Tuesday, July 8, 2014

Management Minute - Research continues to investigate the "growing" problem in Santee Cooper System

Photo Credit - NCSU AWCP
We often talk of the usual suspects in our blog postings here on the AERF update. Hydrilla, EWM, and Water Hyacinth are but a few species with which many of us in aquatic plant management have become quite familiar. Another not-as-well-known invader is taking over many waterways in the Southeastern United States leaving behind it clogged waterways and much lost both economically and ecologically speaking. Like many invaders before it, this plant, native to asia, gained a foothold in Florida in the early 1990s and was likely introduced as a water garden plant.

Photo Credit - NCSU AWCP
Crested floating heart (Nymphoides cristata) is an aquatic flowering plant that is characterized by its heart-shaped, floating leaves and “crested” white flowers. Floating heart has shown to be very aggressive establishing numerous populations throughout Florida. Although individual plants may look small and delicate, crested floating heart is a very “hearty” species. The plant has been known to survive water drawdowns and freezing temperatures of less than -30 degrees Celsius, suggesting the potential survival and spread of the plant throughout the rest of the United States.

In 2006, Crested floating heart was discovered in Clarendon County, South Carolina encompassing a mere 20 acres of a cove in Lake Marion, one of two extremely large lakes making up the Santee Cooper Lake system. The plant began to spread outside the cove into other areas of the Lake in late 2006/early 2007 and demonstrated the ability to infest open water areas and high energy areas devoid of native plant life. By 2010, the plant had spread to other areas of Santee System, encompassing some 2000 surface acres. Several attempts at removing and treating the plants were attempted; however the behemoth invasive still persisted after 2010. Based on suitable habitat for the plant, biologists estimate that crested floating heart could ultimately infest as much as 40% of the 160,000 acre Santee Cooper Lake System if not controlled. It was quickly apparent to resource managers that something had to be done with haste.
Aerial view of crested floating heart on Santee Cooper.  Photo Credit - EDDMAPS
Researchers from Santee Cooper, NCSU, and UPI.  
Officials with Santee Cooper along with NC State University began conducting surveys and research trials in order to find a long term control solution to the expanding floating heart infestation in the one of the Southeast’s largest water bodies. In 2013, the group along with representatives from UPI and Syngenta, began  treatments testing varying rates and combinations of each companies products: Aquathol, Hydrothol, and Reward.  Treatment timing (spring, summer, winter) was also investigated to determine how the plants life cycle might affect success.

- The first round of treatments took place in July 2013 as a foliar application. Trials revealed varying results based on these factors, however the group identified one combination out of those tested that produced quick knock down and extended control. A combination Aquathol (at 3ppm) and Hydrothol (at 0.18ppm) (both of the active ingredient endothall) produced knockdown of plants within 2 weeks and provided extended control out to ten months after treatment.
Pretreatment - 2WAT - 1MAT - 10MAT with combination

- The December 2013 treatments were applied using weighted drop hoses while floating leaves were still present but the plants had begun to senesce. During this treatment time, quick knock down was achieved using 1.5ppm Aquathol (active ingredient endothall) + 0.368ppm Reward (active ingredient diquat).
Pretreatment - 2WAT - 1MAT with combination

- The Spring 2014 treatments were applied when a small amount of vegetation was present in each plot using drop hoses to reach the root crown of each plant. No combination showed any effect in the spring treatment and greater levels of vegetation than were present at time of treatment.

This preliminary work of NCSU and Santee Cooper Officials suggests that timing may play a very critical role in impacting crested floating heart on such a large system. The group has planned additional studies and treatments, using both the products and active ingredients addressed in this study as well as others, to further investigate the best long term management plan for crested floating heart in this system. Continued work and testing will hopefully shed some light on controlling this plant before it too becomes as well known as the lineup mentioned earlier. 

To have your research considered to be featured on the AERF Management Minute, contact Brett Hartis at bmhartis@ncsu.edu.

For more information on Crested Floating Heart, check out the EDRR fact sheet or the University of Florida's Center for Aquatic and Invasive Plants.

Want to know if you have crested floating heart in your area?  Use this simple ID guide to tell it from other native or invasive floating heart species.

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