A long way off, but I have fungicide questions for my large pear trees?

Derek Reese 29

5 year old buck +
Hello everyone,
I have 9 very large (30-40 foot tall) pear trees (possibly an Asian variety) in my front field. I also have 2 pear trees (Kieffer and a Buerre D'Anjou) that I planted near the existing tall pears in the spring of 2021.
The larger trees all are not doing great (some dying limbs, losing some bark) and all have black dots on the leaves (I have surmised that it is either some kind of leaf spot or scab, but I am not sure).
This year we had a pretty bad drought in the middle of the summer and the leaves fell early, as did the limited amount of fruit (last year there were 1000s of pears when we had a wetter summer).
I also noticed the same thing on my new Kieffer pear (it is around 12' tall). I think the drought may have only hurt the trees.
I have a few crabs planted in and around these pears, so I do not want my newer plantings to be affected by a disease or fungus from the older, weaker trees (they are all DR trees, but still).
Is there a product I can use on the larger trees that is not a spray, as spraying these trees is out of the question due to their height?
I am looking for something like a soil drench that anyone may have experience with? Thanks in advance!
I intend to fertilize the trees this spring.
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