Aquatic Herbicide Simulation Trials Help Understand Efficacy

Aquatechnex biologists applying Rhodamine WT dye to simulate aquatic herbicide applicationOne of the keys to controlling noxious and invasive aquatic weed species with aquatic herbicides is understanding how water exchange within the treatment sites might affect performance of the product.  In the mid to late 1980’s US Army Corps of Engineers Aquatic Plant Management Researchers started to think about how these products update within target weeds, how much time the target weeds need to be exposed to the particular herbicide and how water exchange impacts efficacy.  This research has lead to operational improvements in using these technologies to impact invasive aquatic species and to help operational aquatic plant managers plan treatments.

Aquatechnex through contracts to support this research were along for the ride during these discoveries.  Once the federal scientists understood the requirements for the various aquatic Hebrides, they turned their focus to learning in the field what was actually happening within these aquatic plant communities with respect to water exchange.  Our team was also hired to support that research throughout the 1990’s.  The result was a predictive tool that uses Rhodamine WT dye in the role of an aquatic herbicide.  This dye can be applied at a known concentration, and it can be measured with an instrument called a flurometer.  Sampling grids can then be set up within the treatment plot to monitor how long the dye remains and at what concentrations.  Sampling stations outside the plot can be set up to see where a potential herbicide might go and at what concentrations.  Very useful tools when questions arise about potential restrictions on water use from intakes.

This summer our team is deploying this technology to study a number of sites in North Idaho Large Lake systems to help improve Eurasian Milfoil Control Programs and minimize the amount of aquatic herbicide necessary to deliver effective control.  This research work under operational conditions will help plan future treatment programs on these systems to both deliver selective control of Eurasian Milfoil and to minimize costs to the various agencies that require this work.


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