They tend to show up in shaded places or edges of fields. They also don't seem to be long lived. Areas where we have them, the trees will reach typical heights then die off there and begin to show up in another spot. More mature trees have a deep red blossom that comes in early spring. Tough to beat the critters to the fruits, not that I like them. You can pick them somewhat green and wrap in newspapers like pears are done for later use. I used to take them from KS to KY for my Wife's granny that way.
Kentucky State University developed improved an version for commercial use a few years back. I think it was done via collection/selection.