Yah, I think I've narrowed most of the issue in my yard down to proximity to the lake. The two malikas that were within a few dozen yards of the lake (both my property and a neighbor's) succumbed to fungal infection. I was able to bring mine back to life with copper + sulfur, but the neighbor's croaked due to non treatment.
Same goes for my keitt. The other heitts in the neighborhood that are 100+ yards or more from the lake have no issue with fungus. Five out of 8 or so mango trees around the lake have all died from fungal infection. Glenn and Edward are both thriving within a few feet of the lake, and a NDM is hanging on, but the rest slowly croaked within a period of about 2 years after having been successfully established. These trees were wide open and fully exposed to the breeze and with zero shrubbery / weeds nearby and in various locations around the lake, so the lake is the only conceivable factor.
The lake causes a heavy dew to settle on most plants from dawn until the next day. Even plants that you wouldn't think were susceptible to fungal issues (eg, jaboticaba, persimmon, and even jackfruit) are affected. Now that I've picked up a treatment regimen, things have been getting better.
The mallika that I have at the southern edge of the south lot (about 80 yards from the lake) is doing well.
Mallika does very well in my yard when it comes to disease resistance. I got more than 50 mangoes last year; excellent fruit and a nice size as well. This year, it won't set as many fruit (many spikes with nothing on them, a bit like carrie in that sense) but I haven't seen powdery mildew or anthracnose on it at all. Same goes for Keitt.
Some of the Carrie and Lemon Meringue mangoes are showing signs of anthracnose. Never seen that before.