A stand of purple flowers called “False Dragon-Heads (Physostegia spp.) growing along the St. Marks River. They are behind a stand of pickerelweed (Pontederia cordata) that has not yet bloomed. Photo: Judy Biss
This is the time of year when gardens burst forth with lush green growth and colorful flowers. With a little planning and management, your backyard pond can also put on the same show each year and fight unwanted pond weeds at the same time!
Fish and farm ponds are abundant in the Florida panhandle. Most are two acres or less and are used for producing catfish, bass, and bream; for recreation and wildlife viewing; for fishing and swimming; and for irrigation and livestock watering. Ponds play an important role in various aspects of agricultural production and rural life, and for that reason, maintaining their ecological health is critical to their many uses.
Managing aquatic plants is one important component of pond ownership. If you are a pond owner, you have probably seen and read many articles related to controlling and removing aquatic weeds. Just as in terrestrial gardens, there are a number of non-native (and sometimes native) plants that can become quite weedy and problematic in and around your pond. Hydrilla, water hyacinth, torpedograss, Chinese tallow, alligator weed, and the tiny water spangles (common Salvinia) are just a few examples that plague our waterways and shorelines. But, controlling and removing weeds is only part of the bigger picture of pond management. Planting native wetland plants is another ecologically important and aesthetically enriching management tool as well.
By establishing beds of healthy native plants, you are also fighting against weedy non-native invasive plants through competition for space. Some other benefits of native aquatic plants are they act as a barrier, filtering fertilizers such as nitrogen and phosphorus from runoff, and they help control erosion. Also, because native plants are adapted to our local environments, they are generally easy to grow, and most require little or no extra water or fertilizer.
Below are a few guidelines to follow if you are considering the use of native aquatic plants in your pond.
Know Your Plants:
Depending on the type, aquatic plants generally grow in three forms. Emerged, like maidencane or bulrush, submerged like coontail and southern naiad, and floating, like the tiny free floating duckweed, and spatterdock and fragrant water lily which are rooted with floating leaves and flowers at the water’s surface. There are many good UF/IFAS publications and online resources for aquatic plant identification. Some are listed at the end of this article.
Plan Ahead:
Some questions to ask are, what is the primary use of your pond? Is it wildlife viewing, swimming, fishing, irrigation, etc.? The answers to these questions will help you determine how much of your pond and shoreline will be planted, and what types of plants to use. For example, if you use your pond for fishing and irrigation, you should leave some areas of the shore unplanted and mowed to allow for access, and you should not plant submerged plants that may clog irrigation intakes. On the other hand, if your pond is primarily for attracting wildlife, you can plant most of the shoreline including some types of submerged aquatic plants.
Right Plant Right Place:
You may have heard this Florida Friendly Landscaping term before, as it holds true for any garden including aquatic gardens. Choose plants that grow best in the water depth and planting “shelves” you have in and around your pond. By “shelf” we are referring to the slope of your shoreline. Is it a gradual, gentle slope into deeper water, or is it steep and abrupt? Also, become familiar with seasonal changes in your pond’s water depth, as it may affect the plants you select.
Prepare For Maintenance:
Just like a vegetable garden, your newly planted aquatic plants (especially those that are emerged) will need attention in the first year or so of establishment. Remove dead plants and weed out unwanted plants.
With all the news about the Zika virus spread in Florida, now is the time to start thinking about mosquito protection. As the weather warms, they will be hatching. Check out where the water is collecting in your yard. The female Aedes aegypti mosquitoes lay their eggs in temporary flood water pools; even very small ones such as pet watering bowls, bird baths and upturned Magnolia or Oak leaves. Dumping out the collection containers and raking through the leaves every couple of days can greatly reduce the population.
