There are several rusts that can hit pear:
Depending on the species we might come up with a different plan focused on eliminating the alternate host. Did you recently plant a new conifer?
Not sure that my previous answer went through. Small orchard at 1200 feet elevation in area of Doug fir, Grand fir, some Western red cedar forest. Also broad leaf maple, vine maple, etc. We planted 3 Incense cedar about 100 feet from pears, but that was done more than 12 years ago. We recently (1 month ago) planted about 400 Western red cedar seedlings (in a logged area) some 1000 or more feet from the orchard. Other than these, no plantings of conifers.
Have a look at the incense cedars for the rust. It may be dried up right now but there may be some active "orange jelly" in this rain. It is the most likely explanation.
We found no sign of rust on any of our conifers. Nothing on the Incense Cedar. I am attaching photos of what we're calling "pear rust" from the Bennett pear. At this point, that is our most affected tree. I appreciate whatever help you can offer.
This sometimes call pear rust mite or pear blister mite. Very small, 6 legs, has nothing to do with the rust fungi:
Dear Jay, We had some researchers at OHSU look at the infected leafs through a microscope. The report: "We looked under the microscope — no bugs, just lots of red/orange pigment Clear verdict: rust." So it looks like the pear rust mite is not responsible. Do you agree? If so, any recommendations for how we should proceed? Thank you again.
Pigment does not equal rust. I agree you (and they) saw a rust colored pigment. The mites are extremely small and not your average bugs. The feeding is what causes the symptoms you see. This is a very common problem through out the valley. If you had the fungal rust then you (or they) would see the fungal spores in the rust pustual area. The spores are rust colored which is where the name comes from. These spores would be obvious under the microscope.
We looked again and found evidence of a few mites. (it's now been a few days since we removed a few leafs from the most affected tree.) So thank you, you were (of course) correct. As far as I understand, there is nothing we can do until the fall. (Small fruit spurs have now emerged.) Let me know if that is incorrect and a spray of one form or other would be helpful. Again, thank you for your assistance.
Try this publication: