Oxalis | Gardening in the Panhandle

Gardening in the Panhandle LIVE Program Summary: Weeds – February 4, 2021

by Mark Tancig | Feb 11, 2021

Gardeners worldwide and throughout time have bemoaned weeds. In Florida, we get to enjoy weeds all year long! Our February Gardening in the Panhandle (GIP) Live episode focused on weeds and weed control. Many homeowners are interested in ways to control weeds and UF/IFAS Extension and your local extension agents are here to help. The following is a summary of the topics we discussed and links for more research-based information on weeds.

What is a Weed?

Many folks come to the extension office holding a plant and ask, “Is this a weed”? Well, whether it is a weed or not is up to the individual, as the only definition for a weed is “a plant out of place”. Bermudagrass and Oxalis are good examples of plants that some try to grow while others try to kill. One person’s weed is another’s wildflower! However, to be clear, plants classified as invasive by UF/IFAS and governmental entities are officially weeds. There are resources to help identify several common plants that are generally considered weeds by most homeowners and landscapers.

Weed ID Links

Florida Weeds: https://sfyl.ifas.ufl.edu/lawn-and-garden/florida-weeds/
Edible Weeds: https://content.ces.ncsu.edu/extension-gardener-handbook/6-weeds
Identifying Weeds: Virginia Tech: https://weedid.cals.vt.edu/ and NC State: https://www.turffiles.ncsu.edu/weeds-in-turf/
Weeds of Southern Turfgrass: http://ifasbooks.ifas.ufl.edu/p-150-weeds-of-southern-turfgrasses.aspx

Common, and aggravating, weeds.

How to Prevent Weeds?

There are some general gardening practices that can help prevent weeds so there is less of a need to control them. A lawn that is healthy is less likely to be invaded by weeds and the use of mulch can greatly reduce weed growth in planting beds. Other practices, like the placement of weed fabrics/cloths are less effective and/or less practical in many garden situations.

Weed Prevention Links

Mulching Guidelines: https://ag.umass.edu/home-lawn-garden/fact-sheets/mulching-weed-management-in-urban-landscape
FYN Handbook – Principle #s 1, 2, 3, 4, 6: https://ffl.ifas.ufl.edu/materials/FYN_Handbook_2015_web.pdf
Consider Landscape Fabric Carefully: http://blogs.ifas.ufl.edu/escambiaco/2016/08/12/consider-landscape-fabric-carefully-2/

How to Control Weeds?

Once you know and/or decide that what you have is a weed and that it needs to be dealt with, then you have to consider your control options. Prevention, as mentioned above, is key but sometimes you may need to use other methods of control, such as physical, mechanical, and/or chemical means. With chemical weed control, it is important to always read and follow the product label.

Weed Control Links

Weed Management Guide for Florida Lawns: https://edis.ifas.ufl.edu/ep141
Weed Control in Planting Beds: https://edis.ifas.ufl.edu/ep523
Non-Chemical Weed Control: https://edis.ifas.ufl.edu/hs1170
Summer Annual Weed Control Timeline: https://sfyl.ifas.ufl.edu/media/sfylifasufledu/escambia/horticulture/Summer-Annual-Lawn-Weed-Control-Timeline.pdf
Winter Annual Weed Control Timeline: https://sfyl.ifas.ufl.edu/media/sfylifasufledu/escambia/horticulture/Winter-Annual-Lawn-Weed-Control-Timeline.pdf
Florida Homeowner Herbicide Guide: https://edis.ifas.ufl.edu/pdffiles/EP/EP57500.pdf
National Pesticide Information Center: http://npic.orst.edu/
Glyphosate Alternatives: https://edis.ifas.ufl.edu/ep580
Pesticide Use Around Pets: http://npic.orst.edu/health/pets.html

General dates of common annual weed emergence. Credit: Dr. Ramon Leon, UF/IFAS.

Specific Weed Recommendations

When managing pests, proper identification is key to effective control. Because some weeds are annuals, and present either during the cool or warm season, and others are perennials, proper weed identification can provide a more detailed control strategy. Use the weed ID links above and the document links below for more precise, and effective, weed management.

