(Orleans)– The discovery of Eurasian Watermilfoil last year in the lower chain of the Iowa Great Lakes resulted in stepped up efforts to snuff out the invasive weed before it could spread to other lakes in the chain, such as West Lake Okoboji and Big Spirit Lake. A new tool, a herbicide called Sonar, which is also effective against curly leaf pond weed, was added to the arsenal. Mike Hawkins, a fisheries biologist with the Iowa Department of Natural Resources, says multiple treatments of the herbicide were made throughout the fall and winter and will continue into April on East Lake Okoboji and the lower chain. He says testing done last fall on the north side of East Lake Okoboji indicated Sonar was 95 percent effective at killing curly leaf pond weed. He says while the herbicide is very effective at eliminating eurasian watermilfoil on a long term basis, its effect on curly leaf pond weed is only temporary. He says that will be especially noticeable this year…
“This coming year we hope to see very little curly leaf pond weed, a very good control on that, and then we’ll be monitoring very, very closely for eurasian watermilfoil to see if we’ve actually knocked that completely out. We did a large application of the herbicide, 2,300 acres of water was treated. It only takes a few gallons of this herbicide to actually treat for that for those two plants. And again, this herbicide that we’re using does not and will not affect the native plant community so I think there’s been a little bit of concern that we’re treating all of the plants because folks do understand how important plants are for the Iowa Great Lakes for water quality, for the health of the fishery, and the aquatic community, but we’re only treating those two invasive plants with the treatment, which is pretty unique and it’s one of the first times that we’ve been able to do that in the midwest and one of the largest treatments like its type anywhere in the country.”
Hawkins says it will result in a change this spring in the curly leaf pond weed management strategies that have been used in the past…
“As far as our spring treatment plan that we had normally been doing up on the north end of East Okoboji and actually down into Lower Gar, we don’t think we’re going to have to do that this year. That would include harvesting and application of aquathol for the curly leaf, so we think we’re going to get good control there. I think it’s a little bit confusing for folks because there are native plants that come on later in the season, later in the summer, and start to grow and for some folks that can mean some harvesting around docks just to maintain access. But again, those are native plants, they are not the invasive type.”
Hawkins adds crews will be monitoring the lakes extensively throughout the upcoming summer and into the fall for any signs of eurasian watermilfoil…
“This is a kind of a one time shot at eurasian watermilfoil before it spreads further into Spirit Lake and West Okoboji, and so we’re very hopeful and the community was on board with this as well, in helping fund this project, but very helpful that we can get it knocked out. It’s going to take a lot of monitoring to know if we did. So we’ll be looking throughout the summer and into this coming fall and next year as well to see if we actually were successful. So it’s going to a waiting game at this point.”
Hawkins notes that there no restrictions for lake use with Sonar, saying it’s safe for recreation and all other activities on the water.
