New invasive plant in lake

Bobbie Bicknell Coray

Rich Civic Times

RANDOLPH, Utah.  March 11, 2020.   Matt Combs, Utah Forestry, Fire and State Lands, reported that a new invasive weed,the Eurasian Water Milfoil, was discovered last fall in Idaho.  It will negatively impact the lake.  Utah and Idaho are working together to develop a response.

The weed looks like the local milfoil, but this is an invasive weed.  It takes over shorelines and has a fisheries and recreational impact.  The potential for establishment is high.  Both Utah and Idaho want to be very aggressive with it.  If it hybrids with the  local milfoil  it will be harder to eradicate.

This milfoil is a perennial bushy plant.  Harrowing spreads it.  Combs did a quick triage and found it in several areas.  The marinas including the smaller ones on private property have it.   It grows in 30  to 40 feet of water especially in clear water. 

Combs said they are putting a treatment plan together such as chemical treatments where it is taken over areas of more than 1/2 acre.  They are doing some hand pulling in smaller areas. They can use a handmade mining dredge, but  mechanical treatments take a long time.

Because of the growth pattern they will have to spray in July which is the busiest tourist time.  They will use a specific chemical for milfoil. 

 

The weed on the Idaho  side is spreading even more there.  The weeds make the water murky especially in a marina.  It gets into the propellers of boats. The smaller marinas on state lands are being worked with. 

The chemical they are planning to use is less toxic with a quick dissipation.  It is non toxic to fish and  within a matter of hours it is undetectable.   The chemical treatment is expensive at $1500 an acre and they are trying to spray 30 to 40 acres.  Combs is working with other departments to be able to get to it fast, and he is  trying to raise $100,000.

They will do public notices, they will try to spray in evening after the recreational use. Eurasian Water Milfoil is a rooted, submerged aquatic plant. The leaves appear green while the stems are white to reddish.

Leaves are feather-like, with four leaves arranged in a whorl (radiating out from a single point) around the stem. Space between whorls along the stem can be a half inch or greater. Each leaf has a central axis with 12 to 21 leaflet pairs. Leaflets are limp when the plant is removed from the water. The stem is typically light brown, but sometimes pink. Tips of the plant are sometimes red or pink in color. Color alone should not be used for identification as it can be highly variable.

A small pink flower spike up to four inches long produces tiny yellow flowers. Male and female flowers are found on the same plant.   Even though each plant can produce approximately 100 seeds per season, this species is more successful at reproducing via fragments.