Weeds are basically unwanted plants or plants growing out of place. Proper identification and some understanding of how and why weeds are present in a lawn are important when selecting the best management tactics. All turf weeds can be grouped into one of three life cycles: annual, biennial, or perennial.
Annual: Produces seeds during one season only
Biennial: Produces seeds during two back-to-back seasons
Perennial: Produces seeds over many seasons
Knowing the types of weed previously present in an area also can help one to be better prepared and what control measures to employ in the future.
Weeds may appear in multiple categories, either broadleaf, grass, or Sedges/rushes.
Winter annual weeds in lawn in early spring. Photo credit: Larry Williams
Broadleaves, or dicotyledonous plants, have two cotyledons (seed leaves) when the weed seed germinates.
Appearance: Broad, flat leaves with net-like veins and usually have showy flowers.
Common types: Clover, ground ivy, dandelions, chickweed, plantain, henbit, beggarweed.
Grasses are monocotyledonous plants that have only one cotyledon, or seed leaf, present when seedlings emerge from the soil.
Appearance: Narrow leaves with parallel veins in their true leaves. Hollow rounded stems.
Common types: crabgrass, goosegrass, crowfoot grass, bull grass, annual bluegrass, alexander grass, cogon grass, torpedo grass, and smut grass.
Sedges/rushes. Both favor a moist habitat. Appearance: triangular-shaped, solid stems, while rush stems are round and solid.
Common types: yellow and purple nutsedge and, to some degree, globe, Texas, annual, and water sedge.
One of the first steps in managing weeds is to have a healthy dense lawn/ turf to provide shade that prevents seed germination. Having a healthy lawn depends on turf species selected – making sure you put the right plant and right place. Other factors that influence a heathy turf and a reduced amount of weeds include proper cultural control, fertilizing regularly, mowing at the appropriate height, watering deeply, reducing traffic, pest control, and sanitation. If you only have a few bothersome weeds in your lawn, you may be able to dig them up by hand—but if your lawn is overrun with weeds, you may need to start from scratch. If you decide to start from the beginning, you have a choice ahead of you. Do you want to lay down seed or sod? There are pros and cons to each.
Seed
Pros: Less expensive, more variety
Cons: Takes longer to germinate, can only lay at certain times of year depending on grass type
Sod
Pros: Instant grass, can lay any time of year, requires little maintenance
Cons: More costly, less variety in grass can mean less healthy lawn overall
To prepare the soil after either method, make sure you till it down to roughly 6 to 8 inches.
Supporting information for this article can be found in the UF/IFAS EDIS publications (Weed management for Florida lawns) https://edis.ifas.ufl.edu/publication/EP141 or contact your local Extension Office!
It’s the most asked question of Extension agents everywhere. “What is this weed and what herbicide should I buy to kill it?” The first part of that question is straightforward. Between personal field experience, formal plant identification training, and a team of weed science specialists to call on, Florida Extension Agents can get your weed accurately identified. The second part of the question is slightly more nuanced. Many weed problems can be avoided by following lawn and landscape Integrated Pest Management (IPM) practices, like not overwatering, mowing at the correct height, using mulch where you can, etc., but sometimes herbicides are required. For these situations, if you follow the “homeowners only need four post-emergent herbicides rule”, you’ll be ready for any weed challenge you face!*
Doveweed seedlings just emerged on July 9, 2021. Photo courtesy of Daniel Leonard.
The first weed scenario you should be prepared for is spot spraying weeds in landscape beds and around hardscapes like concrete pads, sidewalks, pools, driveways, etc. For this situation, you’ll turn to the backbone of the four herbicides rule and a staple in any weed management program, glyphosate. Glyphosate is the active ingredient (AI) in many non-selective products ranging from the infamous Roundup brand to cheaper generics like Killzall and Cornerstone. Glyphostate is extremely cost-efficient and very effective on a huge range of emerged weeds including grassy weeds, broadleaf weeds, and even sedges (also called nutsedge or “nutgrass”). Just be sure not to get any overspray on desirable plants or they’ll be seriously damaged!
