Just a note to add.

Both black cherry and choke cherry grow wild here. Can they be used as rootstocks for apricot?

Redpine:

Your pears might have had fireblight and crown rot of some type might be a possibility with apricot. All that other stuff is unlikely.

In zone 4 cold is a real danger for apricot. But wet soil is the most likely cause of your problems especially with apricot.

You need to do something to assure drier soil. Making a large raised bed either for each tree or as a row is one viable option. Tile drains are another option. Both would be great. Beds need to be about 18 inches high and 10ft or so wide as a minimum if your soil is as wet as you indicate.

The only disease you can inoculate against before planting is crown gall. That is not your problem.

There are no rootstocks that will solve a really bad water problem.

Fruitnut seems right on it to me, as usual.

I would ask who it was that gave you such a broad and unlikely diagnosis. Very often when you try to get info from a nursery someone will just spread the BS so you feel you've been serviced. Tradesmen self-titled as arborists or landscapers have been occasionally known to do same.

I think zone 4 might be a bit iffy for apricots unless you give them some extra protection. They do not like wet feet, so I agree with fruitnut.

Apricots and peaches also do not like to get their leaves wet too often. They seem to have an endless lists of fungal diseases that just need a bit of damp to grow.

Pears shouldn't have any problem with zone 4 and you could probably find a root stock and variety of pear that would be more tolerant of wet conditions, especially if you plant them in raised beds, as advised.

Really, you are going to have to get an accurate identification of what diseases your trees are getting, because you can put the trees onto spray programs that will help control a lot of diseases.

Also, only buy from reputable nurseries. Check garden watchdog before doing business with any nursery. I suggest that you do not buy trees from the big box stores.

I agree with what's been said so far.

But for us to be more precise, it would be helpful to know what occurred to the trees before they died. Leaf problems? Never leafed out? or what?

Also how you planted them? What "special" things you did to the soil or planting hole.

Then there's the follow-up care.

Z4 is pushing the edge with conventional apricots. I was assuming you were trying to grow the extremely cold hardy varieties like Scout.

As far as comments about peaches and cots not wanting their leaves wet too often, I don't feel that's an issue- it's the fruit that can rot from lots of wetting. If you grow peaches with reasonable leaf spot resistance survival should not be affected by being in a humid climate and the same goes for cots.

Cots are often killed by fluctuations from warm to sub-freezing temps in winter and spring. Z4 is borderline for most pears as well, so maybe it's temps that are killing both. Poor drainage will contribute to this kind of kill.

When I bought this property it had a "family" orchard of 20 standard fruit trees. Six of them were inappropriate for the climate or site and I removed them. I see no reason to waste time, growing space and labor on trees that will never fruit with usable fruit. Al