hydrilla will destroy the native aquatic community in many ponds, lakes, .... ponds are immediately upstream of Fellows Lake, a popular fishery and water.
Hydrilla Eradication – More Than Just Treating Plants Results:
Monitoring:
Control: Season-long treatments with systemic herbicides are working. Biomass and tuber monitoring are showing positive trends. In ponds where biomass was monitored with the rake test, the total volume of hydrilla during 2015 spring germination was much less than in 2014. This coincides with a marked reduction in overall tuber counts after one season of season-long control (Figure 9).
Figure 3. A sampling rake. Figure 3. A sampling rake.
Inspections: Water body inspections are used to identify stands and define plant range. Staff trained on hydrilla identification systematically search area water bodies for hydrilla from July through late fall. Search emphasis is placed on water bodies near known hydrilla stands and areas of high vulnerability such as urban lakes, waterfowl areas, and highpublic use areas. Depending on water clarity and depth, inspections are either visual and/ or rake-based. In areas of high clarity, visual inspections are conducted by walking the shoreline or down the center of a stream. In areas of low visibility, a double-sided bow rake tied to a rope is used to inspect water bodies (Figure 3). All types of water bodies are inspected through this process.
Hydrilla Volume - Lake 0
Voluma (Cubic Inches)
that was first documented in Missouri in 2012. Efforts to document hydrilla’s full extent in Missouri and develop an eradication plan started immediately after the discovery. The multi-year eradication plan was initiated in 2013 and uses a multifaceted approach. The plan’s three major components are Control, Monitoring, and Prevention. Control consists of chemical and biological measures to eliminate hydrilla biomass during the growing season for at least five consecutive years at each site. In 2015, control efforts were underway in 26 small impoundments throughout the state. The monitoring component encompasses evaluating the progress of existing control efforts and inspecting nearby waters and other waters highly susceptible to introduction to ensure containment (i.e. no spread). PrevenFigure 1. A close up of hydrilla. tion includes various outreach and education efforts to inform landowners and water users about the plant and routes of spread. Each year efforts in each component have progressively heightened with initial emphasis on control and monitoring. This year the prevention component received concerted effort by creating informational materials to distribute at special events, fairs, and to organized user groups. Some of the new materials included water resistant identification sheets for groups like Stream Teams, invasive species hydrilla fact sheets, tabletop displays and posters for special events, temporary tattoos for kids, and posters for canoe liveries and pet suppliers. All three facets of the plan are integral for protecting Missouri waters from hydrilla and will continue to be active components as we move forward.
Materials and Methods (cont.):
Introduction:
150 100
2015
50
2014
0 5/26
7/15
9/3
Date
Treatment site monitoring: Monitoring is used to evaluate herbicide concentrations, plant response to herbicide applications, and overall declines in tuber density. Monitoring is standardized by sampling/monitoring location, the number of attempts made to collect data at each site, and biomass quantification. Herbicide Application: Weekly fluridone herbicide concentration testing determines if sufficient fluridone levels are being maintained in the high water exchange impoundments. Water samples are bottled at 10 to 20 cm below the water’s surface, retained on ice, and transported to a certified laboratory where analyses of chemical concentrations are performed.
200
4/6
Lake 0 (Site 1) 70 60 Number Collected
Abstract: The aquatic invasive species hydrilla is a federally listed noxious weed
50 40 Total Tubers Collected
30
Inspection efforts are also aiding in the development of timelines for future introductions. Through annual inspections of the plant community in nearby impoundments, we will be able to catch any hydrilla introductions in the early stages. This allows treatment plans to be fine-tuned and can even allow for the reduction of control efforts if the plant is detected before it has a chance to put down tubers.
Total Turions Collected
20 10 0 2013
Hydrilla is an aggressive plant that many states have been dealing with for years. There is no simple remedy. Its ability to outcompete other aquatic plants, multi-year tuber viability, and ease of transfer via wildlife and human activities make it immune to one-time treatments or a one-strategy approach. Our goal is complete eradication of the plant. It will take several years to achieve this goal and our course of action is multi-faceted with three major components: Control, Monitoring, and Prevention. The strategies listed below give us the best opportunities to contain the plant and work towards eradication. If not eradicated, hydrilla will destroy the native aquatic community in many ponds, lakes, reservoirs and even streams. 1. Inspect water bodies for hydrilla and define its range (Monitoring). 2. Treat infested water bodies (Control).
Acquire signed agreements to ensure access to the water body during the entire treatment process.
Apply herbicides throughout the growing season to eliminate presence of any biomass at time of tuber production.
Stock Grass Carp as needed.
3. Monitor the treated areas throughout the growing season for resilient plants (Monitoring).
Plant Response: Rake biomass tests and visual observations are used to monitor chemical effectiveness throughout the hydrilla growing season. The rake test consists of tossing the rake sampler approximately 15 to 20 feet from the bank of an impoundment into a known hydrilla area, then dragging the sampler across the substrate back to the bank. Plant material is removed from the rake. Hydrilla is separated from other aquatic plants and placed in a container. This process is repeated three more times at the same general location and the total volume of collected hydrilla is quantified. Visual monitoring is utilized at sites that can not be rake tested due to heavy water lily stands. Visual monitoring consists of visual Figure 4. A treated stand of hydrilla showing chemical response. observation and photo documentation (Figure 4). Tuber Density: Tuber monitoring is used to monitor the amount of hydrilla tubers residing within a pond’s substrate. Core samples are collected from known hydrilla locations during the months of March and April (Figure 5). The samples are sifted and washed, and any tubers and turions are collected and recorded. A minimum of 20 samples is taken at each site.
