Poisonous Plant? Take a Closer Look, but Not Too Close!

Poisonous Plant? Take a Closer Look, but Not Too Close!

During summer and fall, a lot of us spend hours trekking through forested areas and pasture lands, either for work, if we are lucky, or by simply enjoying the great outdoors. Unfortunately, there are not-so-nice life forms that also enjoy this time of year, like poisonous plants. There is a long, long list of enemies when discussing poisonous plants. However, there are a few more common, native plants, like poison ivy, poison oak, poison sumac and poisonwood that we should be fully aware of in our surroundings, along with their friendly mistaken counterparts. This article will help to distinguish poison ivy from Virginia creeper.

Figure 1: Poison Ivy on Left / Virginia Creeper on Right in Fall Colors. Credit: Sydney Park Brown, UF/IFAS.

Poison Ivy (Toxicodendron radicans) grows in just about any location imaginable. Poison Ivy is probably the most common and most irritating (mentally & physically) poisonous plant one will come in contact with. This is a woody shrub that can reach 6 feet in height or grows like a vine up to 150 feet tall on trees. As a vine, it is often found on fences and trees. The leaf forms three leaflets, which can be 2-6 inches in length and may have smooth edges or can be toothed. Leaves are shiny with a tint of red most of the year. Leaves will turn purple before dropping in the fall. Remember the old saying when it comes to identifying poison ivy, “leaflets three, let it be.”

Virginia Creeper (Parthenocissus quinquefolia) is commonly mistaken for poison ivy. It is a climbing vine as well with similar growth patterns. However, there are some distinguishing traits, as Virginia Creeper has five leaflets, instead of three. Virginia Creeper also has blue-black berries along with tiny, sticky segments that are used to attach to surfaces. During the fall, Virginia Creeper leaves turn red before dropping.

There are some important precautions about poison ivy that we should remember when out and about. Warmer months correspond with the increased sapping stage of poisons plants, which means the allergic reaction from contact is both more likely, and possibly more severe. The four native poisonous plants mentioned earlier all contain urushiol. This is a plant oil that causes a severe skin rash when contact is made. People have different sensitivity levels to exposure. Symptoms appear within a couple of days and the itching and burning of the skin can last weeks. Over the counter products with the active ingredient dient bentoquatam can help prevent or reduce the reaction. This product must be applied before contact is made. If exposed, as soon as possible clean area with warm, soapy water and rinse with cool water. Contaminated clothing should be washed separately from other laundry. Severe reactions may need professional medical treatment.

Poison ivy, poison oak, poison sumac, and poisonwood.  Credit: Cook (2012); Larry Korhnak, UF/IFAS

Contact your local county extension office for more information on poisonous plants in your area.  Supporting information for this article can be found in the UF/IFAS EDIS publications: “Identification of Poison Ivy, Poison Oak, Poison Sumac and Posionwood,” by Sydney Park Brown.


Are Endophytes and Mycotoxins in Florida Forages Affecting Cattle Performance?

Are Endophytes and Mycotoxins in Florida Forages Affecting Cattle Performance?

Stroma stage of Myriogenospora atramentosa on Argentine bahiagrass pasture in North Florida. Photo credit: Ko-Hsuan Chen, UF/IFAS


Ann Blount, Sunny Liao, Ko-Hsuan Chen, Marcello Wallau, Doug Mayo, Brittney Justesen and Clay Cooper

Stroma stage of Myriogenospora atramentosa on Pensacola bahiagrass leaf blade. Photo credit: Ko-Hsuan Chen, UF/IFAS

Endophytes are naturally occurring organisms that often live in symbiosis internally in many of our forage species. Basically, endophytes are good for plants to associate with. They are typically a bacteria or fungus that lives within a plant for all or part of its life-cycle. These organisms occur in most plant species and can boost the plant’s tolerance to abiotic stresses, such as drought, and assist the plant to acquire nutrients, enhance growth, and resist insects and diseases that might harm the plant. They can also aid the plant by reducing overgrazing by wildlife or livestock. In return for aiding the host plant with survival, the endophyte receives nutrients from the host plant, such as carbon or nitrogen.

