Curlyleaf pondweed control using copper-ethylenediamine alone and in combination with endothall

Authors: TURNAGE, GRAY - Mississippi State University; Madsen, John

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2017
Publication Date: 7/1/2017
Citation: Turnage, G., Madsen, J.D. 2017. Curlyleaf pondweed control using copper-ethylenediamine alone and in combination with endothall. Journal of Aquatic Plant Management. 55:116-119.

Interpretive Summary: Our research demonstrates that the invasive aquatic plant curlyleaf pondweed (Potamogeton crispus L.) may be controlled with a copper-ethylenediamine complex herbicide, either alone or as a tank mix with an endothall herbicide. This provides an additional mode of action for potential use in controlling this species, in addition to the widely used endothall herbicides. The advantage of the copper-complex herbicides is that they are approved by US EPA for use in water supply reservoirs and in irrigation waters.

Technical Abstract: Curlyleaf pondweed (Potamogeton crispus L.) is a submersed aquatic invasive plant species in the U. S., particularly in northern states. Curlyleaf grows rapidly and is capable of outcompeting native plant species for nutrients and resources thereby altering biotic and abiotic processes in infested waterbodies. Besides affecting native biota and ecological processes, curlyleaf forms a dense canopy that can inhibit human uses of a waterbody (i.e. fishing, boating, irrigation, etc.). Therefore, continued development of control strategies are needed to attain control of curlyleaf in infested waterbodies. Herbicides used to control curlyleaf are commonly applied in the weeks preceding turion production in the spring to inhibit this process and because this is a period when carbohydrate storage has been depleted and treated plants are less likely to recover from herbicide induced stress. While copper based herbicide formulations are commonly considered to be an algaecide, some formulations of copper are labeled for control of some submersed aquatic plant species. Curlyleaf was treated with copper-ethylenediamine and endothall separately and as tank mixtures. By four weeks after treatment, all herbicide treatments provided significant reduction of curlyleaf aboveground and belowground biomass and most had reduced turion biomass and number when compared to the untreated reference. At eight weeks after treatment, some treatments had started to recover aboveground and belowground biomass, however all but two treatments still had significant reduction of turions. The results of this study suggest that copper-ethylenediamine alone and in tank mixtures with endothall may be a viable treatment option for controlling curlyleaf biomass and turion production.