I have been looking for information on maximum spacing for cross pollination in fruit trees, of specific concern are pear, peach and plum trees in planting on a large home lot with many established trees. Unfortunately most of the information I find is based upon optimal spacing for orchards. Optimal and maximum may be two very different things. The lot in question is about 7 acres and is a tapered wedge shape, about 900 feet long by about 200 feet wide at the narrow end and maybe 400 feet wide at the long end. Over the last couple of years I have been in the process of adding new fruit trees, and replacing old no longer productive peach and plum trees. In the process some things are being moved around, and some trees are being planted a good distance apart at sites where there there is good soil and lighting conditions where there are not in excessive shade from large trees, etc. Resulting in things like the primary area where the new peach and plum trees are being located is about 300 feet from the old cluster, and pear trees being spread over the entire property here and there where there is space for them with good soil and available sunlight.
Unfortunately due to these restrictions and others I have ended up with situations where some of the pear trees are 200-300 feet away from the nearest pear tree of a different variety, and I am wondering if this will be close enough for effective if not optimal pollination? In time all the peaches and plums will be in the same general area, my goal being to add 1-2 varieties every couple of years so that in 20-30 years they don’t all age out at the same time again, but for now I have to deal with 300+ ft separation, though by next spring I hope to have cross pollination options in the new cluster area. .