In order to ascertain how far apart fruit pollinators can be planted, it's important to first understand what constitutes pollination, and how that process is accomplished. Pollination is the transfer of pollen from the stamen, the male part of a fruit tree, to the pistil, the female part of a tree. This transfer is accomplished by a great variety of different means, not just honeybees. Other agents of stamen-to-pistil transfer include the wind, rain, butterflies, moths, and birds.
There's also the issue of whether a fruit tree is self-pollinating or cross-pollinating. In the former case, the pollination process can be accomplished within the same single tree, from the same type of pollen. As such, these trees are not as dependent on being near another tree. In the latter case, cross-pollinating trees require fertilization from a separate type of so-called "cultivar." For these kinds of trees, the space separating one from another becomes much more critical.
Maximum, Minimum Distances
Generally speaking, fruit pollinators should not be farther than 200 feet apart. In many cases, planting occurs closer to a 100-foot gap spacing.
But it's not just maximum distance that is an issue when planting fruit pollinators. There is also the matter of a minimum planting distance. For apple trees, it can range for standard specimens from eight feet to thirty feet; for pear trees, 12 to 25 feet; cherries, 18 to 25 feet; and peach and plum trees, 20 feet.
Another issue that novices may not consider is something called "wind drainage." Just like water drainage, cold wind - one of the key agents of pollination - flows in a certain direction: downhill. Although it is often not possible to avoid flat land planting, a downslope is more ideal, as buds from these trees can flow downwards toward the next tree more easily.
The art of properly cultivating a fruit orchard is complicated. Among the other factors that can influence the success of properly spaced tree pollination are: depth of seedling planting; quality of the soil; limb spreading; pruning; and anchoring mechanisms.