Impact of Management on the Sprouting of Dioecious Hydrilla Tubers

• Published in: Journal of aquatic plant management 2006-01, Vol.44 (1), p.32-36
• Main Authors: Netherland, MD, Haller, W T
• Format: Article
• Language: English
• Subjects: Freshwater; Hydrilla
• ISSN: 0146-6623

The dioecious biotype of hydrilla (Hydrilla verlicillata (L.f.) Royle) was established twice in mesocosm tanks (900 L) during September 1996 and 1997 in Gainesville, Florida. Hydrilla shoots were planted in 10-cm diameter PVC cores with a hydrosoil depth of 30 cm to allow for biomass establishment and tuber formation during the fall, winter, and spring. In late May 1997 and 1998, the dense hydrilla canopies were controlled by using the aquatic herbicide endothall (7-oxabicyclo [2.2.1]heptane-2,3-dicarboxylic acid), by mechanically clipping the canopyjust above the hydrosoil, or by using endothall to remove biomass followed by replacement with healthy non-rooted hydrilla shoots to simulate the presence of a plant canopy. The sprouting of quiescent in situ tubers was then recorded at 4, 8, 12, and 20 weeks following treatment. Light availability at the sediment surface and sediment temperatures increased following canopy removal, whereas these values were similar for the control and artificial canopy treatments. Total tuber sprouting remained below 20%, and was not impacted over the 20-week study period by any of the treatments when compared to the controls. Results of these mesocosm trials suggest that chemical or mechanical management efforts have no discernible impact on the short-term sprouting of hydrilla tubers in situ.