It depends on the type of apple tree, some are self pollinating and some need other trees pollen in order to pollinate.
Bruce Plum tree is not a self pollinator, but this is no big deal as bees and insects will do the pollination process.
The fruit tree is either a self- pollinating variety or it requires a different variety nearby to allow cross - pollination. This is not affected by the application of fertiliser, although the tree will benefit growth wise.
hand pollination will increase yield. By definition, however, grapefruit trees are self-pollinating.
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.
Some figs are self-pollinating, but Smyrna and some others need pollinating with the caprifig. Wind, bees and other insects cannot access the pollen of the caprifig, and so the fig wasp must do it.
On some plants, yes their flowers contain both stamens and pistils and can be self pollinating. However this is not true of all plants.
They are protected by the fruit of the apple tree, the apple its self
Cut it down. Some species are not self-pollinating, but the "English" walnut is, so there's no reasonable way to keep it from producing fruits.
because it is an apple tree
The apple blossom grows on an apple tree. The apple tree grows when you plant an apple seed.
anywhere from 2-100 years, depends on the variety