Hello,

Leaf spot is a fungal disease of ornamental pears caused by a variety of different fungi. The disease appears in the form of scattered but definite, oval to round spots on the leaves. Leaf spot is most evident during summer and persists during periods of light and frequent rainfall, humidity, and fog. Leaf spot leads to premature defoliation in trees, gradually weakening the tree and stunting growth. The presence of leaf spot increases tree susceptibility to a number of other diseases such as bark borers and winter injury. Preventive measures include the application of ammonium nitrate fertilizer and pruning trees to improve air circulation.

I am providing information on leaf spot diseases of ornamental pears - MY RECOMMENDATIONS AND CONCLUSIONS are at the end

Ornamental pear can get a number of leaf spot diseases, apple scab being one of them. Cleaning up fallen leaves and angling sprinklers so they do not wet the leaves of the trees are two important things you can do to minimize the problem.

Apple Scab: https://www.canr.msu.edu/ipm/uploads/files/WoodyLandscape_PDFs/AppleScab.pdf

http://ipm.ucanr.edu/PMG/PESTNOTES/pn7413.html

Other leaf spot diseases of pear are Fabraea, Pear Scab, Pear Rust Mite, Entomosporium leaf spot, Anthracnose, and European Pear Rust/Pear Trellis Rust

Fabraea: https://www.canr.msu.edu/ipm/diseases/fabraea_leaf_spot

Pear Scab: https://www.canr.msu.edu/ipm/diseases/pear_scab

Pear Rust Mite: https://www.canr.msu.edu/ipm/diseases/pear_rust_mite

Entomosporium leaf spot: http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/entomoslfspt.html

Anthracnose: https://www.canr.msu.edu/resources/anthracnose-1

European Pear Rust/Pear Trellis Rust: http://www.ladybug.uconn.edu/FactSheets/pear-trellis-rust_18_<personal data hidden>.pdf

https://www.canr.msu.edu/news/scout_your_bradford_pears_now_for_european_pear_rust

RECOMMENDATIONS AND CONCLUSIONS

The pear appears to have a fungal disease called 'Trellis Rust' also known as European Pear Rust. This disease requires two host plants to complete its life cycle. (See the section labeled 'Separation anxiety' in the attached publication.) The following fact sheet gives management options.

http://www.gpwmi.us/Docs/Departments/DPW/Environmental/pear%20tree%20trellis%20rust.pdf

You may want to send a leaf sample to the MSU Diagnostic lab to positively identify this problem. Details and instructions are at this link:

www.pestid.msu.edu

If your tree is large you will need a professional who has tools with enough power to reach the top of the tree. You can find certified arborists here. You can search by zipcode---

https://www.treesaregood.org/findanarborist/arboristsearch

Hope this helps!!

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