Filbert trees - disease?

I have 5 established filberts on the new property I’ve moved to, and they appear to have brown spot (per an ID/care app). One has gone downhill really fast, and it’s been spreading to the others. I did remove most affected leaves a while back (and cleaned pruners with rubbing alcohol before doing each tree). I sprayed the leaves with a baking soda solution, as recommended by the app. They just look awful. They do have loads of nuts growing on them. I’m worried the one won’t make it to next season, and I’m not sure the best way to help them all. What I’ve done so far doesn’t seem to be helping.

I should add - I’m starting with a typical manicured yard and the soil is all clay. Zone 6, and it’s been hot and very wet since I moved in. The previous owners have covered all of these types of areas around trees and shrubs with garden cover cloth, strips of plastic, etc, and then covered that with mulch, and then neglected it all for a couple of years. I am pulling up the cloth and plastic bit by bit to do sheet mulching instead. Then I plan to plant more natives around these trees to make a sort of guild for them. I really wish they weren’t so close together but there’s not really anything I can do. I suppose if they really don’t recover well, I could pull a couple of the worst ones out so the others can have more of a guild around them.


Any suggestions to help these poor trees get through this season are welcome!

Eastern filbert blight is a common disease of European hazelnut stock....I would start there.  Here is a link to the disease description from the University of Wisconsin.  https://hort.extension.wisc.edu/articles/eastern-filbert-blight/

You may be able to find a description from the University extension office in the state in which you live.  Good luck!