That is peach leaf curl, a common disease of peaches, nectarines, and sometimes apricots. Peaches, nectarines and apricots are difficult to grow in western Oregon due to our cold rainy spring weather, which coincides with bloom time, as well as their susceptibility to various diseases.

The disease did not come in with the pear tree, which is not a host plant for peach leaf curl, it was probably infected by spores travelling by wind or splashing water, or it came in with the tree from the nursery. Peach leaf curl, if severe enough, can cause complete defoliation of a tree. Defoliation from severe infections will weaken the tree to the point that, if not controlled, it may die in 2 to 3 years.

Two fungicide applications are required to manage peach leaf curl, one at about 50% leaf fall (late October-early November,) and the second just before bud swell (usually in late February, before the floral buds open). For home gardeners, your best options are chlorothalonil or copper based fungicides, and chlorothalonil is the more effective fungicide of the two (for home gardeners, trade names with chlorothalonil include Bonide Fung-onil, GardenTech Draconil, and Ortho MAX Garden Disease Control). For more on leaf curl, refer to: https://solvepestproblems.oregonstate.edu/plant-problems/peach-leaf-curl.

In addition to leaf curl, I see blighted flowers in the photos, which may be a symptom of Brown Rot Blossom Blight, another common disease of peaches, nectarines, and apricots. To manage brown rot, prune out and and destroy infected twigs in summer, and at the end of the harvest season, remove and destroy any mummified fruit in or around the tree. In the winter, prune the tree to open it up and improve air circulation in the canopy, which will reduce the moist humid conditions that favor the disease. Fungicides, such as chlorothalonil, can be applied just before blossoms open, and again at full bloom. For more information on Brown Rot, including photos of the symptoms, refer to: https://pnwhandbooks.org/plantdisease/host-disease/peach-prunus-persica-brown-rot

You can find more information on Managing Diseases and Insects in Home Orchards in OSU Extension publication ec631 https://catalog.extension.oregonstate.edu/ec631.