Q.We Have A Large 20 Yr Old Pecan Tree (southern Ohio) Producing Pecans With No Nutmeat.
The large tree has a mate,(about 15 ft. from the large tree) but the smaller tree, also 20 years old, doesn’t produce nuts at all. Both trees drop hundreds and hundreds of flowers in the spring and squirrels plant the empty nuts all over the yard. What is lacking causing this deficit?

Certified GKH Gardening Expert
Insect and disease damage is most often the reason nuts don't fill. Nut trees need a regular fertilizing schedule and insect and disease management. These articles should help. You may want to contact your local extension agent for publications pertinent to Ohio.
https://lee.ces.ncsu.edu/2015/10/reasons-pecans-dont-produce/