Question of the Week – Cedar-Apple Rust

This week, the question was: What is growing on the branch of this cedar tree?

This is a cedar-apple rust gall. These galls have been showing up in cedar trees over the last couple of weeks as the weather has been warm and rainy at times. Cedar-apple rust is caused by a type of fungus that requires two different hosts to complete its life cycle. In this case, the two hosts include cedar and a member of the rose family (frequently apple or crabapple). To read more about cedar-apple rust, take a look at this publication.