4. Monitor hydrilla tuber density within the substrate of infested ponds (Monitoring).
2014
2015
Year
Figure 9. Graphs illustrating the effects of treatment on overall plant volume (top) , and number of tubers and turions (bottom).
Prevention: Our outreach efforts have allowed us to reach more landowners and water users. Hydrilla fact sheets distributed statewide to 10,800 Stream Team members 140 canoe livery operators around the state received hydrilla posters Hydrilla displays were set up at popular events including the Springfield Lawn and Garden Show, Ozark Empire Fair, and Missouri State Fair
5. Repeat above strategies each year until plants are eradicated.
25 pond owners in the immediate vicinity of existing hydrilla stands attended a pond workshop spring of 2015
6. Develop relationships with landowners in watersheds with hydrilla through one-on-one contact and landowner workshops (Prevention).
45 boat ramps are now stenciled with the prevention message of “Clean-Drain-Dry”
7. Implement outreach efforts through developing partnerships with local governments, utilities/water suppliers, watershed groups, and lake managers. This allows for training of additional staff on hydrilla identification and expanding outreach efforts (Prevention). 8. Educate the general public about hydrilla and its modes of transfer (Prevention).
Monitoring: Overall, inspection efforts led to the detection of five new ponds which will be added to the treatment list in 2016 (Figure 10). Some of these ponds are immediately upstream of Fellows Lake, a popular fishery and water supply lake in southwest Missouri. One of the ponds is in a new section of the upper Pomme de Terre watershed. By finding these ponds, treatment can be initiated and reduce the potential for spread into our public waters.
Figure 2. An infestation of hydrilla.
Materials and Methods:
Figure 5. Collecting core samples for tubers (left); sifting core samples through a screen (center); tubers and turions found in core samples (right).
Prevention: The key to preventing the spread of hydrilla is educating local resource management staff inside and outside the Department, nearby pond owners, and the general public. The Hydrilla Working Group formed in 2014 is comprised of resource personnel from multiple agencies. The group spearheaded several outreach efforts including the following:
Control:
City Utilities of Springfield bill insert reaching 110,000 households
Chemical and biological control methods are being used to combat existing stands of hydrilla. The aquatic herbicide prescriptions for treating hydrilla are based on water exchange rate, timing of treatment, and plant biomass:
Production and airing of a hydrilla commercial Media coverage (Print and TV)
Early Plant Biomass: Fast-acting contact herbicides are applied in early-May to knock back hydrilla growth. The appropriate systemic herbicide treatment based on water exchange rate follows within a week. Low-Water Exchange: Only systemic herbicides are used. Sonar® AS is applied three times at 30-day intervals at the rates of 15 ppb, 10 ppb, and 10 ppb. The first application is in early-June. High-Water Exchange: A combination of pelleted and liquid systemic herbicides are used. Sonar® PR (pelleted) is applied on three separate dates. The first application occurs in mid-May with the second and third applications occurring at 21- and 28day intervals, respectively. Sonar® PR is applied in impoundments with heavy hydrilla biomass at rates of 30 ppb, 20 ppb, and 20 ppb. Impoundments with sporadic hydrilla coverage are treated at rates of 10 ppb, 10 ppb, and 10 ppb. The pellets are applied using a backpack blower and herbicide spreaders mounted to the front of boats. Drip systems are also used to bump fluridone concentrations by slowly releasing Sonar® Genesis over a course of an eightweek period at rates ranging from 5 to 12 ppb per day.
Missouri Conservationist article
Discussion: As we enter 2016, 31 water bodies have been identified statewide as having hydrilla. Control, Monitoring and Prevention efforts will continue. All 31 ponds will be treated for season-long control of hydrilla. Tuber monitoring will commence in March 2016, and will provide a comprehensive evaluation of our 2015 efforts. Biomass monitoring will continue to be used to provide instant feedback on the 2016 treatment efforts. With the all the flooding that occurred in 2015, inspections of nearby water bodies and receiving streams will be intensified. If hydrilla was able to move during these events, it is imperative that we catch it before it has a chance to become established.
Missouri Department of Conservation website informational page Hydrilla fact sheets for Stream Teams and the general public (Figure 6) Hydrilla exhibits at popular public events such as fairs and special events (Figure 7)
Figure 7. 7. An An informational informational table table disFigure display. play.
Boat ramp stenciling (Figure 8) Canoe livery posters
Figure 11. Statewide hydrilla distribution.
Figure 6. A fact sheet created to help the public learn about hydrilla.
Late Season Treatments (Initial treatment starting in August or later): A combination of contact and systemic herbicides are used. Contact herbicides are used to treat half the pond. Then the appropriate Sonar® product is applied at 20 ppb . Figure Figure 8. 8. Stenciling Stenciling on on aa boat boat ramp. ramp. Grass Carp are stocked as needed to provide a secondary control method. Rates vary from 3 to 30 per acre.
Training of staff from other agencies on hydrilla identification and the inspection process has also proven successful as they were able to recognize hydrilla during a vegetation investigation and Figure 10. Inspection locations and results for southwest Missouri. promptly reported it to the Department.
Additional groups such as Stream Teams and Master Naturalists will be trained to help with inspection efforts and prevention methods. Currently, the City of Pleasant Hope and the James River Basin Partnership plan to distribute hydrilla fact sheets with their respective water bills and septic tank mailings. This will reach over 500 households. The Source Water Protection grant will be used for hydrilla and other aquatic nuisance organism prevention signage at Fellows Lake. The hydrilla commercial will be re-aired in southwest Missouri and introduced in the St. Louis metro area in 2016.
Authors: John Freese, L. Elizabeth Gray, and Kara Tvedt Affiliation: Missouri Department of Conservation—Southwest Region—Fisheries 2630 North Mayfair Avenue, Springfield, Missouri 65803
