Gladwin and Midland Counties, Michigan
Eurasian milfoil can form a dense canopy at the lake surface.
Eurasian milfoil (Myriophyllum spicatum) is an invasive aquatic plant that was first introduced to the United States in the 1940s. Although it is an exotic species, it is currently widespread in the state. Eurasian milfoil is problematic in that it becomes established early in the growing season and can grow at greater depths than most native plants. Eurasian milfoil often forms a thick canopy at the lake surface that can degrade fish habitat and seriously hinder recreational activity. Eurasian milfoil can spread rapidly by "vegetative propagation" whereby small pieces break off, take root, and grow into new plants. Once introduced into a lake system, Eurasian milfoil may out-compete and displace more desirable plants and become the dominant species. Controlling the spread of Eurasian milfoil is the primary focus of the plant control effort in Wixom Lake.
Eurasian milfoil is not the only type of milfoil found in Michigan. There are several native milfoil species that also grow here, such as northern milfoil. Recent research indicates that Eurasian milfoil has begun to hybridize with native milfoil species. Invasive milfoil hybrids have been documented to be widely dispersed across the northern United States. Studies of are underway to better document the impact of hybrid milfoil.
Early in the growing season, biologists from Progressive AE conduct field surveys to identify and map the location of Eurasian milfoil in Wixom Lake. Care is taken to distinguish the Eurasian from the native species. These maps are then used to direct our plant control contractor to treat the Eurasian milfoil beds with selective herbicides.
In Michigan, a permit must be acquired from the Department of Environmental Quality before herbicides are applied to inland lakes. The permit lists the herbicides that are approved for use, respective dose rates, use restrictions, and indicates specific areas of the lake where treatments are allowed.
Within a few weeks of treatment, biologists perform follow-up surveys to evaluate the effectiveness of the treatments. Vegetation monitoring surveys are essential to help ensure Eurasian milfoil and other invasive species do not gain dominance in Wixom Lake.