Bill,
Some 'precocious' varieties may begin bearing in as few as 4-6 years after being grafted, while others may require as much as 8-10(or more).
Grafting onto seedling rootstocks, it's probably scion variety that exerts most effect in time to bearing.
However, if you graft scions into a mature, bearing-age tree, it may 'force' earlier fruiting - this is a phenomenon that the fruit/nut breeding folks routinely employ in order to get an earlier take on the characteristics of seedling resulting from a planned mating.

Growing out seedling pecans to bearing age may require 12-20 years or more. I have several hundred seedling pecans(offspring of Major & Posey) planted in a CRP bufferstrip here on the farm - planted the nuts in 1998, transplanted 2-yr seedlings in 2000; many are 15-20 ft tall, but no nuts yet. Black walnuts planted at the same time have been producing for 4-5 years.

Lucky p.,

I have a few bearing age pecan trees growing at an old farm place. They do not produce much as they have been neglected for years. What can I expect from a scion of a precocious type that is grafted onto one of these older trees? Some are 6 inches thick at 7 feet and some are larger, some smaller.
Bill

Lucky,

I have a pecan that's 4 yrs. old, as I recall. I moved it to a different location last Spring (2011). This year I noticed it developed catkins. Is this normal?

The tree is still very small because of all the moving.

I really have no experience with intentionally 'pushing' production by grafting into mature trees - only know that that's how the plant breeders speed up time to bearing with seedling selections so that they can assess fruit/nut quality.
I don't know if grafting into senescent tree wil gain you much ground, but perhaps if you do some rejuvenative pruning, or just fertilize appropriately...it might help.

Olpea, catkin production - and possible fruiting - in your tree's case may be a response to stress associated with the move. Sometimes, when trees are damaged or stressed, to a point where they 'think' they're in danger of dying, they'll make a 'last ditch' effort to reproduce. Not saying your tree is going to die, but it is a biological entity, and there may be some chemical messengers produced that induce it to procreate, just in case...

"just fertilize appropriately...it might help."

What kind of fertilizer and when? I have been putting plain old 10-10-10 on mine 3 times a year. As recommended by a local pecan grower, March, May, and July.

I've got a 12 year old tree, forgot the variety, supposed to bear in 7 years, the best I remember. It is only about 12' tall, no catkin production yet. A 7 year old tree that the graft died and the rootstock is growing, it is about 12' tall also.

i dont understand.. how fertilizing.. or feeding a tree ..

will speed it along to sexual maturity ... which fruiting/nutting would be ...

its either sexually mature or it isnt ...

if i feed my 10 year old more food.. he isnt going to reach sexual maturity faster.. what difference would it make with a tree???

ken