Hi Maureen,

Thanks for contacting UNH Extension about your Holly.  It's very important to identify the exact problem and that can be difficult.  I applaud you wanting to use something non-toxic.  I'm attaching some helpful articles and fact sheets from UNH and other extension services, some of which you may have already found and used to help you try to identify the issue.

https://extension.psu.edu/holly-diseases        https://hgic.clemson.edu/factsheet/holly-diseases-insect-pests/                   https://content.ces.ncsu.edu/insect-and-related-pests-of-shrubs/pests-of-holly

Normally, I would suggest you send a sample of the bush/tree trouble spots to a UNH lab focusing on plant and pest ID but unfortunately it is temporarily closed.  However, I'm wondering about your soil since it's happening in the same area...it might be good to get a soil test:  https://extension.unh.edu/agriculture-gardens/pest-disease-growing-tools/soil-testing-services  Part way down the website, on the right, are several blue words you can push for more detailed info along with the form itself.  

Once you have a better sense of what exactly the issue is or might be...I would search online- paying closest attention to University and Extension websites which have research behind them and no commercial motives- pollinator friendly herbicides, pesticides and fungicides.  Your local garden center that is pollinator friendly also, might have some recommendations as well.  If you find something you feel ok about, make sure to read and follow all the instructions on the back to the T to protect yourselves, the soil and surrounding plants and animals.  Perhaps start small too to see if it helps.  

I found at least one resource on dead leaves though I'm not sure it will be helfpul.  It mostly says that if leaves are dying, branches might not be.  You have certainly described a more challenging issue with the leaf fall, curl etc. https://extension.unh.edu/blog/2018/02/how-can-i-help-my-holly-bush-brown-leaves-dead-branches-it  However, one other thought.... last year was a hard year for other shrubs too, for instance Lilac.  (I can't tell you how many questions we received on that.) Perhaps this year things might improve again for your Hollies, given this is only one year...  I'll cross my fingers for you.

Best,
Catherine