The occurrence of aquatic weeds and algal blooms are as much a part of summer as eating watermelon and grilling.
Aquatic plants are usually viewed as a nuisance by pond owners, however many of these plants are necessary for healthy fish habitats.
Vegetated areas hold more fish than weed-free waters, but sometimes invasive pond weeds and algal blooms can overtake a pond and must be dealt with.
For pond owners, quick responses to the emergence of these plants is the key to eliminating them.
To determine a treatment for the weeds or algae, they must be properly identified. There are four types of pond weeds: algae, floating weeds, emergent weeds and submersed weeds.
The pond weed that creates the most concern for people is cyanobacteria or blue-green algae. Cyanobacteria produces toxins and odors that can irritate skin, cause liver damage and even affect the brain.
What makes cyanobacteria difficult to control is that the treatment for it releases more toxins into the pond for weeks.
Ideal conditions for toxic algal blooms to appear are stagnant waters that get direct sunlight, warm temperatures and high nutrient content.
Although many herbicides are labeled for use on pond weeds, the application of these herbicides must strictly follow the label to ensure oxygen is not depleted to the extent that results in fish kill.
A common way to treat pond algae is with copper-based algaecides, but the best way to manage pond algae is to prevent it from reoccurring by using integrated management practices.
Aeration, creating a 10’ to 20’ buffer zone of tall vegetation, decreasing fertilizer rates and fencing off the area around the pond to prevent livestock contaminating it are all effective management practices that prevent the occurrence of algal blooms.
Another method of algae prevention is to stock ponds with tilapia or grass carp that will feed on submerged plants.
If you have any questions about pond weed management, please contact your local Extension office.
