The dieback you describe might have been due to an infection like Botryosphaeria canker, a fungal disease that takes advantage of trees and shrubs stressed by drought and other environmental conditions. Unless you were watering the tree periodically, that may be a likely reason for the damage. We can't rule out anthracnose, but it's not as common a disease on dogwoods as it was a couple of decades or more ago.

Do not apply any more fungicide like the Garden Phos without confirmation that one of the diseases that product controls (root rots, essentially) is responsible for damage, as it could also harm other soil microbes that benefit root health. Fungicides also cannot cure existing disease; they can only help to discourage the infection of healthy tissues, and treating the root system of a tree with root rot (or any other soil-borne infection) usually is not successful or worth the expense since it can't reverse any dieback that already occurred. The symptoms you describe don't sound like those of root rot, but it's hard to say without photos of the state of the tree before you removed the dead/dying leaves.

Do remove landscape fabric at any point you're able to take it out, and definitely monitor the tree for watering needs; we're still in a notable drought, and while dogwoods are intolerant of soils that don't drain well and hold too much water, they're also not very tolerant of prolonged drought.

Miri

Hi Miri. Thank you for your answers. May I please attach photos?

You'll see arial overview that shows all three levels of issue - bare branches, small-leaved branches, and normal-looking branches; the "anthracnose" can also be seen if you zoom in. 

NOPE! Only let me attach 3 .jpgs

In addition, you'll see:
- a few labeled closeups of anthracnose (?) as well
- trunk and root issues
- the green outer layer of twigs with small-leaves
- the miserable fabric removal adventure

I no longer live in MD, as I stated on the form. I've since moved to VA. And this dogwood is in Richmond, VA. But I hope you can still help me know how to care for the tree.

For fun, when my kids were young, I led the Bond Mill Elementary PTA committee that won a PG County Landscape Beautification award; and while attending U MD for my Nutrition degree, I sat on your lawn to study many hours and under your auspice, even co-developed and conducted a Coop Ext. 4-part series called A Banquet From Nature! 

Thank you so very much,  
Karen Widmer

Hi Miri, will send other photos in subsequent replies.

Karen

Hi Miri.

Anthracnose here :)

Hi Miri,

More...

We can't zoom in, unfortunately, as the images are small; attaching files at least 1MB in size (each) is best so we can examine them more closely. From what we can see, the bare branches show extensive dieback and all of them need to be pruned off. Any areas with smaller-than-normal leaves should also be pruned off, as their stunted nature suggests that the branch is too weak to recover and may be in the process of succumbing to infection (or whatever the initial type of damage was). Make sure you remove all dead wood, since we see what looks like a long section of unbranched main stem where the bark looks cracked and the wood dead.

We can't see clearly the symptoms labeled "anthracnose" in the photos due to darker lighting and the small images, but since dogwood anthracnose causes progressive dieback where leaves wilt first and then defoliate, the pattern of dieback in the other photos doesn't look right for anthracnose. In either case, the recourse would be the same, though -- pruning out any damage since it can be cured with fungicide. Any leaf browning may be scorch, though, from insufficient root moisture, or possibly fungal leaf spot that isn't as overall health-threatening as anthracnose.

Since you're in Virginia now, we recommend that you connect with your state's Extension services for future questions, so they will be better acquainted with your local growing conditions.

Miri