People often talk about their ponds or favorite fishing hole on the lake being choked out by hydrilla, but few of us - including myself - really understand what Hydrilla verticillata really is and the damaging effects it has on water ecosystems.  I picked up the latest copy of Aquatics this week and read the feature article on hydrilla eradication from Clear Lake, CA - a site commonly referred to as the “Bass Capital of the West”.  Bass enthusiasts might recognize this premier fishing destination as the producer of the 122 lbs. 14 ounces stringer from a Bassmasters Tournament.

Hydrilla is anchored to lakebed sediment by tubers that survive at least 4 years and can generate in excess of 30 million tubers per acre in ideal conditions…SCARY!!!  More often, tuber numbers are in the 3-5 million tubers/acre range.  Hydrilla is such a persistent pest because of their tubers which aren’t vulnerable to most ordinary commercial aquatic herbicides.  Among its more damaging effects are the clogging of irrigation canals, hydroelectric intakes in dams, and interfering with boating activities.  At high concentrations, hydrilla can harm local fish and wildlife.

How can hydrilla be exterminated?  Grass carp consider hydrilla a delicacy and some lakes such as Lake Gaston, NC/VA, stock the triploid freaks at a rate of 10 fish/acre.  Copper herbicides such as Komeen and fluridones such as Sonar are effective at killing hydrilla plants and has a very low toxicity to desirable aquatic organisms such as fish and waterfowl.  A more strenuous method of removal is diving and uprooting the hydrilla, but this method causes an over-disruption of lake bottom sediments.  Mechanical harvesting of hydrilla can be effective but runs the risk of creating floating mats of hydrilla and fostering new infestations at different sites in the lake.