Japanese Beetles just LOVE cherry tree leaves and roses. I spray Sevin daily on my morning and afternoon walk around my garden. I also put up a trap. Together with Sevin and my trap, I do what I can to protect the foliage as best that I can. However, I did apply milky spores earlier this spring so I am hoping that this will soon kick in. It will take about a year to notice in the garden, but I think I am already noticing a slow decline in the amount of beetles buzzing out of my lawn. Last year, they would swarm out of my front lawn in numbers too many to count.

Not too close at all. And you're not going to have to worry about pruning for years.

In my yard in east Tennessee I found that the Japanese beetles feast upon my Montmorency and Lutowka Rose sour cherry (from Poland) trees, but the newer hybrid Carmine Jewel and Romance series sour cherry trees developed by the University of Saskatchewan, including Carmine Jewel, Romeo, and Juliet get pretty much left alone. But maybe that's because the beetles become full from eating the leaves from the straight Prunus cerasus trees. But it could be that the Romance series trees inherited some resistance genes from the Prunus fruiticosa (Mongolian cherry) parent.

slice - I always wondered about all the paintbrush pollination too (with respect to citrus). Some types of fruiting trees (and shrubs, perennials, etc) need pollination from a different flower to actually set fruit. But for citrus, most of which (save some like mandarins) are self-fertile, you don't need to really do anything. Within the flower, the pollen on the anthers will easily make contact with that same flower's stigma. Cross-pollination from other trees would generally help to make seeds (assuming the pollen is not sterile). In some cases, the tree exhibits "parthenocarpy", meaning they produce fruit with little or no seeds. Manual pollination would theoretically ensure the process but more often than not, you might end up damaging the stigma depending on how you jam a brush in the flower. If your tree is outside, the breeze and/or insects will help that process. Inside, you could always put a fan on it if you feel you need to do something. ALso "FP" = Foliage Pro in reference to a fertilizer product made by Dynagro - https://dyna-gro.com/foliage-pro