Hi kardak
Milky spore is very safe and will only hurt the grubs. It is a bit expensive and I'm not sure it will be easy to get in your location.
I noticed you have mentioned vinegar a couple times. Yes, wine does sometimes turn into vinegar. But it is a process where a specific bacteria (or protein, I don't know) manages to get into the wine and that bacteria starts a slow conversion process. Fruit flies are the usual pests that introduce the bacteria into wine.
Young wine, especially young non backsweetened wines, have a sharp fairly unpleasant taste. I personally believe it is malic acid, and that the acid bite seems to soften on it's own at about 1 year of age. At least my fruit wines go thru a massive change in taste at 1 yr old.
I suggest you actually spend a few minutes smelling some vinegar, and if you are brave, taste it. There is a huge diff between vinegar and new sharp wine. New wine will improve if given time. Infected wine will turn to vinegar over time.
I believe the reason you like the wild yeast wine better is that that wine has not converted as much sugar to alcohol yet, so it still tastes sweet to you.
BTW some things I keep very far way from my wine making area are actual vinegar, chlorine bleach, and non wine yeast. They can all interfere with good winemaking.
Hope your tree recovers. I know the pain.
Pam in cinti