Recently, these endophytes have been suspected as a possible cause of animal health issues on Florida cattle ranches. This, however, is not a new phenomenon. The most commonly known pasture endophyte relationship occurs in fescue. Cattlemen who rely on fescue-based pastures know what the mycotoxin (ergovaline) from the endophyte fungus Neotyphodium coenophialum in fescue does to cattle. There is a long history of studies to reduce the associated problems of fescue-related mycotoxin toxicity in livestock with better pasture management and fescue variety breeding.

Similar to this phenomena in fescue, endophytic fungi also infect sub-tropical grasses, and in some cases, these endophytes may also produce mycotoxins. Researchers have documented mycotoxin issues in southern grass pastures, but they have not typically been so apparent or serious as fescue toxicosis.

Stroma stage of Balansia epichloe on Smutgrass leaf blade. Photo credit: Ko-Hsuan Chen, UF/IFAS

Why the sudden interest in this topic now? Probably because producers have become better livestock stewards and have the annual performance records that document small changes in animal behavior and variation in performance from year to year.

If you research old publications, you will find a number of studies that document the occurrence of these endophytes in many sub-tropical grasses. Old published research articles, dating back to the 1950s and again in the early 1980s, implicate animal health concerns with livestock grazing bermudagrass, bahiagrass, smutgrass and broomsedge.

Over the past three years, several ranchers in Florida have reported livestock problems related to early abortion in cattle, poor bull performance, and heat stress, and have implicated the forages. These performance issues may have been due to a wide range of other factors.  Isolating the forages as the cause is hard to confirm. Therefore, a research grant was secured from the Florida Cattlemen’s Association to allow UF/IFAS researchers to do a two-year, statewide study in 13 locations.

A team of 12 University of Florida state specialists and 12 county agents have teamed up with the 13 Florida cattle ranches to do on-farm sampling of Bermudagrass, bahiagrass, and limpograss to determine the level of endophyte toxicity in the state. Four of the 13 locations are in North Florida.  Forage samples will be collected six times per year in 2018 and 2019.  The goal of this statewide study is to identify the endophytes that are present at different points in the year, so that future studies can focus on how these specific endophytes affect animal performance.

So far, the research team has confirmed the identification of several fungal families living endophytically in pasture grasses, such as Fusarium spp., Balansia spp. and Myriogenospora spp. They have also found seasonal mycotoxin activity in these forages. From recently processed forage samples researchers have identified and quantified the presence of zearalenone, ZEAR-4-sulfate Q1, alternariol, ergine and 15-AcetylDON, as well as several other mycotoxins of potential concern to animal health.

It is still much too early to know if the mycotoxin concentrations from these initial forage plant samples are impacting cattle health or performance.  Once this study is complete, future research will focus on the specific endophytes of concern to identify potential management options to recommend to cattle producers in the region.

Doug Mayo, Jackson County Extension sampling Tifton 85 Bermudagrass in July 2018 in Jackson County. Photo credit: Ann Blount, UF/IFAS

The UF/IFAS Forage Endophyte team will provide updates as they identify specific endophytes and mycotoxins in Florida forages.  They will also be studying their seasonal occurrence and what environmental conditions are favorable for production of mycotoxins.

Stroma stage of Myriogenospora atramentosa on Argentine bahiagrass pasture in Jackson County. Photo credit: Doug Mayo


Weed of the Week:  Perilla Mint

Weed of the Week: Perilla Mint

Photo Credit: Tennessee Vascular Plants Eugene Wofford

Perilla Mint is a toxic ornamental that has escaped from landscapes in the Southern U.S. and is now an established pasture weed. As a summer annual it grows in shaded areas up to a height of 2 feet tall. It is often identified by its purple shading on the undersides of the leaves. All parts of the plant are toxic to livestock, with symptoms including labored breathing and death. Late April to early June is the ideal time to scout your pastures for Perilla Mint.

For help identifying weeds or developing a control plan for your operation, please contact your county extension agent. 

