First report of Gymnosporangium yamadae in the USA
In the USA, in August 2004 and July 2008, the aecial stage of a rust fungus was observed in Wilmington (Delaware) and nearby in Media (Pennsylvania) on leaves of Malus toringo, an ornamental plant native to Asia. On the basis of morphological and molecular characteristics, the fungus was identified as Gymnosporangium yamadae (EPPO A1 List). This is the first time that G. yamadae (Japanese apple rust) is reported from the USA, and from North America.
The situation of Gymnosporangium yamadae in the USA can be described as follows: Present, first observed in 2004 and 2008 in Delaware and Pennsylvania respectively, on Malus toringo.
Sources
Yun HY, Minnis AM, Rossman AY (2009) First report of Japanese apple rust caused by Gymnosporangium yamadae on Malus sp. in North America. Plant Disease 93(4), p 430.