Cheap insecticide a little while back we had an infestation of nematodes they caused little potato like enlargements on the roots of a lot of the plants. I got a pale of water put in two pieces of copper tube and connected to a car battery after about 1-2 hours the water was blue. I applied this to the plants and ground and fix the problem. Copper is poison for invertebrates and it is an essential mineral for man.
This is the first time I've heard of nematodes which sounds a scientific name of an organism. The process you did was like electroplating minus the H2So4 (sulfuric acid) that would make the water an electrolyte. But running an electric current in the water tends to melt a part of the pole, i.e. the copper wire would mix in the water. You have therefore created a chemical compound with that chemical reaction. Huh, deep science. PS. I could have added more but my internet access is very slow.
I produced what they call a colloidal copper solution. Much the same way they make colloidal silver which I have also used in some squash that was diseased and it worked like magic.