I’m picky about keeping fruit clean. I use Infuse and Bonide’s Fruit Tree and Plant Guard. Both contain effective brown rot fungicides that work using different modes of action. Like you attack the rot on two fronts, not just one method.
This for me has completely eliminated brown rot on any of my fruit including peaches, plums and sweet cherries. Last year I only made 3 sprays. I have used as many as 5 sprays, the last being July 15th. I alternate products using both at least once every year. I like using Plant Guard first as it also has an insecticide I need for PC. I add a different insecticide to Infuse when I spray. PC is a problem here, but if you spray it’s not really a problem.
The brown rot related blossom blight could be killing your branches, these products will help. Captan would help with that too, but not rotting of fruit. You need at least one.
Anyway if you buy Infuse and a pump sprayer it should be about 35 bucks depending on size of each One gallon size sprayer is fine. I would use a pump sprayer and not a bottle sprayer as you have 8 bush cherries, you need a pump sprayer!
For Japanese beetles I tried Milky Spore bacteria and I didn’t really see much of a change. But it can work in certain areas. I also tried a strain of BT bacteria and that seemed to work. After two years I went from hundreds of Japanese beetles to 7 of them. The BT is a chitin eating bacteria. Chitin is the main component in exoskeletons. Someone then told me to maintain a population of chitin eating bacteria is to feed them! So I bought a bag of pulverized lobster and crab shells, which are loaded with chitin and spread it all over the yard. I do not have a problem, at least for the last 2 years. I hardly see any. If they get bad again I will buy more shells. Chitin eating bacteria not only kill grubs but adult beetles too, one advantage over milky spore which only kills grubs. BT or chitin eating bacteria will kill any beetle too, not just Japanese. So for any beetle problem BT bacteria or lobster.crab shells, both probably best!
Only Gardens Alive sells the BT bacteria and they are not cheap! You can get two forms, one for grubs and one for beetles which you spray the bacteria right on the plants. This is an organic product.
I probably will only use the shells as it attracts the same bacteria, feed them and they will come. No need to pay for the bacteria. This may take longer as only the grubs are killed.
For an acute beetle attack or before you can get the shells to work, the beetle spray might help.
This year I got a 50 pound bag of oyster shells for 15 bucks at a local feed store. Just to add some calcium to my potting mixes. I do not like using lime.