Preserve Year-Round Beauty with Fall Aquatic Maintenance
As we approach shorter days and cooler temperatures, pond and lake management should remain a priority. Waterbodies constantly adapt and change, and frequent observation allows for a more proactive, adaptive, and successful management plan.
Surveying your aquatic area to assess the plant distribution and composition is integral in managing your waterbody. Through fall surveys you can assess how the summer management plan worked and what adjustments are necessary. You can also better plan for the spring by mapping your vegetation and knowing where to expect plants to reappear. This is important for proactive management strategies, especially when using an herbicide such as Fluridone to control nuisance or invasive vegetation.
By knowing where your plants are ahead of time, you can apply Fluridone in the early spring when the unwanted species are just emerging from the waterbody floor, and before they reach the surface of the water. In areas with more moderate temperatures, this could even be done throughout the winter when your reservoirs are not being used for irrigation purposes. This will result in less herbicide use, a decreased rate of sedimentation, and reduced risk for fish kills through dissolved oxygen depletion.
As vegetation is decomposed, bacteria and other microorganisms consume large amounts of oxygen as they convert the dead vegetation into sediment. If large volumes of biomass are being decomposed at once, too much dissolved oxygen can be consumed which can trigger a fish kill. Over time, these sediments will accumulate reducing the depth of your pond which can result in a myriad of issues that can be detrimental to the health of the ecosystem, recreation opportunities, and overall aesthetics. Ultimately these factors will result in the eutrophication of your waterbody and the dreaded algae bloom. If you treat early in the season, when plants are still small, there is less biomass decomposition which ensures a healthy concentration of dissolved oxygen is maintained and a decreased rate of sedimentation.
The widely distributed invasive species, curly-leaf pondweed (Potamogeton crispus), will prosper through the fall and winter months and emerge in alarmingly dense distributions in the early spring. Curly-leaf pondweed produces and drops turions, a reproductive structure, in the fall. The turions allow this plant to spread and sprout in the early spring. As a result, curly-leaf pondweed is often the first submersed aquatic plant to reappear after the winter. By retreating regrowth and other existing curly-leaf pondweed in the fall, the amount of turions produced and their overall density will be reduced the following season. Diquat and Flumigard SC are two great choices for treating this plant due to their fast mode of action and relative ease of use.
In the Western United States fall and winter are also excellent times to apply a pre-emergent program to your de-watered canals. Long-lasting herbicides like Imox and Fluridone will bind to the bottom of your earthen canals providing lasting plant control into the spring watering season. Combining either of these together or with Flumigard will provide excellent control of existing plants with the benefit of lasting pre-emergent action.
During the summer months, the water in your pond or lake will stratify into a warm layer found on top of a cold layer that sinks to the bottom. The area between these two layers is referred to as the thermocline. You may notice this when swimming in a lake during the summer as the upper portion of the water is comfortably warm, and you feel much colder water near your feet. Often times nutrients are trapped in the cold dense water at the bottom of the waterbody. In the fall, as surface water decreases, these previously separated layers mix. This brings cold, nutrient-rich water to the surface where the sun penetrates the water column and algae thrive. With an influx in nutrients, algae composition will often bloom to harmful levels as more “food” becomes present. Numerous species of algae can produce toxins and irritants which can have negative health effects on both humans and animals that consume, touch, or are around the organisms. Increased algae presence can also trigger a fish kill, through large-scale decomposition events when the organisms die. It is important to keep algae volume at a healthy level using an algaecide such as Argos to minimize all potential risks associated with harmful algae blooms.
Fall is an incredibly useful time to manage emergent and shoreline vegetation. As plants such as phragmites, cattail (Typha spp.), and waterlilies begin to prepare for winter, their growth and energy reserves are channeled to their roots and rhizomes to allow them to survive the winter and resprout in the spring. As a result, these plants become susceptible to long-term control through the application of herbicides such as Imox or Glyphosate 5.4. It is important to perform these treatments with enough time before the first frost to allow the plants to bring the herbicides into their root and rhizome structures to ensure long-term control.
There are many things to be considered when managing a waterbody. By taking a year-round approach and using an array of tools and strategies you can guarantee long-term and consistent health in your waterbody.
