Cedar Apple Rust

Look what the rains brought out! These orange alien fruiting bodies belong to Gymnosporangium juniperi-virginiana, the fungus that causes cedar apple rust. I finally found one so that I can share a picture that I took! We have had a lot of rain in the past week, and I saw this one along my route to work. This rust has two hosts, the juniper on which these gall are formed and rosaceous hosts primarily apple. The fantastic spore tendrils come out in the spring in response to rains. The teliospores on these structures produce basidiospores which go to the newly expanding leaves of apple and crabapple. Fungicdes can help to protect the apple. Pruning out the galls on juniper will help to break the cycle of spores. Gall will last several years on juniper and get larger each year. This one was at least three inches across, when sporulating!

NFG 5/13/2018