Milfoil project starting soon

SANDPOINT — A federally funded project to nail down the most effective herbicide application methods for treating Eurasian milfoil in areas with deep water and water exchange starts next week.

The project will get under way starting Monday in the Gypsy Bay and Morton Slough areas of the Pend Oreille River. Two 10-acre sites will be treated with Renovate OTF, a granular aquatic herbicide containing the active ingredient triclopyr, and Rhodamine water-tracing dye.

The test plots are off shore, so water use restrictions for nearby landowners are not anticipated.

TetraTech Inc. has received funding from the U.S. Army Corps of Engineers Research & Development Center to conduct the study in conjunction with herbicide applicator AquaTechnex and the SePRO Corp., Renovate OTF’s manufacturer.

AquaTechnex’s Eurasian milfoil control blog said surveys conducted this summer indicate that most of the areas treated between 2006 and 2009 are either milfoil-free or infestations were reduced enough to enable use of the waterway.

“The milfoil that remains is largely in deep areas of the lake and river with significant water exchange. The efficacy of aquatic herbicides is a function of them remaining in contact with the target vegetation enough to receive the proper dose.

“Factors such as dilution, currents and drift can affect efficacy,” AquaTechnex said in an Aug. 12 blog post.

Next week’s work will focus on understanding those factors in greater detail. The objective is to compare contact and exposure time relationships with granular and liquid herbicides in difficult-to-treat areas.

The project also involves the use of acoustic Doppler current profiling to compare data to herbicide dissipation, according to AquaTechnex.

• Information: http://pomilfoil.wordpress.com