I planted a cordon pear early this year, and it has developed what I take to be pear rust - orange spots on top of some leaves and peculiar orange-brown growths on the underside. It doesn't appear to be a bad infection and the tree is vigorous enough. Should I ignore it? Remove affected leaves? I gather this is a fungus that spends half its life cycle on pears and half on junipers. My assumption is that the tree was already infected when it came from the nursery but I could be wrong - I don't know at what time of year pear trees get infected.

Have a look at this - pear rust survey


http://www.sylva.org.uk/treewatch/surveys.php?survey=2