More than likely, yes. The overwhelming amount of fruit trees will need two of the same variety of trees to produce fruit. You will need to purchase at least two different varieties of the same type of tree. You will need two apple trees, two pear trees, two sweet cherry trees, and probably two plum trees. Peach trees, most blueberries, pie cherries, and grape vines are self fertile and do not need a pollinator. However, even with self fertile trees, you will get more, larger, and better fruit if there is a pollinator nearby.