Becoming infected with Zika virus is not common. Though the disease can be transmitted by mosquitoes, blood transfusions or sex, the only know infections in Florida were from people who had been “bitten” by mosquitoes while travelling to countries with active virus outbreaks. That is until this past week, when a person-person infection occurred between a man that had been infected while out of the country and the woman he returned to in Florida. Mosquitoes usually obtain the virus by feeding on infected people, who may not exhibit any symptoms because they have been exposed and their body has built an immunity to the virus. Once the mosquito has drawn infected blood from the person, the infected mosquito “bites” another human, transmitting the virus mixed in saliva into the blood stream of the second host. If the second host is a susceptible pregnant woman, there is a risk of birth defects for the unborn child. If the infected host is a man, he can transmit the virus in semen for about two weeks.
Government public health officials here in Florida are able to monitor mosquito-borne illnesses quickly and effectively. Though the daily news can be alarming, the awareness is truly the message.
To protect yourself and reduce the sources for mosquitoes to breed, here are a few pointers:
Stay indoors at dusk (peak mosquito biting time).
If you must be outside, wear long sleeves and pants and/or mosquito repellents containing the active ingredient DEET.
Repair torn door and window screens.
Remove unnecessary outside water sources.
Flush out water collected in outdoor containers every 3-4 days.
Disturb or remove leaf litter, including roof gutters and covers on outdoor equipment.
Apply larvicides, such as Bacillus thuriengensis israelensis (BTI) to temporary water holding areas and containers.
The mosquitoes have been around all winter with the milder weather and frequent rain. As spring approaches they will be laying eggs on all the water surfaces they can find. As you venture out into the yard or travel to the great outdoors, remember to protect yourself and look at all the ways you can remove the potential habitats for the pesky creatures.
Giant Salvinia mats completely covering Bay County pond. This fast growing invasive can double in size every week! Photo by L. Scott Jackson
Matthew Phillips and Scott Jackson –
UF/IFAS Extension and Research works with many partners supporting invasive species management actions and strategies across Florida. One key partner is the Florida Fish & Wildlife Conservation Commission (FWC), Invasive Plant Management Section. FWC Biologists provide resources and expertise to address threats from Florida’s most disruptive invasive species. FWC and UF/IFAS have worked together for years. They have teamed-up to help residents make the best cost-effective management decisions to preserve unique habitats and ecosystems. Most days are filled with routine questions from land managers and pond owners but on rare occasions there are days we will never forget.
Active growing Giant Salvinia was observed growing out of the pond water on to moist soils and emerging cypress and tupelo tree trunks. Photo by L. Scott Jackson
Giant salvinia (Salvinia molesta) is an invasive free-floating aquatic fern from South America that is rarely observed in Northwest Florida. The species is on the Federal Noxious Weed List and the Florida Prohibited Aquatic Plants List. After a site visit with a pond owner, Scott Jackson, a University of Florida/IFAS Extension Agent, identified Salvinia molesta in the Bay County pond and notified the Florida Fish and Wildlife Conservation Commission’s (FWC) Invasive Plant Management Section. Their staff confirmed the identification of the specimen and a second voucher specimen was transferred to the Godfrey Herbarium at Florida State University.
Giant salvinia has caused severe economic and environmental problems in Texas and Louisiana and in many countries including New Zealand, Australia, and South Africa. Giant salvinia grows rapidly and produces a dense floating canopy on the surface of ponds, lakes, and rivers. It aggressively spreads by vegetative fragments and thrives in slow-moving, nutrient-rich warm fresh water. Floating mats of giant salvinia shade out native submersed vegetation and degrade water quality.
Mats also impede boating, fishing, swimming, and clog water intakes for irrigation and electrical generation.1 Salvinia molesta has been listed in The World’s Worst Weeds – Distribution and Biology2 since 1977. It was recently added to 100 of the World’s Worst Invasive Alien Species, an all taxa list compiled by invasion biologists with the Global Invasive Species Database.3
Photo by Barry Rice, sarracenia.com, Bugwood.org Rows of egg beater or light bulb shaped leaf hairs are a unique identifying characteristic of giant salvinia.
