Orange Tubes on Pear Fruit

Q: These pears are on a 30 year old hard pear tree. Approximately 80% of the fruit look this way. When the fruit were the size of a marble, they were deformed. After several weeks, they developed bright red bristles which shed spores which sometimes showed up on leaves below.

A: It’s either cedar-quince rust, Gymnosporangium clavipes, or cedar-hawthorn rust, Gymnosporangium globosum. Either one can have the orange/pink aecia (tubes) on fruit as well as on leaves and twigs.

Yellow spots on the leaves is a more typical symptom.

I’ve never seen aecia on apple fruit infected with the similar cedar-apple rust, Gymnosporangium juniperivirginianae.

Cedar-quince rust

Cedar-hawthorn rust

Cedar-apple rust

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