For more information on this topic please use the links for the following  publications:

UT Extension Perilla Mint

Scout Pastures for Toxic Perilla Mint

Spring is a Good Time to Scout Pastures for Toxic Weeds


Prolific Pokeweed Now Emerging

Prolific Pokeweed Now Emerging

Warm weather and ample soil moisture have encouraged common pokeweed to get an early start in 2018.

Common pokeweed (Phytolacca americana) is a perennial weed native of North American frequently found in pastures as well as fence-rows, row crop fields, and wooded areas.  As winter moves to spring, this plant is emerging from its winter dormancy. The recent warm weather has accelerated the regrowth in North Florida.

Pokeweed is toxic to livestock.  All parts of the plant contain saponins, oxalates, and the alkaloid toxin phytolacine. The roots and seeds of this species contain the highest concentrations of these compounds.

Once common pokeweed becomes established, it regrows each year from a large, fleshy taproot. The crown of the root is where the plant is regenerated and can be as large as five and a half inches in diameter at the soil surface within two growing seasons.

Pokeweed usually has a red trunk like stem, which becomes hollow as the plant matures later in the year. Leaves become quite large as the plant grows to its full potential and are the basis for poke salad.

When in bloom the individual flowers appear green to white and are typically missing petals. Fruits are green when immature and turn a deep purple to black at maturity which is the basis for one alternate name for this species, inkberry.

Each fruit contains about nine small, hard-shelled seeds. Pokeweed can produce over 48,000 seeds per plant annually.

These seed may remain viable in the soil for over four decades (40 years) under the right conditions. When exposed to the right environmental conditions the seeds sprout and the process is repeated.

While not a suitable selection for people or livestock, birds eat the fruits without much evidence of harm and are usually the means for seed dispersal. Roosting sites along fence rows and under utility lines frequently show signs of seed deposits.

In addition to feed for cardinals, mocking birds, cedar waxwings, and other birds, the pokeweed is a host to a variety of insects. Some are beneficial and others are not.  A number of caterpillars utilize this weed to sustain their larval stage of development. Unfortunately, some other less desirable insects use the local weed as well.

Pokeweed can act as reservoirs of various viruses transmitted by insects and are destructive to agronomic as well as ornamental plants. Whiteflies and aphids are the main culprits, but other insect species can contribute to the disease issue.

Control of common pokeweed can be a bit tricky because of its strong tap root and large crown.  Single plants can be removed by digging out the crown and most of its tap root.  For more extensive populations, the herbicide active ingredients glyphosate, 2,4-D, or dicamba can severely injure or kill the plant.

To learn more about pokeweed and its control, please read this UF/IFAS publication Common Pokeweed, or contact the nearest UF/IFAS County Extension Office.


Weed of the Week: Bracken Fern

Weed of the Week: Bracken Fern

Photo Credit: Chris Evans, River to River CWMA, Bugwood.org

Bracken Fern is a common perennial fern that is found across the United States. Its ability to grow well is both dry and moist soils, as well as along tree lines, in wooded areas, and around buildings, make it a well-adapted species. While all parts of the fern are toxic, the rhizomes are most toxic, with horses and swine being most susceptible to the toxicity and ruminants being more tolerant. Toxicity is caused by an induced B1 deficiency, however, livestock rarely consume large quantities of bracken fern, unless forage availability is limited.


For help identifying weeds and developing a control plan for your operation, please contact your county extension agent. 

For more information on this topic please see the following UF/IFAS Publication: Bracken Fern Control in Pastures


Weed of the Week: Coffee Senna

Weed of the Week: Coffee Senna

Coffee senna is a troublesome pasture weed that is toxic to livestock. Photo credit: Doug Mayo

Coffee Senna is not only an issue for livestock producers, as seeds are toxic when consumed, it also causes issues for cotton and peanut farmers in the southern states. The scientific name Senna occidentalis comes from Arabic and Latin roots, with Senna meaning “these plants” and occidentalis meaning “western,” in reference to its origin. While closely related to Sicklepod, Coffee Senna does not respond the same to many of the herbicides used for Sicklepod control in row crop production, making it challenging to control.


For help to identify weeds or to develop a control plan for your operation, please contact your county extension agent. 

For more information on this topic please see the following UF/IFAS Publication:

Weed Management in Pastures and Rangeland—2017