Black Walnut

[8Mud]

I have what seems to be a fifty year old Black Walnut tree. My best info is that it was planted around 1953. The tree is healthy, seems vigorous enough. The soil around the root ring has been regularly supplemented with compost. I stopped using nitrates some years ago as the soil was turning acidic, I occasionally spread some Beech ash, lightly.
The tree refuses to flower, sometimes flowers a little, the last good yield was four years ago.
Many of the possible pollinators in surrounding gardens have been felled as they have outgrown the gardens, though there are Oak and some other possible pollinators in the area.
My thoughts are that maybe the traditional weather patterns have been disrupted, we have had warm, early springs, that may encourage early buds and then relatively severe late frosts. Many of my fruit trees (Plum and Apricot) have also had a low yield, though the Apples seem OK.
Possibly a soil problem or the tree is just too old?
Pollination doesn't seem to be an issue, lack of blooms completely seems to be the problem (or possibly frozen buds).
The tree has always (last twenty five years) seemed to by cyclic in it's yield. When it does have a good yield it is a very good yield 2-300 lbs. of delicious nuts.
Any ideas?

[bullthistle]

You could try testing the soil. Apples shouldn't be affected as much as plums or apricots with late frosts but you could try some water spray on the smaller trees when you get a late frost.

[8Mud]

I may have answered my own question, while reading another thread about a nieghbor spraying a board members hedge. It jogged my memory.
Behind my garden is a parking lot, made of porous cement paving stones. I noticed the owner spreading some sort of herbicide on the parking lot, it looked crystalline, kind of like salt (but this was spring). His parking lot is 18 inches higher than my garden. The trouble with my nut tree not producing (or producing very poorly) started at about the same time (that fall) when he started using the herbicide.
Which sure makes me wonder about the nuts I've eaten since.
Most of my good producers, berries and fruits are either above grade ( I grow a lot in raised beds) or farther away from the parking lot than my Nut tree and my also poor producing Plum and Apricot.