After the curlyleaf pondweed flowers in mid-summer, the surface mats break apart and begin to decompose, becoming a nuisance for lake residents and further negatively impacting environmental conditions. Like Eurasian watermilfoil, curlyleaf pondweed is spread primarily by human activities. The plant is difficult to control by conventional means because it forms propagules that remain in the sediments like seeds. Eurasian watermilfoil is a much greater problem in Perch Lake than is curlyleaf pondweed. It is used to selectively manage certain common aquatic nuisance plants and has been on the market since 1986.
Sonar works by inhibiting carotenoid synthesis in the target plant.
This results in photo-degradation of chlorophyl, thereby interrupting photosynthesis and stopping the plant's ability to make food. Depending upon the formulation, rate, and time of year it is applied, Sonar can be used to selectively control nuisance weeds while having a minimal impact on desirable native plants. For the purposes of this study, Aquatic Technologies Inc. applied the product at a rate of 8 to 9 ppb in the fall of 2000. The growth patterns of Eurasian milfoil and curlyleaf pondweed differ from native plant species. Eurasian milfoil remains actively growing later in the fall than native plants and begins growing earlier in the spring.