hand pollination will increase yield. By definition, however, grapefruit trees are self-pollinating.
Nectarines are self-fruitful (self-pollinators)
you need to say what tree you are asking about.
yes
An apple, a flower, a banana, and a nectarine.
No, Jonagold is a triploid variety. It cannot be used as a pollinator (and it requires a pollinator).
No, apple trees do not need a companion tree. An apple tree will flourish all by itself. Most varieties of apple require a pollinator in the vicinity. Only a small number are self fertile.
yes
Mulberry trees need two trees to produce a fruit, as this tree has separate female and male trees. The male tree can literally be miles away and its pollen can still easily reach the female tree on wind currents. Some types of cherry trees are self-pollinating and don't need a second tree to produce fruit. The nectarine is it's own fruit however it is a classical example of bud variation. The nectarine tree occasionally produces peaches, and the peach tree occasionally produces nectarines.
This type of tree is a self pollinator so it needs a partner tree close by. Several other types of apples will do, but one website says that white blossom crab apples will do.
Yes, plums need the correct pollinator. The right one depends on which variety you have.
Bruce Plum tree is not a self pollinator, but this is no big deal as bees and insects will do the pollination process.
no newt is not a pollinator
Cherry TreeApple or Pear TreePeach or Nectarine TreePlum TreeApricot Tree