defense against weeds. For more information on watering, fertilizing, and mowing, see the following fact sheets: HGIC 1201, Fertilizing Lawns, HGIC 1205, Mowing Lawns, and HGIC 1207, Watering Lawns.

Within landscape beds, apply two to three inches of mulch in the spring to cover seeds from the previous season. Because chamberbitter seeds require light to germinate, this is especially effective.

Chemical Control in Lawns

Preemergence Herbicides: Because preemergence herbicides prevent seedlings from developing, they are an effective tool against annual weeds. However, they will not affect established weeds. Timing is critical. They must be applied prior to seed germination.

Atrazine is effective for preemergence control of chamberbitter in centipedegrass and in St. Augustinegrass lawns. Be careful not to apply on turf during the transition period from dormancy to active growth (spring green-up). Because chamberbitter tends to germinate in late spring and early summer (once the soil temperature reaches 70 °F), applications after grasses fully green up are effective. Target areas where chamberbitter was observed the previous season and be careful to not apply near the roots of desirable landscape plants. See Table 1 for examples of products.

Isoxaben is a preemergence herbicide that is effective for chamberbitter control in tall fescue, centipedegrass, St. Augustinegrass, bermudagrass, and zoysiagrass lawns. For home lawn use, it is purchased in a granular form, and the granules must be watered-in to allow the isoxaben to coat the soil surface for weed prevention. Make the first application in late spring and the second about 8 weeks later. See Table 1 for examples of products.

Isoxaben is also available as an additional active ingredient in one Bayer Advanced brand three-way herbicide. With this product, the postemergence, three-way, broadleaf weed control portion controls existing chamberbitter plants. The isoxaben portion will aid in preventing reinfestation of the area from seeds that may be present. To prevent new seeds from growing, the entire area to be protected must be sprayed. Wait 2 days after spray application and activate the isoxaben residual barrier by watering the lawn with ¼ to ½ inch of irrigation. Do not seed or overseed within 60 days after application. Do not apply isoxaben to a newly seeded lawn until it has been mowed 3 times. See Table 1 for an example of product.

Postemergence Herbicides: Postemergence herbicides are most effective when applied to young weeds. For postemergence control of chamberbitter in St. Augustinegrass and centipedegrass lawns, atrazine is recommended. It has both preemergence and postemergence properties. Make two applications spaced 30 days apart. Do not begin treatment with atrazine on these two turfgrasses until they are fully greened up in the spring.

On tall fescue, bermudagrass, and zoysiagrass lawns, repeat applications of three-way herbicides that contain 2,4-D, mecoprop (MCPP), and dicamba can be used to control chamberbitter. Apply these herbicides in late spring or early summer when the weeds are still young and space second application at 30 days later. These three-way herbicides may also be used on centipedegrass and St. Augustinegrass lawns at reduced rates and after the grasses have completely greened-up in the spring. Read the product labels for rates to mix and apply. See Table 1 for examples of products. For more information refer to HGIC 2310, Managing Weeds in Warm-Season Lawns.

Celsius WG Herbicide, which contains thiencarbazone, iodosulfuron, and dicamba, will control chamberbitter, especially if applied when the average daily temperatures are over 60° F. Apply when chamberbitter is actively growing and again 2 to 4 weeks later, if needed. The addition of a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides, will increase control.

See also  Strawberry cough seeds

Control in Landscape Beds

Postemergence Herbicides: The best choice for controlling existing chamberbitter in landscape beds is one of the many products containing glyphosate. Glyphosate will move through the plant and into the roots to kill the entire plant. Buy a 41% glyphosate concentrate and follow label directions for mixing a 2% solution to spray in a pump-up sprayer. See Table 1 for examples of products.

Glyphosate is a non-selective herbicide which can potentially damage any plant through contact with foliage or bark. Protect desirable plants from drift by not spraying in windy conditions, by keeping the spray nozzle close to the ground, and by using low pressure. Further protection is provided by attaching a plastic, cone shaped shield that surrounds the spray nozzle and confines the spray to the targeted plants. Shields can be made from bottomless two- liter drink bottles. Plants can also be shielded by covering with cardboard or something similar that is disposable.

