Tompkins Weekly 11-18-13

By James A. Balyszak

Cayuga Inlet Hydrilla Project
2013: A Year-End Retrospect

When new patches of the highly invasive aquatic plant hydrilla (Hydrilla verticillata) were found in Fall Creek and the southeast corner of Cayuga Lake in August, the Hydrilla Task Force of the Cayuga Lake Watershed responded quickly. 

Within days of the discovery of the isolated hydrilla patches in Cayuga Lake, a team of divers (led by Racine-Johnson Aquatic Ecologists) worked within netted barriers to physically remove the patches from the lake bottom by hand.  Stray fragments were captured in the netting and removed. Following physical removal, fabric mats (known as benthic barriers) were placed over the area to prevent sunlight from hitting the bottom and suppress any possible hydrilla regrowth. Results from this control method were successful, and continued monitoring and sampling in the area has not found any signs of hydrilla regrowth.

To address the hydrilla growth in Fall Creek, including Stewart Park Pond and the golf course backwater, a single herbicide treatment was implemented on September 26. The contact herbicide endothall was used based upon the successful results observed in the Cayuga Inlet treatments. With assistance from the Tompkins Co. Sheriff’s Office, the treatment area was closed for approximately 6 hours while licensed herbicide applicators from Allied Biological, Inc. applied herbicide to the area. Once again, successful results were observed following this treatment, with the vegetative hydrilla growth (above the sediment) being killed quickly. It is important to note that the elodea population, a native aquatic plant, remained green and lush following treatment. A good indicator that the native plant population was not adversely impacted by the endothall treatment.

Although these new discoveries were a setback, the Task Force is still optimistic about winning the battle against this highly invasive plant; due to the success of herbicide applications to date and early discovery of the new infestations. The Fall Creek and Cayuga Lake treatment zones will be incorporated into the overall Cayuga Inlet Hydrilla Management Plan moving forward.

As in 2012, two herbicides were used in the Cayuga Inlet in 2013. On July 16, a preliminary one-day herbicide treatment of endothall was used. A month later, application of the systemic herbicide fluridone started. The 60 day, low-dosage application of fluridone was completed October 15. For the second consecutive season, the Task Force saw positive results from this combination treatment. Greater than 95 percent of the vegetative hydrilla growth (above the sediment) was killed as a result of the endothall treatment, while the subsequent fluridone treatment suppressed additional vegetative growth for the season. The result? Very little hydrilla growth was observed in the Cayuga Inlet. This means that hydrilla was not growing near the water’s surface where boats could fragment and spread the plant.  Also, the hydrilla plants did not have enough energy to form tubers or turions, structures necessary for spread and overwintering. Eliminating tubers and turions is essential for eradication. In 2011, hydrilla tubers in the inlet sediment numbered 300 or more per square meter. After treatment this season, recent sampling in the inlet is showing approximately .01 tubers per square meter!  An incredible reduction!

Ongoing plant and water sampling is a critical component of the overall Cayuga Inlet Hydrilla Eradication Project, and is conducted in concert with the herbicide treatments. As with most invasive species infestations, early detection and rapid response is crucial to the success of an eradication program. Monitoring and sampling allows the Task Force to assess treatment efficacy, observe the native and invasive plant community, and maintain water quality and health standards. Monitoring and sampling will continue through the end of the 2013 season and resume again in spring of 2014.

Over the coming months the Hydrilla Task Force will review and asses the treatments to date and plan for the 2014 treatment season. It is imperative that hydrilla be addressed now, in an effort to eliminate the local infestation and prevent its spread to the Finger Lakes and Great Lakes. With the work being conducted by the Hydrilla Task Force and its stakeholders, we would like to remind the community that there are several ways they can assist in our efforts. Most importantly, make sure to clean your boats and equipment of all plant fragments and debris BEFORE and AFTER launching in a water body. This includes motorized watercraft, canoes, kayaks, paddleboards, etc. Members of the community can also become Hydrilla Hunters, and assist in our efforts to educate the community and keep an eye out for hydrilla and other suspicious plant growth! More information can be found at cayugalake.org/hydrilla-hunters.html. For training and volunteer opportunities please email: steward@cayugalake.org.

As always, more information about hydrilla, why it is a problem, and what is being done to address it, can be found on our website at: Stophydrilla.org OR by contacting the Hydrilla Program Manager James A. Balyszak at 607-253-2340 and at stophydrilla@gmail.com.