EWM is an evergreen plant. It must be killed or removed!
The plant remains alive over the winter and starts growing when water temperatures reach 50o F. EWM begins growing earlier in the season than the native water-milfoils. This makes early spring chemical treatment an option for control of EWM as it is more selective for EWM than late spring or summer treatments.
In spring and summer, EWM can grow up to two inches a day. If EWM plant growth reaches the surface of the lake, the plant will continue to grow and can form a canopy over the surface of the lake often making the area nearly impassable with a motor boat. This canopy can also shade out native plants. Excessive growth affects recreational use by interfering with swimming, fishing, and boating and reducing the aesthetics of the lake.
EWM grows in water depths ranging from less than one-foot to over 20-feet. Thick beds can form in water depths from 3 to 20 feet deep, but most commonly reach nuisance levels in water depths of 6-15 feet.
EWM is tolerant of disturbance and can grow in most water conditions.
One way to protect your lake from EWM or other invasives is to maintain native aquatic plant beds.
EWM produces seeds and runners, but the main method of spread is through plant fragmentation (vegetative propagation) by boats and wave action.
In the late summer and early fall, auto fragmentation may occur. Auto fragmentation is when the plant “breaks itself into smaller pieces”. Plant cells at leaf nodes and side-branch connections become weak, die and break off. These newly formed fragments float to new locations where they fall to the substrate, root and establish new beds of EWM.