Hydrilla: AN AGRESSIVE WATER WEED
WHAT'S NEW:
- April 2012: The Local Hydrilla Task Force has drafted an initial Hydrilla Work Plan (152 kb pdf). This is a first attempt to articulate the various tasks, and estimated costs, that are expected to be needed to reach the goal of eradication. It was pulled together by the Local Task Force section of the larger Cayuga Inlet Hydrilla Task Force. There will be changes made along the way as we work with our State and Federal partners and develop the larger Management Plan.
Fluriodone FAQs: herbicide proposed for 2012 after an initial treatment of endothall
- State legislators recognized for securing funds to fight hydrilla (March 29, 2011)
- Upcoming events to learn more about hydrilla.
- Hydrilla linked to eagle deaths. Research by Warnell School of Forestry and Natural Resources. Hydrilla linked to bluegreen algae toxicity in eagles (618 kb pdf). And an article about more recent eagle deaths along the Georgia-South Carolina border.
About Hydrilla
The highly invasive aquatic plant, Hydrilla verticillata, known commonly as 'hydrilla' or 'water thyme' was recently detected in the Cayuga Inlet by staff from the Floating Classroom. In a follow‐up survey, Robert L. Johnson, a local plant expert with Cornell University and Racine‐Johnson Aquatic Ecologists, located several areas of the Inlet with extensive populations of hydrilla. To date, hydrilla appears to be localized to the Cayuga Inlet, with no evidence that it has yet rooted in Cayuga Lake. View image of hydrilla and look-alikes, that is other water plants that look similar to hydrilla.
This is the first detection of hydrilla in upstate New York's waters, and the risk of it spreading to Cayuga Lake and other regional waterbodies is substantial. Fragments of the plant, which are easily caught and transported by boats and boat trailers, can sprout roots and establish new populations. Fragments also float and are capable of dispersing via wind and water currents.
Hydrilla grows aggressively, up to a foot a day.1 Early in the season, it grows mostly horizontally along the bottom of the waterbody. Side shoots and new tubers can develop at the nodes as the plant grows. As the water temperature increases, the stems elongate, sending the shoot tips, which can themselves grow an inch a day, toward the water surface.
The plant creates a thick mat of vegetation when it reaches the water's surface. It quickly shades out other aquatic plants, displacing native species like pondweeds and wild celery.
Hydrilla has long slender stems that can grow underwater to lengths of up to 25 feet. Its identifying characteristics are four to eight small, pointed leaves arranged in circular whorls along the length of the stem. The edges of the leaves are lined with sharp teeth. Hydrilla is often confused with native water weeds, particularly Elodea canadensis whose leaves typically occur in whorls of three and appear smooth‐edged. It also resembles the invasive Brazillian waterweed (Egeria densa), which is found downstate in New York and has finely serrated leaves (3/4 ‐ 1.5 inches) in whorls of 3 to 6. Hydrilla can set seed, but primarily reproduces vegetatively via floating pieces that set roots, buds produced along the stems (called turions), or overwintering tubers. Please visit http://nyis.info for up‐to‐date information about hydrilla and other invasive species. (Adapted from a press release by New York Invasive Species Research Institute at Cornell University)
Photo of Hydrilla verticillata by Chris Evans, River to River CWMA, used courtesy of Bugwood.org.
1. Glomski, L.A. and M.D. Netherland. 2011. Does Hydrilla Grow an Inch Per Day? Journal of Aquatic Plant Management. (click to go to full report)
