Hello,

I’m sorry to hear about your crabapple tree. Apple and crabapples are susceptible to several diseases such as fire blight, scab, canker, and rust to name a few. Read more here: https://extension.psu.edu/crabapple-diseases And here: https://portal.ct.gov/CAES/Fact-Sheets/Plant-Pathology/Common-Diseases-of-Crabapple

The trees are also prone to attack by insects such as mites, aphids and Japanese beetles. https://hgic.clemson.edu/factsheet/apple-crabapple-insects/

It would appear that your tree suffers from cedar-apple rust. This is a fungal disease and in order to control it, rake up and dispose of affected leaves to remove fungal spores (the spores can splash up on the tree when during rainstorms. Read more here: https://extension.umn.edu/plant-diseases/cedar-apple-rust

Of course, it is difficult to diagnose a problem from pictures. For a more definitive diagnosis and instructions on treatment, submit a sample to MSU Extension’s Plant and Pest Diagnostics Lab at https://www.canr.msu.edu/pestid/

You can also contact a certified arborist for an assessment of the tree. To find an arborist in your area, go to www.treesaregood.org, the website of the International Society of Arboriculture.

Thank you for contacting Ask Extension.