Question
Hi, William,
I have a pecan tree in the yard. it is about 30 years old. and 40 feet tall. It looks good and provides shade. but it does not give fruits. any thing I can do?
Thank you.
Jack

Answer
Hi there. Being a NJ tree man this is out of my area but here is some info I found.
Growing Pecan Trees-A Homeowners Guide To Pecan Tree Care
When one stumbles across a website such as this, an entire database devoted to the art of growing pecan trees, he/she might draw the conclusion that growing a pecan tree must indeed be one of the most difficult and complicated chores on earh.  I assure you it is not true.  Pecan trees have survived and thrived throughout Texas and the southern United States for...well, who knows.  Pecans were a mainstay diet for our Native American Indians (I hope I'm politically correct there.)
It is important to note that pecan trees thrived for centuries without special atention only when conditions were right for their survival.  The same will hold true with a pecan tree that you plant on your property, or one that you perhaps inherit with the purchase of your property.  They aren't the type of tree that you can just ingore like you can that Mulberry tree in your back yard, that, as you are sitting here reading this, is taking matters into its own hands and firmly planting its massive root system into your sewer pipe.
Pecan trees do indeed have a feeder root system that extends underground about as far as it's overhead canopy of leaves.  While these feeder roots do draw in water and nutrients,  what will ultimately lead to the success or failure of your pecan tree is how successful its massive tap root is in acquiring a substantial source of water from deep within the ground.
So, rule number one in successfully growing a pecan tree is providing water for it.  Raining on your tree, for the most part, doesn't count.  A newly planted pecan tree during its first growing season will typically need a gallon of water a day.  That means every day, not Monday, Wednesday, Friday, or gee...I forgot.  This doesn't mean you have  to water every day.  It does mean that when you water, be it every seven days, you need to water deeply so the feeder roots can search out and find moisture.  And for the most part, the sprinkler watering your lawn will not provide sufficient water for your pecan tree.
If you have a mature tree in your yard, it will need between 100 to 250 gallons of water per day during the hotttest part of summer, if it is to provide you with a crop of pecans.  When a pecan tree begins to stress, whether it be from lack of water, an insect infestation, or disease, the first line of defense is to turn loose of it's crop of nuts.
So, if you haven'tbeen paying attention so far, Thou shalt water thy pecan tree.
With sufficient water and nothing else, a pecan tree wil survive.  However if you don't do anything else, such as pruning, your tree will become nothing more than a pecan bush.  Pecan trees are lazy trees and prefer to grow their branches close to the ground.  It takes less energy to grow a branch two feet from the ground than it does way up high.  There are no hard rules in pruning and you really can't go wrong unless you just go wild and cut all the branches off your tree.  Keep your branches trimmed to the height of you head, or the height of the tallest member in your family.  It's that simple.  Every spring, your tree will try to be lazy and pop little shoots out all around its trunk.  Just pinch them off.
There are some problems you may encounter.  Insects (bugs) can cause considerable damage if not controlled properly.  Part of our pecan orchard management program is to NOT just go around hap-hazardly spraying pesticides 'just because.'  There are entire seasons that we do not spray our trees.  This should be your policy, also.  Spray  only when needed, using the least amount necessary to get the job done.  If you have a newly planted tree, it is very important to contol aphids and other bugs that may 'eat your leaves'...no leaves, no tree.
You can treat most of your insect problems with the usual 'over-the-counter' sprays found at your local home and garden center.  The most common problem associated with pecan pests is that sticky 'syrup' that just floats through the air and coats your car windshield and everything else.  This is caused by aphids, or as the nut gurus have discovered, is a result of Aphids uh...pooping on the leaves of your tree and tiny Micro-organisms feeding on uh...IT, which since IT is on the leaves, result in leaf damage and the resulting 'floating syrup.'  To clear up his problem, simply spray your tree (or your neighbors) with an over-the-counter spray that claims to control Aphids.
Your pecan tree need Zinc and I personally think that it is almost as important as water for your tree.  Signs of zinc deficiency are pale green leaves, bare branches with a cluster of small pale leaves at its tip, and dead branches in the tops of your trees.  A lack of zinc also prevents nuts from filling out.  Zinc is available at most garden centers, either in a liquid or powder form.  You should spray the foilage on your trees with a zinc spray three to four times early in the growing season, beginning with leaf bud in spring and regularly every three weeks or so into mid-June.  Do not spray zinc during the heat of the day, as it could cause leaf burn.
Fertilizing your pecan tree is necessary to ensure growth and nut production.  Ammonium Sulfate is a common nitrogen fertilizer for pecan trees and is readily available at home and garden centers.  While the 'nut gurus' have a whole book of formulas and theories concerning pecan tree fertilization, it is usually accepted that for each inch in diameter of tree trunk (a foot above the soil) you should apply one pound of fertilizer.  If you don't want to rummage around the sewing box for your wife's measuring tape, you can also apply one pound of fertilizer for each year of your trees age.  You should apply fertilizer twice during the growing season, once at mid-March and again in mid-May.  So, if you determine you need to apply ten pounds of fertilizer (because your tree is ten inches in diameter or ten years old) you would make two applications of five pounds each.  Apply evenly underneath the entire canopy of the tree.  I recommend that you water your tree deeply prior to application, then water only lightly to dissolve the fertilizer just beneath the soil.  This allows the feeder roots access to the nitrogen over a longer period of time.
These tips are just a generalization on proper pecan tree care.  For more in-depth and detailed articles on growing pecan trees, be sure to visit our other sections.