Rust disease caused by Uredinopsis osmundae on balsam fir, Canaan fir, white fir, and sensitive fern reported from Pennsylvania, USA

Pennsylvania is the fourth largest Christmas-tree-producing state in the USA, with annual sales of more than $22 million. During the summers of 2018 and 2019, a rust disease was observed on the leaves of balsam fir, Canaan fir, white fir, and sensitive fern in a Christmas tree crop in PA, USA. The specimens were sent to the Arthur Fungarium at Purdue University for further identification and long-term deposit. Based on morphological characteristics and sequence analysis, the rust species was identified as Uredinopsis osmundae. To our knowledge, this is the first report of Uredinopsis osmundae on balsam fir, Canaan fir, white fir, and sensitive fern in PA.