Mechanical/Physical Control Options
Bladderwort can be removed by raking or seining it from the pond’s surface.
Fertilization to produce a phytoplankton or algal “bloom” prevents the establishment of most bottom rooted aquatic weeds and produces a strong food chain to the pond fish.
Biological Control Options
Grass carp will seldom control aquatic vegetation the first year they are stocked. They will consume bladderwort. Grass carp stocking rates to bladderwort are usually in the range of 7 to 15 per surface acre. In Texas, only triploid grass carp are legal and a permit from the Texas Parks and Wildlife Department is required before they can be purchased from a certified dealer (the list is at the end).
Chemical Control Options
The active ingredients that have been successful in treating bladderwort include 2,4-D (G), diquat (G), and fluridone (G), and imazamox (G). E = excellent, G = good
Navigate and Weedar 64 are 2,4-D compounds that have been effective on bladderwort. 2,4-D compounds are systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.
Reward is a liquid diquat formulation that has been effective on bladderwort. It is a contact algaecide and herbicide. Contact herbicides act quickly and kill all plants cells that they contact.
Sonar, Avast , and Whitecap are floridone compounds and comes in both liquid and granular formulations and have been effective on bladderwort. These are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.
Clearcast is a liquid imazamox formulation. It is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) is needed for application.
One danger with any chemical control method is the chance of an oxygen depletion after the treatment caused by the decomposition of the dead plant material. Oxygen depletions can kill fish in the pond. If the pond is heavily infested with weeds it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion.
One common problem in using aquatic herbicides is determining area and/or volume of the pond or area to be treated. To assist you with these determinations see SRAC #103 Calculating Area and Volume of Ponds and Tanks.
Many aquatically registered herbicides have water use restrictions (See General Water Use Restrictions).
To see the labels for these products click on the name. Always read and follow all label directions. Check label for specific water use restrictions.
Bladderwort can be transferred as whole plants during the spring. They should be put in clear shallow areas of the pond.