Quince rust is a fungal disease that attacks fruit of mayhaw, apple, quince, and pear. Infected mayhaw fruit will have a spiny appearance with a coating of orange, powdery fungal spores. Mayhaw are susceptible to infection during the bloom through petal-fall period.
A unique aspect of this disease is that the Eastern red cedar and some junipers are needed for completion of the disease life cycle. The pathogen completes part of its life cycle on cedars or junipers and part on mayhaws. The disease affects the fruit on mayhaws while the disease manifests itself as cankers on the twigs, limbs, or trunk of cedars and junipers.
There are no mayhaw varieties resistant to quince rust. Removing cedars and junipers growing close to the mayhaw plantings could reduce the fungal spores that could result in disease. However, this isn’t always practical. A fungicide application from the time flower buds begin showing color through bloom would help manage the disease.
Featured image by John Hartman, University of Kentucky, Bugwood.org