Last month one of my 3-year old Meyer Lemon trees had an amazing bloom of flowers. Hundreds. The bees loved it. However, I do not see any fruit developing. It appears that the flowers all dropped without setting fruit. Is this common? What is the cause?

Last year this tree bore a few fruit, so I was optimistic that it would set abundant fruit this year.

John

How much water was available to the tree roots at the time the flowers were full? Should be a minimum of 60% of soil saturation, for a good set. - Milet

Well, their are other reasons but the number one reason for citrus flowers not to set, is the lack of sufficient moisture available to the tree at the time of flowering. Remember, under any or all conditions, only about 1 to 3 percent of the citrus flowers on a tree ever produce fruit. If all flowers produced a fruit the tree would be crushed under its own weight. -Milllet

Could fertilizer have caused the flower drop and lack of fruit? I had broadcast some NPK (13-13-21) on the ground in the dry season, and the same rain that activated the blooms also liquefied the NPK making it available to the tree. I am wondering now if the fertilizer caused the tree to shift from reproduction to vegetative growth.

It wasn't over-fertilized.

The fertilizer element nitrogen, and to some extent potassium, applied prior to flowering is a common practice used by growers to promote a good flowering in citrus. - Millet

extra nitrogen while flowering cause flower droping. As Millet said, you should fertilize prior to flowering. I know this from my own (not big) experience.