When herbicides are applied to beds intended for future planting of ornamentals, care must be taken as various herbicides may injure the plants to be installed. For planned beds, glyphosate has far less soil activity (a few days) as compared with the three-way herbicides (a few weeks). Glyphosate is the safest choice for spray application in existing flower and shrub beds, so long as care is taken to prevent drift to non-target plants. Glyphosate applications are much less apt to move through the soil, be absorbed by roots, and injure existing woody ornamental shrubs.

Preemergence Herbicides: Isoxaben can be applied as a preemergence herbicide in landscape beds around certain well-established ornamental shrubs and trees to prevent chamberbitter from growing from seed. Products are best put below the mulch layer. Do not apply preemergence herbicides in beds where new plants will be installed, as plant root development may be inhibited. See Table 1 for examples of products.

Pesticide Safety

Always read the pesticide label and follow its directions exactly. Be sure to observe all precautions listed on the label. Mix pesticides at the rate recommended and never use more than the label says. Wear protective clothing or equipment as required by the label when mixing or applying pesticides. You may use the pesticide only on sites or crops listed on the label. Follow all label directions for pesticide storage and disposal.

Always heed the six most important words on the label: “Keep out of reach of children.”

Table 1. Examples of Herbicides for Chamberbitter Control in Turfgrass & Landscape Beds.

Roundup Original Concentrate

Roundup Pro Herbicide
Martin’s Eraser Systemic

Weed & Grass Killer
Hi-Yield Super Concentrate

Killzall Weed & Grass Killer

Bonide Kleenup Grass & Weed Killer Concentrate; & RTU 2

Eliminator Weed & Grass Killer Super Concentrate

Gordon’s Groundwork
Concentrate 50% Super Weed & Grass Killer

Knockout Weed & Grass Killer Super Concentrate

Monterey Remuda Full Strength 41% Glyphosate

Quick Kill Grass & Weed Killer

Southern States Grass & Weed Killer Concentrate II

Tiger Brand Quick Kill

Total Kill Pro Weed & Grass Killer Herbicide

Ultra Kill Weed & Grass Killer Concentrate

Pesticides are updated annually. Last updates were done on June 17, 2021 by Joey Williamson.

If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.


Chuck Burgess, Former HGIC Horticulture Extension Agent, Clemson University

This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. 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.

Seven pesky summer garden weeds and how to get rid of them

A wet spring and summer means lots of weeds, so which ones do you have and what is the best way to get rid of them?

See also  Bird seed weed

Hit them hard and hit them before they seed was the tip from weed agronomist Chris Butler.

“One of the [common weeds] has about 3,000 to 4,0000 seeds per plant,” Mr Butler told ABC Adelaide’s Weekends Talkback Gardening.

He said weeds generally fell into two categories — grassy or broadleaf — which determined how to treat them.

“Generally a broadleaf weed has a single stem and a tap root going into the ground.

“Grassy weeds have leaves that come up and a fibrous root system.”

Red root

“If you pulled this up carefully, that’s a good way to remove [red root],” Mr Butler said.

“It doesn’t set seed very early so you can pull it up effectively and put it in your mulch.”

Mr Butler said if the weed was removed when the soil was still moist, a long tap weed would be revealed.

Recommended herbicide: MCPA and dicamba or glyphosate.


“[Caltrop] comes up and flowers with a yellow flower,” Mr Butler said.

“They flower and seed very, very early.”

Mr Butler said if you have large weeds in the garden, they could be removed with a hand trowel as long as the long tap weed was also removed.

“Pick them up very carefully with the seeds and put them in the rubbish bin.”

Recommended herbicide: Broadleaf spray with MCPA and dicamba or glyphosate or a mixture of both.


“[Pigweed] is often used as food by some people, it has a fleshy stem and can be eaten,” Mr Butler said.

“A kettle full of boiling water will bring them down fairly well.”

Mr Butler said the weed sets seed very quickly, so it needed to be acted on quickly.

Recommended herbicide: Broadleaf spray with MCPA and dicamba or glyphosate or a mixture of both.

Goose foot

“[Goose foot] seeds prolifically and all of the little white stuff along the stem are seeds,” Mr Butler said.

“If you mulch heavily with wheaten straw or pea straw or bark chips you can generally control this.”

Recommended herbicide: MCPA and dicamba or bromoxynil and MCPA, or adding either to glyphosate.

