Q What is this fungus on my pear tree?
A CHRISTINE SAYS Your tree is showing classic symptoms of pear rust, a fungus that causes orange spots on the top of the leaves from summer into early autumn. As the season progresses, brown swollen areas develop on the lower leaf surface. No chemical treatments are available for the home gardener who wants to eat the fruit. Bayer Fungus Fighter Concentrate and Scotts Fungus Clear Ultra have approval for the control of rust on ornamental plants, so may be used on pear trees grown for ornamental value and where the gardener does not intend to eat the pears. Junipers are an alternate host of the fungus, but as the spores are airborne from a long distance, I do not think removing them is effective at reducing infection.