Swen,

Did you use Cutrine Plus or Ultra? Ultra has a surfactant/penetrant called CideKick that I've seen frogs be sensitive to in high concentrations. Also, both products have a Ethanolamine in them that chealates the copper. This Ethanolamine might have negatively affected your frogs. However, I have never seen Cutrine Plus harm frogs, but I have seen an application with too much CideKick affect frogs.

Also, your method of application could have much to do with the negative effect to your frogs. If you were applying from a sprayer, using a high concentration, either from shore or boat, that may have done it. It's best to apply Cutrine or copper products to algae using a high volume/low pressure sprayer that slowly injects the product. This will allow better algae mat mixing, lower concentration of product out of the sprayer nozzle and less direct contact with frogs and their eggs.

Most of the time when we hear about do-it-yourself applications going wrong - it's not becuase someone used the wrong product at the wrong rate, rather they applied it incorrectly and with the wrong type of equipment.

Don't be discouraged by using the Cutrine product. It is a much safer and less toxic form of copper than copper sulfate. Copper sulfate participates out of solution in 24 hours and accumulates in the substrate 20 times more than Cutrine and other chealated copper products.

Cheers,

Trent