The only info I can give is that a large pecan tree borders my property. I believe it is a wild one and was not planted by anyone. Every year the harvest is different. Some years there are lots of nuts, some years none. Some years they are big with thin shells (easy to clean), some years they are small and thick shelled. I guess the farms that grow them commercially have it all figured out, so they get a consistent harvest but I don't know what the secret is.

(Laughing, sorry!)

Not sure if pecan trees follow this same pattern, but I do know that some trees follow a 2 year plan where they produce more heavily one year and lighter the next year. Also, the weather during prior months can have a lot to do with your harvest. If you had the right weather and optimal rainfall 6 months or 9 months ago, it will encourage your trees to produce more at harvest. Even just one days worth of bad weather at the wrong time can affect the harvest, for example, a late frost ruining fruit formation.

Thanks to all who have replied. I thought maybe it was a cyclical thing, too, but the tree with the tiny nuts has produced quite a few nuts, but small, for the last 3 years. I can't figure it out! I just hope the larger nutted one starts producing more. Thanks again!

wonder if there's some confused (not crossed) pollinating going on that is reducing your production of the regular sized nuts.

Most likely the tree with small nuts grew from a nut or was a grafted tree and the graft died.

Most of the big nut trees are grafts.

Do you see a lot of "blooms" in the spring on the one that doesn't produce? If you have a lot of blooms but not many nuts it's a pollination problem.

However the small nut tree should be a good pollinator for it.

You did fertilize them too late, in zone 8 early March with 13-13-13 with zinc and you may need to add lime.

Something that the "oldtimers" used to do to improve crops was to use Red Devil Lye on them. Drain cleaner! Crystal Draino will work, do not use liquid.

They would sprinkle it around it at the drip line, edge of the tree limbs in the fall. It it seemed to work, but most people nowadays's do not recommend it!

If you try it be sure to put your kids and pets up before doing it!

You will need to water very good or wait until a rainy day to do it before letting the kids and pets back outside!

Here is a link that might be useful: Pecan Blooms