Hi it is the 4th season I have the same problem (please see the attached picture). in early April I sprayed it with "Dormant Spray Kit" (horticulture oil & lime sulphur), 1 weeks ago, after blooming was gone I sprayed it with Lime Sulphur again, but the result still the same. I do it for 2 seasons, but ...
The yellow spots are a sure sign of Pear Trellis Rust, a fungal disease that has no treatment except destruction of the junipers that are the alternate host for the fungus. If the junipers are located on someone else's property, you are out of luck. At least in BC there are no fungicides registered for treatment of this disease. You can check if that's also the case in Ontario.
yap, 2 years ago all the pear trees in area were full of this thing. The last year was kind of better and I hoped that this year will be completely different - looks like not. Thanks for the info, at least I know why my treatment doesn't work.