The second situation we face occurs when “bad” grassy weeds invade landscape beds, shrubs, and vegetable gardens. These cases call for a grass-selective herbicide that you can spray right over the top of your broadleaf annuals, perennials, and shrubs to take out the unwanted grasses. In this case, there are two options at your disposal: sethoxydim (AI in many products like Fertilome Over the Top, Hi-Yield Grass Killer, Poast, etc.) and fluazifop (AI in the product Fusilade). Both products work well in removing weeds like crabgrass, bermudagrass, goosegrass, and others and can be safely applied over the top of many ornamentals.
Seeds from annuals like Chamberbitter easily get into mulch and turfgrass from surrounding areas. Photo by Beth Bolles, UF Extension Escambia County
From time to time, we need to treat a broadleaf weed like dollarweed, doveweed, chamberbitter, or any number of others, that have invaded our lawn grass. Some of these weeds are tougher than others, but almost all of them can be managed with the proper rates of 2,4-D, Dicamba, other similar products, or a combination of several of them. These active ingredients have been on the market for decades so there are many generic options at your disposal. However, if you have a truly tough broadleaf weed problem, the newer product Celsius WG from Bayer (a combo of Dicamba and two newer AIs), while a little pricey and only available online or at specialty chemical dealers, is well worth the expense and knocks out the most gnarly of lawn weeds.
Finally, there is a category of weeds that aren’t broadleaves and aren’t quite grasses either. These are the sedges. Commonly known around the Panhandle as “nutgrass”, sedges are a serious pest of lawns, particularly those that stay a little on the damp side, and vegetable gardens. Sedges, with their glossy leaves and distinctive flowers, stand out in lawns and gardens, are very unsightly in an otherwise well-maintained area, and can outcompete the desirable plants they invade. Fortunately, there are several AIs that work very well on sedges and are safe to use around turfgrass and many other plants. The most effective sedge herbicide AI for homeowners is halosulfuron-methyl (AI in Sedgehammer in lawns and Sandea and Profine in vegetables). Sedgehammer works very slowly (results can take up to a month) but is very safe in turfgrass and ornamentals and highly effective! If Sedgehammer and other halosulfuron products are difficult to obtain, Imazaquin is a slightly less effective but more common substitute. This AI can be found in the product Image Kills Nutsedge and is safe for use in turfgrass and most ornamental plantings.
The challenge of controlling the many types of weeds in your lawn, landscape, and vegetable garden seems daunting, but having just four basic classes of herbicides on hand can greatly simplify things! Whether you need to control a broadleaf, grass, or sedge weed problem, putting together a weed control toolbox containing a non-selective herbicide like glyphosate, a broadleaf selective like 2-4,D, a grass selective like sethoxydim, and a sedge selective like halosulfuron-methyl can allow you to handle most any weed you come across at home. For more information on controlling weeds in home landscapes and gardens or any other horticultural topic, contact your local UF/IFAS Extension office. Happy gardening!
*Most homeowners discover weed problems after the weeds are already up and growing, making post-emergent products necessary. Pre-emergent products have a place in weed management programs but are not the focus of this article.
Having a quality turf or plant sample is important to help us at UF IFAS Extension diagnosis a problem or identify a plant. Learn how to collect a sample of both turf and plant material if you will be bringing a sample to your local UF IFAS Extension County office.
The thistle has long been an enemy of ranchers, county roadside maintenance crews and homeowners. Often difficult to control, it causes both headaches for producers, in reduction of grazing for livestock as well as being an eyesore for gardening enthusiasts. There are nine different species of thistle in Florida. Most of these are closely related, therefore the control protocols are the same. Only one species is a perennial, and all others are biennial. A biennial plant grows from seed in one year and produces seed for the next.
Thistle that has begun to bolt. Photo Credit: Dr. Jason Ferrell, University of Florida/IFAS Agronomy Department-Weed Science.
