Pond Boss Forums GENERAL QUESTIONS Help Does pondweed contribute to algae?

Okay two submerged weed species. American pond weed is not nearly as bad nor as aggressive as the curly leaf (CL) . The two weeds have different primary growth periods or seasons. APM is primarily a warm season plant and Curly leaf is a cold season plant. IMO APM is beneficial due mainly to its lack of depth spread, its niche and behavior in the pond. Eventually the CL will create enough water clarity to allow it go grow into the center of the pond. CL is an invasive species from Europe. Grass carp (white amur) do not readily eat CL due to the coarser plant textures especially when the hard dormant turions form. Amur will eat APM and can denude it from the pond - a bad thing because you want some APM to compete with the filamentous algae(FA). You kill or eliminate all the submerged weeds and FA will replace all the plant growth biomass as FA or some other nuisance plant. Accumulated nutrients dictate how much plant growth occurs. Lack of competition determines what or which plants grow and by how much to use all the available nutrients that have entered the pond.

I hate CL and always fight it in my three ponds. I have frequently used the weed razor. It is a lot of work and is not very effective in cutting and removing all the CL. The good thing about CL is it floats when cut. The other early invader plant that will likely become established in your pond is Chara - technically it is a true algae and not a true aquatic macrophyte. The stuff that kills CL and APM will not kill Chara since it is an algae not a rooted vascular plant. Chara does not float when cut or raked. Amur eat Chara pretty well.

In my experience the easiest and cheapest way to annually reduce CL is to correctly use by label instructions a diquat product (37.3% active ingredient). FYI Weedtrine D is a dilute form of diquat. Diquat quickly chemically degrades in the with in a week or two after applied to the pond. In your 0.125 ac pond around 1 qt of diquat diluted with water around 5water:1diquat and sprayed or spread on the surface,,,, although it is better mixed and placed (injected) underwater into the beds of CL. A bottom aerator helps a lot to spread the chemical throughout the pond. Good distribution of chemical is key to the best success and results.

I say I annually reduce CL because all the old dormant turions can sprout into new plants years after they are formed and drop to the bottom. Plus a treatment often does not kill all the hidden - remote CL which will produce some turions for the next growth season. Treatment may only need to be done every 2-3 years???

CL typically sprouts from mostly the turions in late summer and grows until the water gets cold around 50F or lower. It as a cold season plant vegetates as a healthy plant on the bottom all winter long and grows again quickly in spring when water gets above 50F. When pond dye is not used it reaches the surface when the water gets to around 70F+ and produces seed heads at the surface while also forming the dormant turions. Pond dye can slow the seasonal growth cycle. After the seeds mature the plant usually dies back, turions sink to the bottom. Most of the turions sprout new plants in late summer to start the growth cycle again. Chemically treat the CL BEFORE the turions and seeds form.

I have chemically treated CL successfully in fall and or early spring before the vegetation reaches the surface. Another common aquatic herbicide that can be used to kill the CL is a fluridone product such as Sonar. Floridone has other brand names. I think if you apply diquat early spring (water 50F to 57F) before the APM sprouts in spring, the diquat MIGHT not kill the APM. No guarantee on this assumption. Your pond needs some sort of beneficial plant to help use nutrients and compete against a strong invasion of FA that will occur when all the CL and APM is eliminated. Nature DEMANDS that some plant uses the available nutrients that increase more each year of the pond’s existence. That is Nature’s law. The pond is a big bathtub with no drain if the pond is not flushed or does not have a water flow through cycle. Thus each year more nutrients that grow plants accumulate in the pond.