Your trees likely suffer from pear scab. To control pear scab remove the infected leaves and fruit from under the tree in the fall after the leaves have been shed. Either compost the leaves and fruit a good distance from the tree or dispose of them. Lime and fertilize underneath the tree to speed decomposition of any leaves left over. In the spring if you have had a severe infection, it's good to spray the tree starting at the time the buds begin to break, then again a month after petal fall with a fungicide, like sulfur, Bordeaux mixture, neem oil or copper.
Here are a couple of publications may find useful.

https://extension.oregonstate.edu/news/april-showers-could-bring-fungus-fruit-trees
https://pnwhandbooks.org/plantdisease/host-disease/pear-pyrus-spp-scab

Hope this helps!