Knowledgebase
Rust control for pear trees #858459
Asked February 04, 2024, 12:50 PM EST
Hello,
I planted 2 bare root pear trees (1 moon glow and one dwarf seckle) in my yard about 4 years ago. They are the only trees I have on my property, but we have been struggling with rust every summer. They have begun blooming and fruiting the last two years. They have a very small yield. But I don't know if that is because of disease or simply because they are so young. I do have some copper spray, but I don't know if that is the best course of treatment, and if so, when and how much I should apply, or if the rust or the copper treatment will affect the safety of the fruit if we hope to consume it. I do not have photos as there are currentlly no leaves on the trees. Any advice would be appreciated.
Macomb County Michigan
Expert Response
Without images, it is extremely difficult to give a proper diagnosis. To determine if the problem is, in fact, pear rust.
Here is some information on the management and treatment of pear rust:
Control of rust disease on pear trees has a critical period of time in early spring. Thorough coverage of a fungicide spray repeated 2 to 3 times during the wet period of spring is important. Thorough coverage of the tree is also important.
There needs to be a host for the pear rust to occur.
You should also scout your area for junipers that show the second part of the lifecycle of rust disease. (These junipers might be on another person's property) This second host of rust disease shows Juniper galls that can be pruned out, reducing the rust spores in the area. You can also treat junipers now with a fungicide to reduce fungal infection on that plant or remove the junipers completely from the area. See the details in the links below.
Here is the paragraph describing fungicide treatment from the reference below:
“Fungicides have the potential to inhibit or minimize infections. Timing is critical. For example, spores are released from juniper for infection of pear from two to three weeks in late April to early to mid-June, at least according to observations over the past couple of years. Fungicides should ideally be applied before spore release and infection. The application of fungicides after the infection has taken place will be useless. Fungicides can also be applied to junipers to protect them from infection in the fall, typically late September to early October. Fungicides can be applied by cover sprays or by trunk injections… Thiophanate-Methyl and Chlorothalonil, and Propiconazole and Chlorothalonil.”
Here is a reference from Oklahoma State University that describes the details of treating pear trees for rust diseases. At this link:
https://extension.okstate.edu/fact-sheets/print-publications/epp-entomology-and-plant-pathologhy/pear-rust-epp-7681.pdf
Here is another pear rust reference from Kansas State:
https://hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/Pear%20Rust.pdf
I hope this helps. Please let me know if you have any other questions.
Hello again,
Based on your images this may not be pear rust.
For a confirm and precise identification of the problem, I recommend you send all your images by e-mail to the MSU Plant & Pest Diagnostics Lab. The experts there can also provide you with the best treatment options. Their email is <personal data hidden> - Please include your name – The lab will let you know if they need a sample sent. FYI – The lab may also ask for additional images too.
Their website is at this link:
Plant & Pest Diagnostics (msu.edu)
Their Contact Information is at this link:
Contact Us - Plant & Pest Diagnostics (msu.edu)
This link will explain the details on submitting a sample to MSU Plant & Pest Diagnostics Lab:
Submit Samples - Plant & Pest Diagnostics (msu.edu)
I hope this helps!