It’s important to understand the biology of the thistle in regards of seeking control of this fast spreading weed. This plant will grow a taproot and a cluster of leaves in the first year. This is known as the rosette stage. In the second year, a stalk will appear from the center of the rosette. This is called “bolting”. A seed head will form once the bolting stage is complete. Amazingly, one thistle plant can amass 4,000 seeds. The plant faces its demise after releasing the seeds. The rosette growth stage is mostly during the winter months with bolting occurring from January to July. This is important to note when battling this persistent weed.
As for control, preventing the thistle from producing seed is the most important management measure. Otherwise, little can be done to stop the outbreak of the weed. For homeowners, manually removing the rosette and tap root by hand is effective with small stands. Be careful and wear protective coverings on your hands and arms. Keep in mind, the plant will come back if the tap root is not fully removed.
Other physical control methods, like mowing, have mixed results. This can be effective if mowing occurs after the bolting stage has occurred, but before the seed head forms. However, this is tricky, as thistle plants often do not bloom at the same time.
Thistles in the rosette stage are very susceptible to herbicides. Although, applying a herbicide after the seed head has formed has little effect on control. Herbicides containing 2,4-D are very effective for landscapes. Timing of application is critical. The key to controlling this weed is by scouting and identifying stands as early as possible.
If you’re a beekeeper, there is an upside to this weed. Delicious honey can be made from the thistle bloom.
Supporting information for this article can be found in the UF/IFAS EDIS Publication, “Thistle Control in Pastures” by Dr. Brent Sellers and Dr. Jason Ferrell.
UF/IFAS Extension is an Equal Opportunity Institution.
There are many problems that can plague a plant in our environment, from fungi that love the humidity in North Florida to insects that chew through leaves. One less common but interesting source of stress for plants comes from…other plants?
Most plants are content to gather energy from sunlight and nutrients from the soil in which they sink their roots. Some species, however, have taken up thievery as a lifestyle. Parasitic plants are those that take the nutrients they need to grow from other plants. Some rely completely on their hosts for nutrients, others are able to produce at least some of their own, while yet more can live on their own but steal nutrients if another plant is conveniently nearby. Furthermore, there are some plants and similar organisms that may seem to be parasitic, but actually do no harm.
Mistletoe is a common sight especially in the winter when trees’ leaves have dropped. It relies on its host for water and nutrients, though it can produce energy from photosynthesis. Being evergreen has led it its adoption as a symbol Christmastime, and it has historically been important to other cultures such as the Celtic druids. Too much mistletoe can weaken a tree, and removing it can help to reinvigorate one that is struggling. Physical pruning is often the only method available for its removal, and this can be difficult on a tree of any size.
Yellow tendrils and white flowers of dodder.
Dodder has a strange appearance, looking like someone threw a batch of angel-hair pasta all over a plant. There are ten different species of dodder in Florida and they may be found on a variety of host plants. This parasite is leafless and takes all it needs from its host, and cannot survive independently; though it germinates from the ground, it has no true roots. Controlling an infestation of dodder involves removing affected plants or at least pruning off the branches that are hosting the parasite. Herbicides will kill it, but they will also kill the host.
Ghost Pipe flowers
Ghost Pipe may be seen flowering from early summer through autumn, typically in woodland areas. It does not take its nutrients directly from a tree, but instead from mycorrhizal fungi. These helpful fungi attach to a tree and act like extra roots, assisting to absorb nutrients in return for energy from the plant. The ghost pipe helps itself to both nutrients and energy and does not bother to photosynthesize for itself, which gives it its stark white appearance.
Lichen may grow profusely on trees, but does not harm the plant.
There are also plenty of harmless plants out there, such as Spanish moss and resurrection fern, which grow on trees but are not parasitic. Lichens, while not plants, are similarly prolific on the bark of trees, but do no harm.
For help in identifying a potential parasitic plant, contact your local Extension office.
