My Grapefruit Tree is producing smaller fruit lately and I would like to know if it is a fertilizer or watering problem?

Question

Older, mature tree in Sun City AZ, which usually provides an abundance of large, sweeter grapefruit in normal conditions.

Answer 1

If the tree doesn't get fertilized once per month, then this will be the most likely case. This article will give you more information on why a grapefruit can fail to fruit properly: https://www.gardeningknowhow.com/edible/fruits/grapefruit/grapefruit-tree-not-producing.htm