Okay pardon me for being skeptical but this doesn't seem right. First of all you join here and immediately post about your project. I would be a lot more suspicious if you were selling the machine, but you're not, so you earned enough credibility points for me to take you more seriously
Traditionally electrically treated water has never been shown to do anything for anyone, anywhere. However your post prompted me to look for patents. Sure enough back in 1993 and 1995 the Japanese patented the device you have made. The purpose was to produce acid water for disinfecting hospital instruments. This is different from anything I've seen. With that in mind, do you mind answering a few more questions?
1. How much could a rig like that be made for?
2. It looks like you have water supplied to both sides of the electrolyzer. I'm not sure why you would need that because the water needs to flow from one side to the other. What kind of membrane do you use to allow the ions to flow?
3. What kind of salt do you use? The type of salt might have a great deal to do with whether you get more acid water or alkaline water.
On to some practical matters. Vinegar (pH of 3.0) is an acid used in organic gardening to kill plants. The claim for your water is a pH of 2.0. I'm wondering why all it kills is the fungus.
Secondly I'm concerned that the water is, as it was stated, killing "germs." Those germs are not all bad germs. Most of them are beneficial. I'm wondering about the mechanism with which it might be killing the disease from your trees.
I'm going to send your link to some friends in the soil biochemistry biz so get other thoughts. I hope you are on to something here!!!