The location of the giant salvinia infestation found by Jackson is precariously close to Deer Point Lake, a 5,000 acre water body that is the main source of drinking water for Panama City and surrounding Bay County. The 2.5 acre infestation was on a 3.6 acre divided pond and both sections were treated. Treatment of the infestation was initiated by FWC in June 2013 at no expense to the property owners.
Bay County pond with no observed Giant Slavinia. Taken Oct 2013 by Derrek Fussell, FWC.
The pond continues to be monitored and, to date, there have not been any signs of living Salvinia molesta. We will continue to monitor the pond to make sure there is no re-establishment of giant salvinia. Investigations continue to try and learn more about the introduction of the pernicious species to this isolated pond.
Read more about the successful treatment regime FWC Biologists used to control giant salvinia in Northwest Florida. This was published in Florida Aquatic Plant Management Society’s publication “Aquatics” – see page 5.
Northwest Florida can be a pond owner’s paradise. There is usually enough rainfall to keep ponds filled, catfish, bass, and brim are well adapted to the environmental conditions, and there is a long season to catch fish.
One of the biggest problems pond owners face is the constant struggle with pond vegetation. Some pond vegetation is good. It provides a cover for young fish, helps stabilize the shoreline or bank, and some vegetative species are attractive wildlife.
However some species are highly invasive and can completely overtake a pond. One such species is water hyacinth (Eichhornia crassipes).
The water hyacinth is a floating plant, which if left unchecked and allowed to grow to its maximum potential, can weigh up to 200 tons per acre of water. In rivers, it can choke out other vegetation and make navigation difficult to impossible.
Water hyacinth, as an ornamental plant, is a wolf in sheep’s clothing. The plants intertwined and form huge floating mats which can root on muddy surfaces, as seen in the photo below.
The plant will be several inches tall, has showy lavender flowers, with rounded, shiny, smooth leaves. These leaves are attached to spongy stalks that help keep the plants afloat. The prolific roots are dark and feathery.
In Northwest Florida this pest commonly dies back in the winter. Unfortunately it is able to regrow when the weather and water warm.
Water hyacinth is not a native species. It is believed to have been introduced into the U.S. in 1884 at an exposition in New Orleans. Within 70 years of reaching Florida, the plant covered 126,000 acres of waterways (Schmitz et al. 1993).
Water hyacinth is on the FL DACS Prohibited Aquatic Plant List – 5B-64.011. According to Florida Statute 369.25, “No person shall import, transport, cultivate, collect, sell, or possess any noxious aquatic plant listed on the prohibited aquatic plant list established by the department without a permit issued by the department.”
To control a small infestation, the plants can be gathered from the surface, brought to the shore, left to dry and then disposed of in the garbage. There are biological control options—water hyacinth weevils will be useful in keeping the plant populations down.
The spongy petiole helps keeps the plant afloat.
Finally, chemical herbicide options may be the best alternative. University of Florida Aquatic Vegetation Specialist, Dr. Langeland, wrote Efficacy of Herbicide Active Ingredients Against Aquatic Weeds, a good publication that will help you to determine which herbicide will work best for different weeds.
NOTE: The middle of the summer is generally not the ideal time for applying herbicide on pond vegetation. For more information on weed control in Florida ponds, please see Weed Control in Florida Ponds. If you have any questions about identifying a pond weed, contact your local county Extension agent.
These days many ponds are just backyard recreational ponds. Management goals vary from owner to another. Some pond owners want very little productivity (very little fish removed). They want little vegetation with just a few fish. This pond is just meant for relaxation and aesthetics. Other pond owners want to fish every once in a while but primarily just want to enjoy the wildlife that’s attracted to it. And then others want to manage their ponds for great fishing whether it’s trophy bass, trophy bluegill or just a good balance of the two.
Each goal has very different management practices associated with it. When a pond owner asks about a management practice like fertilization, my first question to them is, “What is your goal for the pond?”
