Cherry fruit die off
We have a cherry try that is several years old and so far we have only had a couple of good years for fruit. This year I tried to be proactive at doing copper spray and horticultural oil in winter, following the directions on the bottle. So far the foliage looks good and we seemed to get a lot of fruit, but in the last week or two the fruit has started to either shrivel up or get red and blotchy. Some of the fruit has spots on it. Now there seems to be less that half the fruit left that looks like it will survive. Any idea what is wrong?
Some of the shriveled fruit is due to a normal process that all cherry trees go through of aborting fruit that it cannot support, or was not fully pollinated. This process is called "June drop". An example is the lower two fruit shown in picture 3. The fruit that is blighted in picture 1 and that is blighted in picture 2, as well as the flowers that are blighted in picture 2, are infected with a disease called brown rot. The article located at this web site (https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-brown-rot-blossom-blight-fruit-rot) gives a good description of the disease with suggested control measures.