David Owens, Extension Entomologist, owensd@udel.edu
Congratulations to Mark Wainwright, among many others, for correctly identifying this pest as Cedar Apple Rust! Mark and those who submitted correct id’s will be entered in an of season raffle for a scouting toolkit and a jar of local honey.
This from graduate plant pathology student Madeline Henrickson:
Cedar apple rust is caused by the fungal pathogen Gymnosporangium juniperi-virginianae. This pest infects both apple and juniper trees to complete its life cycle. Round galls form on juniper trees, and spore horns elongate, creating an orange gelatinous mass (pictured). Spores from these galls move to infect apple trees, creating the telltale orangish red leaf spots resembling rust. Rust lesions can form on apple leaves or fruits themselves.
Guess the pest image