For a pond that is just for aesthetics with maybe a little fishing, I would recommend not fertilizing it. Once pond fertilization has started abruptly stopping this practice can lead to fish kills and re-establishment of rooted plants across the bottom.
When nutrients are added into a pond, they eventually make their way into fish tissue. They can be removed from the pond in the form of removing the fish to keep the pond balanced. Also, fertilization increases the number of microscopic plants, phytoplankton, that are suspended in the water. This gives the pond a green color and can block sunlight to rooted plants along the bottom of the pond. Microscopic plants are the bottom of the food pyramid in the pond. An increase in these plants leads to an increase in the number of fish in the pond.
I would only recommend beginning a fertilization program if a pond is going to receive heavy fishing pressure and the pond owner is willing and able to commit to continuing the fertilization program.
The desirable pond pH for fishing is 6.0-8.0. Some panhandle soils are acidic and have a lower pH value. You can raise the pH by adding lime but always test your water pH before adding lime.
Pond owners should monitor the water clarity using a secchi disk. The secchi depth will tell the pond owner if fertilization is needed or if the pond is in need of aeration. Each year, the fertilization program should begin when water temperatures exceed 65°F and end the program when they fall below 70°F. You can read more at Fertilization of Fresh Water Fish Ponds
Monitor your ponds closely throughout the spring and make any necessary herbicide applications before weed growth becomes too excessive. Photo Credit: Mark Mauldin
Similar to Goldilocks’ porridge, water temperature doesn’t need to be too hot or too cold, it needs to be just right for using aquatic herbicides (70o – 80o F). Here in Florida, these optimum water temperatures occur in the spring. Water temperature largely regulates the growth of most aquatic weeds; cool temperatures slow or stop growth and warm temperatures promote growth. Keeping this simple principle in mind can help determine when to use aquatic herbicides.
Generally speaking, aquatic herbicides are not used when water temperatures are below 60o F. When water temperatures are this cool most aquatic weeds are not actively growing. For herbicides to be effective the target plants must be actively growing. Applying herbicides too early in the spring is generally not an issue because winter dieback can make many aquatic weeds hard to find when water temperatures are cool. The weeds are out of sight and out of mind. The much more common issue is waiting too long before attempting to control weeds.
As water temperatures climb above 60o weeds begin to grow. Unfortunately, they often times grow unnoticed throughout the spring until they become completely out of control in the summer. By this point, control, even using herbicides, is a monumental task. If at all possible, control weeds early in the growing season.
As plants grow they are able to build up energy reserves, making them more difficult to control. The longer they are allowed to grow the stronger and more difficult to control they become. Controlling weeds earlier in the growing season eliminates this problem.
Similarly, as the growing season progresses plants produce more and more biomass. If an herbicide is applied and the weeds are killed large amounts of decomposing plant material in the water can cause problems. The decomposition process uses oxygen; dissolved oxygen can drop to levels that are hazardous to fish and other aquatic species. The more plant material that is present when herbicides are applied the bigger concern this becomes. Applying herbicides earlier in the growing season, before large amounts of biomass are produced, can help lessen this problem.
Aquatic weeds can grow rapidly when temperatures are warm. Don’t let them get out of control before you begin control efforts. Photo Credit: Mark Mauldin
Further compounding the issue, warm water is physically able to hold less dissolved oxygen than cooler water. Late in the summer pond water can be very warm with low concentrations of dissolved oxygen even before large amounts of decomposing plant material are added.
To help reduce the risk of oxygen depletion never treat more than ½ of a pond at one time, if weed growth is already substantial treat no more than 1/3 of a pond at one time and always allow 10 -14 days for oxygen recovery between treatments. Also, avoid treating on cloudy days, another factor that can lead to lowered dissolved oxygen.
Aquatic weed control will be easier and more effective if you monitor your pond throughout the spring and make any needed herbicide applications early, before the weeds have grown too large and the water is too warm. Consult your county extension agent for assistance determining what aquatic weeds you have and if treatment is necessary. Always read and follow all label directions when using any herbicide.
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