Species-Specific Control Links

Dandelion Control: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7469.html
Dollarweed Biology and Management: http://edis.ifas.ufl.edu/ep389
Doveweed Control: https://edis.ifas.ufl.edu/pdffiles/AG/AG39500.pdf
Johnsongrass ID and Control: https://edis.ifas.ufl.edu/ag372
Oxalis Control: https://edis.ifas.ufl.edu/ep514
Torpedograss Control: https://plants.ifas.ufl.edu/plant-directory/panicum-repens/

If you need additional assistance with weed control, please contact your local county extension office. Please tune in for future GIP LIVE episodes for more research-based information on gardening topics.

Summer Annual Weeds Thriving in Panhandle Lawns

by Ray Bodrey | Sep 6, 2018

Figure 1: Chamberbitter, a common annual weed.
Credit: Mary Salinas, UF/IFAS Extension Santa Rosa County.

With daily rainfall occurring regularly, coupled with humid temperatures, summer annual weeds have had a mighty boost in growth. Chamberbitter, Florida pusley, sedge and oxalis are just some examples of the many weeds that are exploding across our landscape.

Chamberbitter (Phyllanthus urinaria) is found as north as Illinois and as west as Texas, but thrives in lower southeastern states. It’s a headache for homeowners as well as pasture managers. The foliage resembles that of the mimosa tree (Albizia julibrissin) and can be confused with the native mimosa groundcover, known as powderpuff mimosa (Mimosa strigillosa). This plant grows upright and develops a long taproot. Wart-like seeds can be found on the underside of the branch.

Florida Pusley (Richardia scabra L.) also known as Florida snow or Mexican clover, has recently blanketed landscapes in the Panhandle with white flowers. It’s a persistent weed that moves quickly.

Sedges and sedge-like plants (Cyperus ssp.), known as kyllinga, are species that emerge in late spring and thrive in summer months in warm, moist climates. Excessive irrigation or areas with poor drainage create a very hospitable environment for these weeds. Sedges are annual grass-like plants have an elaborate flower-bearing stems. Yellow and purple nutsedge are the most common species. Kyllingas have smaller leaves and are less vertical. Sedges and kyllingas are fast spreading, and reproduce through seed and rhizomes, or underground tubers.

Oxalis or yellow woodsorrel (Oxalis stricta) have heart-shaped lobes and have a bright yellow flower. Oxalis reproduces by seed and have a narrow “okra-like” seed pod.

Figure 1: (L to R) Chamberbitter, Pusley, Sedge, Kyllinga & Oxalis.

Credit: Stephen H. Brown, UF/IFAS Extension Lee County

What about control? Some cultural control methods are hand removal and mowing frequently to offset the life cycle, but these practices alone will most likely not solve the problem. There are many broad spectrum herbicides that can be used to control these weeds with good results, but you must be persistent. Some are season long applied products. However, most effective products need to be applied in cooler temps than we have now. Consecutive days of temperatures of less than 90 degrees would be optimal. Applying the chemical otherwise will most likely harm the turfgrass. Be aware, some productions will injure or kill centipede and St. Augustine, but are safe to use on other turfgrasses like bermuda, bahia and zoysia. Be sure to read the label and follow the directions and precautions.

Another option is non-selective herbicides, like glyphosate, which can be used in thick patches or for spot treatment. When using a selective herbicide, remember to protect turfgrass and other plants from spray drift or any contact, especially regarding ornamental plants and trees.

Contact your local county extension office for more information.

Supporting information for this article is from the following online publications:

Clemson Cooperative Extension publication: “Chamberbitter”, Bulletin HCIC 2314: http://www.clemson.edu/extension/hgic/pests/pdf/hgic2314.pdf

UT Institute of Agriculture document, “Nutsedge and Kyllinga Species” by Mathew T. Elmore, James T. Brosnan and Gregory K. Breeden: http://www.tennesseeturfgrassweeds.org/Lists/Fact%20Sheets/Attachments/23/W260updated2015.pdf

UF/IFAS EDIS publications: “Yellow Woodsorrel (Oxalis) Biology and Management in Turf” by J. Bryan Unruh, Ramon G. Leon, and Darcy E. P. Telenko: http://edis.ifas.ufl.edu/pdffiles/EP/EP38500.pdf

“Weed Management Guide for Florida Lawns” by J. Bryan Unruh, Ramon G. Leon, Barry J. Brecke, and Laurie E. Trenholm: http://edis.ifas.ufl.edu/pdffiles/EP/EP14100.pdf

UF/IFAS Extension is an Equal Opportunity Institution.