Question
I have 2 apple trees that are about 10 years old that are planted about 10 feet from each other in a semi-shaded area. They are now about 12 feet high and 4 ft. in circumference. They flowered and bore fruit the the 2nd and 3rd year but not since. What can I do to improve the flowering?

Answer
Hi Mike,
Thanx for your question.  There are a number of reasons why your apple trees haven't set fruit.

1.  High nitrogen fertilzers such as lawn fertilizers promote heavy green growth at the expense of flowers and fruit.  Use fertilizers rated for fruit trees.
2.  Too many weeds or grass beneath the tree competing for water and nutrients.  Keep the areas around the fruit trees mowed or mulched, watered and free from weeds and unruly growth.  Don't allow suckers to grow from the root stock.
3.  Late freezes or cold spells.  This is a frequent cause of a fruit tree's failure to bloom.  Many times the cherry, apricot and peach crops fail when the wrong cultivars are planted in areas too far north.  While the tree survives and thrives the flowers or flower buds are continuously subjected to late freezes or cold spells and die and drop off, resulting in no fruit.
4.  Not enough natural pollinators.  Many parts of the U.S. have experienced pollination due to the collapse of native and domesticated beehives.  Many apple trees need another pollinator such as another apple tree or a crabapple provided the blooming times coincide.

I hope this helps.  If you need more information.  We have a fruit tree expert on Allexperts, Nick McCann.  You can access Nick at Home/Garden and then click on Gardening and then click on fruit.
Tom