Crab grass or summer grass

Crab grass is a prolific seeder, but can be removed by hand if done carefully. ( ABC Adelaide: Ashley Walsh )

“You can see from the photo [crab grass] is a prolific seeder,” Mr Butler said.

“It’s one that is not that hard to pull up if you get to it early.”

Recommended herbicide: Glyphosate.


“This is a massive problem in NSW. It’s glyphosate tolerant and takes a big dose to kill it here,” Mr Butler said.

“Get to it before it flowers, pull it up . and put it in the rubbish bin early.

“If you break it off it will tiller and put out lots and lots of side roots.”

Recommended herbicide: MCPA and dicamba.

Milk or sow thistle

With a natural waxy coating, milk or sow thistle is difficult to spray. ( ABC Adelaide: Ashley Walsh )

“[Milk thistle] is an absolute classic of a weed that manages its water loss through a waxy coating,” Mr Butler said.

“It is particularly difficult to get herbicide into and it is quite glyphosate tolerant in its own right.”

See also  How to know what strand os weed seeding

Recommended herbicide: MCPA and dicamba mixture, or glyphosate products with penetrant aids.

Herbicide use comes with a warning

Mr Butler warned herbicide mixtures should be made to directions on the containers.

Some chemicals mentioned may only be available for agricultural use or professional contractors.

“Don’t ever be heavy handed on these products because there is some soil activity associated with them.

“You only really need to spray the weed. You don’t need to spray the ground. It doesn’t need to be running off and puddling.”

Mr Butler said it was imperative to read the label and warnings and preferable to spray weeds first thing in the morning.

Posted 14 Feb 2017 14 Feb 2017 Tue 14 Feb 2017 at 11:51pm , updated 15 Feb 2017 15 Feb 2017 Wed 15 Feb 2017 at 12:49am

What Are Pre-Emergent Herbicides: Tips On Using Pre-Emergents

Even the most vigilant gardener will have a weed or two in their lawn. Herbicides are useful in the battle against annual, perennial, and biennial weeds, but you have to know when to use them and which ones are most effective against a particular weed problem.

Pre-emergence weed killers are used on established lawns as part of an annual effort to combat plant pests. What are pre-emergent herbicides? These chemical compositions are used before weeds take hold to kill off infant root systems and keep them from growing. Learn how pre-emergent herbicides work so you can decide if they are the right method for you.

What are Pre-Emergent Herbicides?

Pre-emergence weed killers are used before you see the weeds to prevent them from showing up in the garden or lawn. This doesn’t mean the chemicals interfere with germination but rather they stop the formation of new root cells in baby weed plants.

Without weeds, the seedlings cannot continue to feed and grow and they just die back. This whole process happens at the soil level under the blades and thatch of the grass so you don’t ever have to see the sprouted weeds. Timing, weather, and the type of weeds that are problematic in the garden will dictate the exact formula and application for using pre-emergents.

How Pre-Emergents Work

The chemicals in pre-emergent weed killers are not effective on vegetative buds that sprout from existing roots or rhizomes. They also cannot be used on a prepared grass seedbed because their root stunting action in young plants will also affect sprouting grass.

Established plants have nothing to fear, as their root system is already developed and the plant is hearty and healthy. Pre-emergent info indicates that it is the sensitive root tissue of newly germinated seedlings that is killed off, resulting in complete plant death.

Perennial weeds develop thick persistent adult roots that re-sprout in spring, which makes them difficult to control with a pre-emergent formula. Annual weeds are in two classes: winter and summer annuals. The timing of a pre-emergence weed killer for each must match the germination period for the variety of weed. Biennial weeds, like dandelions, are not controlled by a pre-emergent because they produce seed that germinates nearly year around.

Pre-Emergent Info for Applications

As with most plant chemicals, the weather and type of weeds will affect the application method. When using pre-emergents for winter annuals, apply in fall because that is when the seeds germinate. Summer annuals germinate in spring and that is the correct time to apply a pre-emergent. If you are unsure what type of weed is the most troublesome, it is a safe bet that a springtime application will control the majority of the pests.

Pre-emergent weed killers require water to activate them and carry the chemical down to the root systems of newly sprouted weeds. Never apply an herbicide spray when there is a wind to prevent injury to other plants. The ambient temperature must be above freezing and the soil should be workable. Consult the manufacturer’s label for the varieties of weeds the product is effective against and the method and timing of application.