Pear Rust - Ask Extension
Hello! My Bosch and Bartlet pear trees have started experiencing what looks to be rust. Online sources say to treat with a fungicide and prune, howeve...
Knowledgebase
Pear Rust #873013
Asked June 13, 2024, 4:42 PM EDT
Hello! My Bosch and Bartlet pear trees have started experiencing what looks to be rust. Online sources say to treat with a fungicide and prune, however I’m wondering if you could identify or advise differently. Thank you :)
Yamhill County Oregon
Expert Response
Hi Daniel,
Some years are worse than others for facilitating the growth of fungal diseases. From the photo is looks like it might indeed be Pacific Coast pear rust in early stages. However, when needing positive identification of a disease, a physical specimen is best. If you are able, take a sample into the Yamhill County OSU Extension office. Then the Master Gardeners on site will be able to look at the leaf spots under a microscope to look for fungal fruiting bodies. They will positively identify the disease and give you clear directions for what you can do.
Here's a link to HortSense from University of Washington Extension on Pacific Coast Pear Rust. Apparently there is an alternate host which makes it a challenge to eliminate the rust. It doesn't look like there is a fungicide available to the home gardener for the prevention of rust. As with any fungal disease, keeping dropped fruit and leaves cleared away is essential.
Here's a link to the Pacific Northwest Plant Disease Handbook from OSU Extension for Pacific Coast Pear Rust. You will notice that none of the registered fungicides for edible pears are available to the homeowner. This page does list the alternate host of the disease and some cultural practices to reduce the impact of the rust. Fortunately you have a Bartlett and they are not affected as much as other species of pears.
Some years are worse than others for facilitating the growth of fungal diseases. From the photo is looks like it might indeed be Pacific Coast pear rust in early stages. However, when needing positive identification of a disease, a physical specimen is best. If you are able, take a sample into the Yamhill County OSU Extension office. Then the Master Gardeners on site will be able to look at the leaf spots under a microscope to look for fungal fruiting bodies. They will positively identify the disease and give you clear directions for what you can do.
Here's a link to HortSense from University of Washington Extension on Pacific Coast Pear Rust. Apparently there is an alternate host which makes it a challenge to eliminate the rust. It doesn't look like there is a fungicide available to the home gardener for the prevention of rust. As with any fungal disease, keeping dropped fruit and leaves cleared away is essential.
Here's a link to the Pacific Northwest Plant Disease Handbook from OSU Extension for Pacific Coast Pear Rust. You will notice that none of the registered fungicides for edible pears are available to the homeowner. This page does list the alternate host of the disease and some cultural practices to reduce the impact of the rust. Fortunately you have a Bartlett and they are not affected as much as other species of pears.
