Aquatic Plant Management Methods

December 7, 2017

Non-native aquatic plants and excessive plant nutrients have created many aquatic plant management problems for lakes and streams. There have been many methods developed to eradicate and control nuisance lake weeds.

In addition to manual removal, mechanical cutting and the use of aquatic herbicides, there have been several new, more exotic methods introduced in aquatic plant management.

Sediment Agitation: consists of keeping a beach area agitated with a roller or other device which separates the nutrient-rich sediment from the sand and heavier soils of the lake bottom. The simplest version of this is slowly engaging an outboard motor while the boat is tied to a dock. The prop wash will blow weeds and soft sediment out of a small area very quickly.

The problem with this aquatic plant management method is it creates many thousands of plant fragments which quickly settle, take root and begin growing new weeds. The roller machines don’t cause as much weed fragmentation, however, they only cover a small circular area and are usually attached to a dock. But for some small applications, sediment agitation can be an effective method of aquatic plant management.

Rotovation: is essentially sediment agitation combined with an underwater rototiller blade that digs out plants by the roots and disturbs the sediment on the lake bottom. Commercial machinery is usually used for this type of management. It’s expensive, causes massive fragmentation and weed re-growth.

Grass Carp: This fish is considered an invasive species yet it is stocked in many states as an aquatic plant management option. The carp feeds on aquatic weeds. When used for weed control, the grass carp introduced to the pond or stream are sterile. In some cases grass carp have been an effective aquatic plant management method. In other cases they’ve either failed to control weed growth, or they’ve eaten all the submerged plants.

Biological Control: An innovative method of aquatic plant management is the introduction of organisms such as the milfoil weevil, that feed on invasive lake weeds. The milfoil weevil is perhaps the most successful example of using biological control to manage a specific invasive weed, in this case, eurasian milfoil.  Although this aquatic plant management technique of using insects to control invasive plants has been used to some degree for a century, it is not in widespread use at this time.

Water Level Drawdown: In some lakes, the water level can be lowered via dams or weirs as a means of aquatic plant management. The drawdown in winter exposes the shallow lake bottom areas to both freezing and drying, which can kill off large sections of lake weeds. The downside is, it can promote other types of weeds that thrive in such conditions. The freezing of sediment will often kill hibernating animals such as turtles and frogs.

Benthic Barrier: This is the category of aquatic plant management that LakeMat® falls under. It is, in our opinion the single best method of aquatic plant management.

Here’s why: