Gymnosporangium yamadae occurs in Northeastern USA
As reported in EPPO RS 2009/129, the occurrence of Gymnosporangium yamadae (EPPO A1 List - Japanese apple rust) in the USA was confirmed in 2009. This was the first record of this rust in North America. In Asia, the aecial stage of G. yamadae is found on Malus species and the telial stage on Juniperus chinensis. In the USA, the aecial stage of this rust was first observed in Wilmington (Delaware) and nearby in Media (Pennsylvania) on leaves of Malus toringo, an ornamental plant native to Asia. In April 2009, telial galls of G. yamadae were found on ornamental J. chinensis trees near the original finding site. In August 2009, G. yamadae was detected on leaves of apple trees (Malus domestica) growing on the farm of the University of Delaware, in Newark. Following these findings, USDA released a Pest Alert to draw the attention of fruit growers to this new disease. The analysis of more samples submitted to USDA/APHIS-PPQ indicated a widespread incidence of the aecial stage of G. yamadae in Northeast USA. G. yamadae has been detected in Connecticut, Maine, Maryland, New Hampshire, New Jersey, New York, Pennsylvania, and Rhode Island. It is thought that G. yamadae has remained undetected for several years because of its similar symptomatology with G. juniperi-virginianae (EPPO A1 List – cedar apple rust) which occurs in North America.
The situation of Gymnosporangium yamadae in the USA can be described as follows: Present, first observed in 2004 and 2008 on ornamental Malus toringo, then on apple trees (Malus domestica), now widespread in Northeastern USA (Connecticut, Delaware, Maine, Maryland, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island).
Sources
Gregory NF, BischoffJF, Dixon LJ, Ciurlino R (2010) First report of the telial stage of Japanese apple rust on Juniperus chinensis in North America and the aecial stage on Malus domestica. Plant Disease 94(9), p 1169.
INTERNET (last retrieved in 2010-11)
The Connecticut Agricultural Experiment Station. Gymnosporangium rusts: common cedar rust diseases in Connecticut by SM Douglas (dated October 2010) http://www.ct.gov/caes/lib/caes/documents/publications/fact_sheets/plant_pathology_and_ecology/gymnosporangium_rusts_10-19-10.pdf